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Stammeleer L, Xifra P, Serrano SI, Rishniw M, Daminet S, Peterson ME. Blood pressure in hyperthyroid cats before and after radioiodine treatment. J Vet Intern Med 2024; 38:1359-1369. [PMID: 38440934 PMCID: PMC11099771 DOI: 10.1111/jvim.17032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 02/16/2024] [Indexed: 03/06/2024] Open
Abstract
BACKGROUND Hyperthyroid cats commonly have systemic hypertension, with a reported prevalence of 7% to 48%. Although hypertension might be expected to resolve once treatment restores euthyroidism, it can persist or only first develop after treatment. OBJECTIVES To determine the proportion of hyperthyroid cats with hypertension (systolic blood pressure [SBP] ≥160 mm Hg), persistence or first development of hypertension after successful radioiodine treatment, and correlation of post-treatment hypertension with azotemia or hypothyroidism. ANIMALS Four hundred one hyperthyroid nonazotemic cats were included in the study. METHODS Prospective, cross-sectional and before-and-after studies. All hyperthyroid cats had SBP measured by Doppler; 255 had SBP rechecked 6 months after successful radioiodine (131I) treatment. RESULTS Of untreated hyperthyroid cats, 108/401 (27%) were hypertensive. A higher proportion of hypertensive cats were nervous/excited compared with normotensive cats (47% vs 12%; P < .001). Of the initially hypertensive cats, 87/108 cats were reexamined after 131I treatment; 43/87 (49%) cats normalized SBP, whereas 44/87 (51%) remained hypertensive. Of the initially normotensive cats, 16/168 (9.5%) first developed hypertension after successful 131I treatment. 7/60 (12%) of the 131I-treated hypertensive cats were azotemic and 9/60 (15%) were hypothyroid. A higher proportion of cats remaining hypertensive had nervous/excited demeanor than did normotensive cats (50% vs 17%; P < .001). CONCLUSIONS/CLINICAL IMPORTANCE Hypertension, when present, resolves in many hyperthyroid cats after successful treatment. Hyperthyroid cats uncommonly develop new hypertension after treatment. Persistent or newly detected hypertension was unrelated to azotemia or iatrogenic hypothyroidism. More frequently perceived nervousness/anxiety in radioiodine-treated hypertensive cats suggests that many of these cats might have "situational" hypertension, as hyperthyroid-induced hypertension should resolve after treatment.
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Affiliation(s)
- Lisa Stammeleer
- Small Animal Department, Faculty of Veterinary MedicineGhent UniversityMerelbekeBelgium
| | | | | | | | - Sylvie Daminet
- Small Animal Department, Faculty of Veterinary MedicineGhent UniversityMerelbekeBelgium
| | - Mark E. Peterson
- Cornell UniversityIthacaNew YorkUSA
- Animal Endocrine ClinicNew YorkNew YorkUSA
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Peterson ME, Rishniw M. Urine concentrating ability in cats with hyperthyroidism: Influence of radioiodine treatment, masked azotemia, and iatrogenic hypothyroidism. J Vet Intern Med 2023; 37:2039-2051. [PMID: 37668163 PMCID: PMC10658547 DOI: 10.1111/jvim.16849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 08/23/2023] [Indexed: 09/06/2023] Open
Abstract
BACKGROUND Hyperthyroid cats often have urine specific gravity (USG) values <1.035. It remains unclear how USG changes after treatment, if USG can be used to predict azotemia after treatment, or how iatrogenic hypothyroidism influences USG values. OBJECTIVES To determine the proportion of hyperthyroid cats with USG <1.035 vs ≥1.035; if USG changes after treatment; and whether USG <1.035 correlated with unmasking of azotemia or hypothyroidism. ANIMALS Six hundred fifty-five hyperthyroid cats treated with radioiodine; 190 clinically normal cats. METHODS Prospective, before-and-after study. Hyperthyroid cats had serum thyroxine, thyroid-stimulating hormone, and creatinine concentrations, and USG measured before and 6 months after successful treatment with radioiodine. RESULTS Of untreated hyperthyroid cats, USG was ≥1.035 in 346 (52.8%) and <1.035 in 309 (47.2%). After treatment, 279/346 (80.6%) maintained USG ≥1.035, whereas 67/346 (19.4%) became <1.035; 272/309 (88%) maintained USG <1.035, whereas 37/309 (12%) became ≥1.035. Only 22/346 (6.4%) with USG ≥1.035 developed azotemia after treatment, compared with 136/309 (44%) with <1.035 (P < .001). Of cats remaining nonazotemic, 38% had USG <1.035, compared with 20% of normal cats (P < .001). The 137 cats with iatrogenic hypothyroidism had lower USG after treatment than did 508 euthyroid cats (1.024 vs 1.035), but USGs did not change after levothyroxine supplementation. USG <1.035 had high sensitivity (86.1%) but moderate specificity (65.2%) in predicting azotemia after treatment. CONCLUSIONS AND CLINICAL IMPORTANCE Hyperthyroidism appears not to affect USG in cats. However, cats with evidence of sub-optimal concentrating ability before radioiodine treatment (USG < 1.035) are more likely to develop azotemia and unmask previously occult chronic kidney disease. Iatrogenic hypothyroidism itself did not appear to affect USG values.
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Affiliation(s)
- Mark E. Peterson
- Animal Endocrine Clinic, 21 West 100th StreetNew YorkNew YorkUSA
- College of Veterinary MedicineCornell UniversityIthacaNew YorkUSA
| | - Mark Rishniw
- College of Veterinary MedicineCornell UniversityIthacaNew YorkUSA
- Veterinary Information NetworkDavisCaliforniaUSA
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Prieto JM, Carney PC, Smith SM, Miller ML, Rishniw M, Randolph JF, Salerno VJ, Lamb SV, Place NJ, Farace G, Peterson S, Peterson ME. Biological variation of serum thyrotropin and thyroid hormones concentrations determined at 8-week intervals for 1 year in clinically healthy cats. Vet Clin Pathol 2023; 52:493-502. [PMID: 37528445 DOI: 10.1111/vcp.13251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 02/04/2023] [Accepted: 02/23/2023] [Indexed: 08/03/2023]
Abstract
BACKGROUND Cats commonly develop thyroid disease but little is known about the long-term biological variability of serum thyroid hormone and thyrotropin (thyroid-stimulating hormone; TSH) concentrations. OBJECTIVES We aimed to determine the long-term biological variation of thyroid hormones and TSH in clinically healthy cats. METHODS A prospective, observational study was carried out. Serum samples for analysis of total thyroxine (T4, by radioimmunoassay [RIA] and homogenous enzyme immunoassay [EIA]), triiodothyronine (T3 ), free T4 (by dialysis), and TSH were obtained every 8 weeks for 1 year from 15 healthy cats, then frozen until single-batch analysis. Coefficients of variation (CV) within individual cats (CV I ) and among individual cats (CV G ), as well as the variation between duplicates (ie, analytical variation [CV A ]) were determined with restricted maximum likelihood estimation. The indices of individuality (IoI) and reference change values (RCVs) for each hormone were calculated. RESULTS Some thyroid hormones showed similar (total T4 by EIA) or greater (TSH) interindividual relative to intraindividual variation resulting in intermediate to high IoI, consistent with previous studies evaluating the biological variation of these hormones weekly for 5-6 weeks. By contrast, total T4 (by RIA) and free T4 had a low IoI. Total T3 had a high ratio ofCV A toCV I ; therefore, interindividual variation could not be distinguished from analytical variation. No seasonal variability in the hormones could be demonstrated. CONCLUSIONS Clinicians might improve the diagnosis of feline thyroid disease by establishing baseline concentrations for analytes with intermediate-high IoI (total T4, TSH) for individual cats and applying RCVs to subsequent measurements.
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Affiliation(s)
- Jennifer M Prieto
- Departments of Clinical Sciences, Cornell University, Ithaca, New York, USA
| | - Patrick C Carney
- Departments of Clinical Sciences, Cornell University, Ithaca, New York, USA
| | - Stephanie M Smith
- Departments of Clinical Sciences, Cornell University, Ithaca, New York, USA
| | - Meredith L Miller
- Departments of Clinical Sciences, Cornell University, Ithaca, New York, USA
| | - Mark Rishniw
- Departments of Clinical Sciences, Cornell University, Ithaca, New York, USA
| | - John F Randolph
- Departments of Clinical Sciences, Cornell University, Ithaca, New York, USA
| | - Valerie J Salerno
- Population Medicine & Diagnostic Sciences, Cornell University, Ithaca, New York, USA
| | - Steve V Lamb
- Population Medicine & Diagnostic Sciences, Cornell University, Ithaca, New York, USA
| | - Ned J Place
- Population Medicine & Diagnostic Sciences, Cornell University, Ithaca, New York, USA
| | | | | | - Mark E Peterson
- Departments of Clinical Sciences, Cornell University, Ithaca, New York, USA
- Animal Endocrine Clinic, New York, New York, USA
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De Voogt C, Williams L, Stammeleer L, Peremans K, Vandermeulen E, Paepe D, Daminet S. Radioiodine treatment in hyperthyroid cats: insights into the characteristics of owners and their cats, and owner motivation and perceptions. J Feline Med Surg 2023; 25:1098612X221150191. [PMID: 36744573 PMCID: PMC10812082 DOI: 10.1177/1098612x221150191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES Radioiodine (131I) therapy is the most appropriate treatment option for many hyperthyroid cats, as it is minimally invasive and often curative. Nevertheless, 131I treatment is not always pursued by owners. Hence, it is important to obtain more insight into owner satisfaction during and after 131I treatment, and their decision-making process. In this study, we describe the characteristics of owners and their hyperthyroid cats referred for 131I therapy, and determine owners' motivation and how they experienced the 131I treatment of their cat. METHODS A survey was sent to owners whose cats underwent 131I therapy (n = 1071) between 2010 and 2017 at Ghent University. The survey contained 35 questions with tick-box or free-text answer options concerning family situation, pet insurance, previous therapy, comorbidities, motivation for 131I therapy and owner perception of this treatment. RESULTS In total, 438 owners completed 94% or more of the questionnaire. Over half of the cats (55%) had received previous medical, dietary or surgical treatment. Motivations for changing the initial therapy to 131I therapy included difficulties in administering medication (31%), insufficient improvement in clinical signs (23%), side effects (16%) and following the referring veterinarian's advice (16%). Almost a fifth of owners (18%) were not informed about the existence of 131I therapy by their veterinarian and found information on 131I treatment online or through friends. Hospitalising their cat was very distressing for 17% of owners. Most owners (92%) were satisfied with the treatment. Reasons for dissatisfaction were insufficient communication, iatrogenic hypothyroidism, persistent hyperthyroidism and comorbidities post-treatment. CONCLUSIONS AND RELEVANCE Our study stresses the importance of communication regarding the possible outcome of 131I treatment, the importance of managing underlying comorbidities before treatment and anticipating the stress of owners during their cat's hospitalisation period. The results of this study could help in improving client communication when advising on 131I treatment.
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Affiliation(s)
| | - Lianie Williams
- Small Animal Department, Ghent University, Merelbeke, Belgium
| | - Lisa Stammeleer
- Small Animal Department, Ghent University, Merelbeke, Belgium
| | - Kathelijne Peremans
- Department of Morphology, Medical Imaging, Orthopaedics, Physiotherapy and Nutrition, Ghent University, Merelbeke, Belgium
| | - Eva Vandermeulen
- Department of Morphology, Medical Imaging, Orthopaedics, Physiotherapy and Nutrition, Ghent University, Merelbeke, Belgium
| | - Dominique Paepe
- Small Animal Department, Ghent University, Merelbeke, Belgium
| | - Sylvie Daminet
- Small Animal Department, Ghent University, Merelbeke, Belgium
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Xifra P, Serrano SI, Peterson ME. Effect of radioiodine treatment on muscle mass in hyperthyroid cats. Vet Med (Auckl) 2022; 36:1931-1941. [PMID: 36200596 DOI: 10.1111/jvim.16560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 09/21/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND Approximately 75% of hyperthyroid cats lose muscle mass as accessed with a muscle condition scoring (MCS) system. After treatment, MCS improves as the cats regain muscle mass. OBJECTIVES To quantify the degree of muscle loss in hyperthyroid cats using ultrasonography and evaluate changes in muscle mass after treatment. ANIMALS Forty-eight clinically normal cats and 120 cats with untreated hyperthyroidism, 75 of which were reevaluated after radioiodine-131 therapy. METHODS Prospective cross-sectional and before-after studies. All cats underwent ultrasonography and measurement of epaxial muscle height (EMH), with subsequent calculation of vertebral and forelimb epaxial muscle scores (VEMS and FLEMS). A subset of hyperthyroid cats underwent repeat muscle imaging 6 months after treatment. RESULTS Untreated hyperthyroid cats had a lower EMH than did clinically normal cats (median [25th-75th percentile], 0.98 [0.88-1.16] cm vs 1.34 [1.23-1.58] cm, P < .001). Seventy-seven (64.2%) untreated cats had subnormal EMH. Similarly, compared to normal cats, hyperthyroid cats had lower VEMS (0.93 [0.84-1.07] vs 1.27 [1.18-1.39], P < .001) and FLEMS (1.24 [1.10-1.35] vs 1.49 [1.39-1.63], P < .001). After treatment, EMH increased (1.03 [0.89-1.03] cm to 1.33 [1.17-1.41] cm, P < .001), with abnormally low EMH normalizing in 36/41 (88%). Both VEMS (0.94 [0.87-1.10] to 1.21 [1.10-1.31], P < .001) and FLEMS (1.31 [1.17-1.40] to 1.47 [1.38-1.66], P < .001) also increased after treatment. CONCLUSIONS AND CLINICAL IMPORTANCE Almost two-thirds of hyperthyroid cats have abnormally low muscle mass when measured quantitatively by ultrasound. Successful treatment restores muscle mass in >85% of cats. EMH provided the best means of quantitating muscle mass in these cats.
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Affiliation(s)
| | | | - Mark E Peterson
- Animal Endocrine Clinic, NYC, New York, New York, USA.,College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
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Chow JLY, White J. Radioactive iodine dose and survival in cats with hyperthyroidism (2015-2020). J Feline Med Surg 2022; 24:1001-1007. [PMID: 34730466 PMCID: PMC10812325 DOI: 10.1177/1098612x211056837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Radioactive iodine (131I) is the preferred treatment for feline hyperthyroidism but neither the optimal 131I dose nor consistent predictors of post-treatment azotaemia have been determined. The aims of the study were to evaluate the relationships between: (1) 131I dose and survival; and (2) pretreatment and post-treatment serum creatinine concentration. METHODS Medical records of hyperthyroid cats treated with 131I at a single referral hospital were reviewed. Information regarding signalment, body weight, pretreatment and post-treatment serum total thyroxine concentration (TT4), serum creatinine concentration, 131I dose and survival were determined. Multivariable Cox proportional hazards analysis was used to identify variables associated with survival. Multivariable linear regression analysis was used to identify variables associated with post-treatment serum creatinine concentration. RESULTS One hundred and ninety-eight (79 male, 119 female) cats were treated for hyperthyroidism with 131I (median dose 138 MBq; interquartile range 92-168). Median survival time was 1153 days (range 16-1871). Post-treatment serum creatinine (P <0.001) and age (P = 0.049) were significantly associated with survival. Every 10 µmol/l increase in post-treatment serum creatinine concentration and every year increase in age was associated with a 1.07-fold (confidence interval [CI] 1.04-1.11) and 1.17-fold (CI 1.00-1.37) increase in the daily hazard of death, respectively. Pretreatment serum creatinine concentration was directly, and post-treatment serum TT4 concentration was inversely, associated with post-treatment serum creatinine concentration. Every 1 μmol/l increase in pretreatment serum creatinine concentration was associated with an increase in post-treatment serum creatinine concentration of 0.7 μmol/l (SE 0.17; P <0.001). Conversely, every 1 nmol/l decrease in post-treatment serum TT4 concentration was associated with a 1.2 μmol/l (SE 0.61; P <0.001) increase in post-treatment serum creatinine concentration. CONCLUSIONS AND RELEVANCE Post-treatment serum TT4 concentration was associated with post-treatment azotaemia, which was associated with survival. Although 131I dose was not directly associated with survival, dosing strategies that minimise post-treatment hypothyroidism and azotaemia could improve patient survival.
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Affiliation(s)
- Joyce LY Chow
- Joyce LY Chow BVSc, MANZCVS, CityU Veterinary Medical Centre, G/F-2/F, Trinity Towers, 339 Lai Chi Kok Road, Sham Shui Po, Kowloon, Hong Kong
| | - Joanna White
- Small Animal Specialist Hospital, Sydney, Australia
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Yu L, Lacorcia L, Johnstone T. Hyperthyroid cats and their kidneys: a literature review. Aust Vet J 2022; 100:415-432. [PMID: 35711100 PMCID: PMC9543258 DOI: 10.1111/avj.13179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 04/28/2022] [Accepted: 05/01/2022] [Indexed: 11/28/2022]
Abstract
Hyperthyroidism and chronic kidney disease (CKD) are common diseases of geriatric cats, and often occur concurrently. Thus, a thorough understanding of the influence of thyroid function on renal function is of significant value for all feline practitioners. Among other effects, hyperthyroidism causes protein catabolism and increases renal blood flow and glomerular filtration rate (GFR). These effects render traditional renal markers insensitive for the detection of CKD in cats with uncontrolled hyperthyroidism. Furthermore, the development of iatrogenic hypothyroidism with over treatment of hyperthyroidism can be detrimental to renal function and may negatively affect long-term survival. This review discusses important diagnostic considerations of feline hyperthyroidism, as well as key treatment modalities, with an emphasis on the use of radioiodine and the importance of post treatment monitoring of thyroid and renal parameters. In Australia, a common curative treatment for cats with benign hyperthyroidism (i.e. thyroid hyperplasia or adenoma) is a fixed dose of orally administered radioiodine, regardless of the serum total thyroxine concentration at the time of diagnosis. This review discusses the long term outcomes of this standard of care in comparison with current, relevant research literature from around the world. Finally, this review explores the use of symmetric dimethylarginine (SDMA) in assessing renal function before and after treatment in hyperthyroid cats. SDMA correlates well with GFR and creatinine in non-hyperthyroid cats, but our understanding of its performance in hyperthyroid cats remains in its infancy.
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Affiliation(s)
- L Yu
- Veterinary Referral HospitalDandenongVictoriaAustralia
| | - L Lacorcia
- Veterinary Referral HospitalDandenongVictoriaAustralia
| | - T Johnstone
- Animal Referral Hospital, Essendon Fields72 Hargrave AvenueEssendon FieldsVictoria3041Australia
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Xifra P, Serrano SI, Peterson ME. Radioiodine treatment of hyperthyroidism in cats: results of 165 cats treated by an individualised dosing algorithm in Spain. J Feline Med Surg 2022; 24:e258-e268. [PMID: 35748791 PMCID: PMC10812264 DOI: 10.1177/1098612x221104743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVES Although radioiodine (131I) is the treatment of choice for feline hyperthyroidism, 131I-dosing protocols commonly induce iatrogenic hypothyroidism and expose azotaemia. A recently reported patient-specific 131I dosing algorithm minimised the risk of 131I-induced hypothyroidism and azotaemia, while maintaining high cure rates. The aim of the study was to report results of 131I treatment in a European population of hyperthyroid cats using this patient-specific dosing algorithm. METHODS This prospective case series (before-and-after study) evaluated 165 hyperthyroid cats referred for 131I treatment. All cats had serum concentrations of thyroxine (T4), triiodothyronine (T3) and thyroid-stimulating hormone (TSH) measured (off methimazole ⩾1 week). Thyroid volume and percentage uptake of 99mTc-pertechnetate (TcTU) were determined using thyroid scintigraphy. An initial 131I dose was calculated by averaging dose scores for T4/T3 concentrations, thyroid volume and TcTU; 70% of that composite dose was then administered. Twenty-four hours later, percentage 131I uptake was measured, and additional 131I administered as needed to deliver an adequate radiation dose to the thyroid tumour(s). Serum concentrations of T4, TSH and creatinine were determined 6-12 months later. RESULTS Median calculated 131I dose was 2.15 mCi (range 1.2-7.5), with only 51 (30.9%) receiving ⩾2.5 mCi. Of 165 cats, 124 (75.2%) became euthyroid, seven (4.2%) became overtly hypothyroid, 27 (16.4%) became subclinically hypothyroid and seven (4.2%) remained hyperthyroid. A higher proportion of overtly (85.7%) and subclinically (26.9%) hypothyroid cats developed azotaemia than euthyroid cats (13.6%; P = 0.0002). Hypothyroid cats were older (P = 0.016) and more likely to have detectable TSH concentrations (P = 0.025) and symmetrical bilateral distribution of 99mTc-pertechnetate uptake (P = 0.0002), whereas persistently hyperthyroid cats had higher severity scores (P = 0.012). CONCLUSIONS AND RELEVANCE Our results confirm that 131I dosing with this new algorithm results in high cure rates, with a lowered prevalence of 131I-induced overt hypothyroidism and azotaemia. Age, serum TSH concentrations, bilateral, symmetrical uptake and severity score help predict outcome.
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Affiliation(s)
| | | | - Mark E Peterson
- Animal Endocrine Clinic, New York, NY, USA
- Cornell University, Ithaca, NY, USA
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Urbanschitz T, Burgener IA, Zeugswetter FK. Utility of a canine TSH assay for diagnosis and monitoring of feline hyperthyroidism. TIERARZTLICHE PRAXIS. AUSGABE K, KLEINTIERE/HEIMTIERE 2022; 50:93-100. [PMID: 35523163 DOI: 10.1055/a-1807-9546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
OBJECTIVE This retrospective study was initiated to evaluate the utility of TSH measurements using a common canine TSH assay to diagnose and monitor feline hyperthyroidism after radioiodine or thyreostatic drug treatment. MATERIAL AND METHODS The electronic database of the University of Veterinary Medicine Vienna was searched for combined TSH and T4 measurements. 217 pairs of TSH and T4 from 136 cats with possible hyperthyroidism were assigned to group A (untreated; n = 24) and B (treated; n = 193). Measurements in group B were then subcategorized according to T4 concentrations (reference range 15-50 nmol/L): group B1 = elevated T4 (n = 46), group B2 = normal T4 (n = 84) and group B3 = decreased T4 (n = 63). Group B2 was further divided into cats with low normal (group B2a; n = 35), medium normal (group B2b; n = 29) and high normal (group B2c; n = 20) T4 concentrations. RESULTS TSH was detectable in 4 (17 %) of the 24 untreated cats (group A) and did not return to normal despite seemingly successful therapy in two. Increased TSH concentrations were observed in 3.6 % of the treated cats in group B2 and 2.9 %, 6.9 %, and 0 % in subgroups B2a, B2b and B2c, respectively. Forty-four percent of the treated cats with a decreased T4 (group B3) had an increased TSH concentration. TSH correlated with treatment length (r = 0.358, p = 0.004) and was significantly higher in cats treated for more than 3 months (p = 0.008). CONCLUSION TSH was detectable in a significant number of untreated hyperthyroid cats and thus this parameter should not be used to definitively rule out feline hyperthyroidism. Furthermore, the very low prevalence of increased TSH concentrations in treated hyperthyroid cats with a normal T4 and cost benefit calculations do not support the routine measurement of TSH in these cats. The fact that TSH correlated with time since treatment start and 56 % of the cats with a decreased T4 had TSH concentrations within the reference limits, suggests delayed recovery of the pituitary thyrotrophs which might explain the low prevalence of subclinical hypothyroidism in the present study. CLINICAL RELEVANCE TSH measurement in cats with suspected or treated hyperthyroidism using a canine assay lacks diagnostic sensitivity and can only complement therapeutic decision-making.
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Affiliation(s)
| | - Iwan A Burgener
- Department for Small Animals and Horses, University of Veterinary Medicine, Division of small animal internal medicine
| | - Florian K Zeugswetter
- Department for Small Animals and Horses, University of Veterinary Medicine, Division of small animal internal medicine
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Matos J, Lutz B, Grandt LM, Meneses F, Schweizer-Gorgas D, Francey T, Campos M. Outcome of radioiodine therapy for feline hyperthyroidism: Fixed dose versus individualized dose based on a clinical scoring system. Open Vet J 2022; 12:231-241. [PMID: 35603071 PMCID: PMC9109836 DOI: 10.5455/ovj.2022.v12.i2.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 03/21/2022] [Indexed: 11/22/2022] Open
Abstract
Background Hyperthyroidism is the most frequent endocrinopathy in older cats. To date, there is no consensus on how to best calculate the dose of radioiodine to administer to hyperthyroid cats. Aim The goals of this study were to compare thyroid function, renal function, and survival time between hyperthyroid cats receiving a fixed dose of radioiodine and those receiving an individualized dose calculated using a clinical scoring system. Methods Medical records of 110 cats treated with radioiodine therapy at the University of Bern between 2010 and 2020 were reviewed. Thyroid function, renal function, and survival of cats treated with a fixed dose of radioiodine (2010-2015; n = 50) were compared to those of cats treated with an individualized dose (2015-2020; n = 60) at different time points after therapy. Results Treatment with a fixed dose of radioiodine (mean = 168 ± 26 MBq) was associated with 69% of euthyroidism, 19% persistent hyperthyroidism, and 12% hypothyroidism, whereas treatment with an individualized dose (mean = 120 ± 30 MBq) led to 54% euthyroidism, 23% hyperthyroidism, and 23% hypothyroidism (p = 0.73). More than 12 months after treatment, the incidence of azotemia was comparable between cats treated with a fixed dose (37%) and those treated with an individualized dose (31%) (p = 0.77). No factors were found to be predictive of treatment failure (hypothyroidism or hyperthyroidism) after therapy. Median survival time after radioiodine therapy was 44 months. In a multivariate analysis, persistent hyperthyroidism was the only variable independently associated with a shorter survival time (HR = 6.24, p = 0.002). Conclusion The method of calculating the dose of radioiodine (fixed vs. individualized) to treat feline hyperthyroidism does not appear to be decisive for posttreatment thyroid function, renal function, or survival.
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Affiliation(s)
- Joana Matos
- Small Animal Internal Medicine Division, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Bern, Switzerland
- These authors contributed equally to this work
| | - Bérénice Lutz
- Small Animal Internal Medicine Division, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Bern, Switzerland
- These authors contributed equally to this work
| | - Lisa-Maria Grandt
- Small Animal Internal Medicine Division, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Bern, Switzerland
| | - Felix Meneses
- Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Bern, Switzerland
| | - Daniela Schweizer-Gorgas
- Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Bern, Switzerland
| | - Thierry Francey
- Small Animal Internal Medicine Division, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Bern, Switzerland
| | - Miguel Campos
- Small Animal Internal Medicine Division, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Bern, Switzerland
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Campbell J, Chapman P, Klag A. The Prevalence, Magnitude, and Reversibility of Elevated Liver Enzyme Activities in Hyperthyroid Cats Presenting for Iodine-131 Treatment. Front Vet Sci 2022; 9:830287. [PMID: 35252423 PMCID: PMC8890775 DOI: 10.3389/fvets.2022.830287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 01/03/2022] [Indexed: 11/13/2022] Open
Abstract
ObjectivesThe primary objective of this study was to report the prevalence and magnitude of elevated liver enzyme activity in feline hyperthyroidism using a large cohort of cats presenting for iodine-131 treatment. The secondary objective was to determine if elevated liver enzyme activity was a reversible process following successful iodine-131 treatment.MethodsCases that presented for a single iodine-131 treatment were retrospectively reviewed. Short-term and long-term follow-up clinicopathologic data was then reviewed for the secondary objective.ResultsTwo hundred seventeen hyperthyroid cats met the inclusion criteria for the primary objective. In total, 123/217 (56.7%) of the cats had at least one liver enzyme elevation on their chemistry panel, with alanine transaminase activity being the most common. All cats who were successfully treated with iodine-131 had liver enzyme activity within the reference range at short-term follow-up and long-term follow-up points.Conclusion and RelevanceOur study demonstrates that elevated liver values are common in cats presenting for iodine-131 treatment. Additionally, our study demonstrates that even when liver values are markedly elevated prior to treatment, the liver enzyme activity will return to normal after successful resolution of hyperthyroidism using iodine-131 treatment. Investigation into hepatobiliary disease and liver function tests for cats with a diagnosis of hyperthyroidism may be unnecessary as the liver values will likely return to normal with successful iodine-131 treatment.
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Peterson ME, Rishniw M. Predicting outcomes in hyperthyroid cats treated with radioiodine. J Vet Intern Med 2021; 36:49-58. [PMID: 34817910 PMCID: PMC8783366 DOI: 10.1111/jvim.16319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 11/05/2021] [Accepted: 11/15/2021] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Radioiodine (131 I) is the treatment of choice for cats with hyperthyroidism. After 131 I, however, euthyroidism is not always achieved, with 5% to 10% of cats remaining persistently hyperthyroid and 20% to 50% developing iatrogenic hypothyroidism. OBJECTIVES To identify pretreatment factors that may help predict persistent hyperthyroidism and iatrogenic hypothyroidism after treatment of cats using a novel 131 I dosing algorithm. ANIMALS One thousand and four hundred hyperthyroid cats treated with 131 I. METHODS Prospective, before-and-after study. Pretreatment predictors (clinical, laboratory, scintigraphic, 131 I dose, 131 I uptake measurements) of treatment failure or iatrogenic hypothyroidism were identified by multivariable logistic regression analysis. RESULTS Cats that developed iatrogenic hypothyroidism were more likely to be older (odds ratio [OR] = 1.10; 95% confidence interval [CI], 1.04-1.17; P = .001), female (OR = 2.04; 95% CI, 1.54-2.70; P < .001), have detectable serum thyroid-stimulating hormone (TSH) concentrations (OR = 4.19; 95% CI, 2.0-8.81; P < .001), have bilateral thyroid nodules (OR = 1.57; 95% CI, 1.19-2.08; P < .001), have homogeneous, bilateral distribution of 99m Tc-pertechnetate uptake (OR = 2.93; 95% CI, 2.05-4.19; P < .001), have milder severity score (OR = 0.62; 95% CI, 0.49-0.79; P < .001), and have higher 131 I uptake (OR = 2.40; 95% CI, 1.75-3.28; P < .001). In contrast, cats remaining persistently hyperthyroid were more likely to be younger (OR = 0.81; 95% CI, 0.72-0.92; P < .001), have higher severity score (OR = 1.87; 95% CI, 1.51-2.31; P < .001), and have lower 131 I uptake (OR = 3.50; 95% CI, 1.8-6.80; P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE Age, sex, serum TSH concentration, bilateral and homogeneous 99m Tc-pertechnetate uptake on scintigraphy, severity score, and percent 131 I uptake are all factors that might help predict outcome of 131 I treatment in hyperthyroid cats. Cats with persistent hyperthyroidism had many predictive factors that directly contrasted those of cats that developed 131 I-induced hypothyroidism.
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Affiliation(s)
- Mark E Peterson
- Animal Endocrine Clinic, New York, New York, USA.,College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Mark Rishniw
- College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.,Veterinary Information Network, Davis, California, USA
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13
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Cosford K, Snead E, Hutcheson M, Sukut S. The effect of per os vs subcutaneous 123 iodine administration on percentage thyroidal radioactive iodine uptake in normal cats. J Vet Intern Med 2021; 35:2646-2651. [PMID: 34514652 PMCID: PMC8692174 DOI: 10.1111/jvim.16261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 08/09/2021] [Accepted: 08/30/2021] [Indexed: 11/29/2022] Open
Abstract
Background Historical and recent literature disagree on whether a higher PO 131I dosage, compared to IV or SC routes, is required for successful resolution of spontaneous hyperthyroidism in cats, necessitating investigation into the effect of PO and injectable radioactive iodine administration on % thyroidal radioactive iodine uptake (RAIU). Hypothesis/Objectives To investigate the effect of PO and SC routes of 123I administration on paired % thyroidal RAIU in euthyroid cats. Specifically, a 1.5‐fold difference (50% relative change) was hypothesized, which in absolute terms can be expressed as a 3.25% increase in the mean %RAIU of 7.04% after PO 123I administration to 10.56% after SC dosing. Animals Seven healthy euthyroid teaching‐research colony cats. Methods A randomized, radiologist‐blinded crossover study comparing %RAIU after PO and SC 123I administration. Results Percentage thyroidal RAIU values (mean ± SD; 95% confidence interval) after PO (4.81% ± 1.63%; 3.30%‐6.23%) and SC (5.26% ± 2.43%; 3.01%‐7.51%) 123I administration were associated with a median within‐pair absolute difference of 0.2% (range: min, 0.1%‐max, 4.9%). Statistical significance was not achieved (P = .45). Six of 7 cats had a within‐pair absolute difference of 0.1% to 0.9% (relative change of 4%‐20%), but a single outlier cat had a within‐pair absolute difference of 4.9% (relative change of 108%). Conclusions and Clinical Importance This study did not detect an effect of 123I administration route on paired % thyroidal RAIU in euthyroid cats. However, a type 2 statistical error due to small sample size is possible.
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Affiliation(s)
- Kevin Cosford
- Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada
| | - Elisabeth Snead
- Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada
| | - Matt Hutcheson
- Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada
| | - Sally Sukut
- Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada
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Peterson ME, Rishniw M. A dosing algorithm for individualized radioiodine treatment of cats with hyperthyroidism. J Vet Intern Med 2021; 35:2140-2151. [PMID: 34351027 PMCID: PMC8478068 DOI: 10.1111/jvim.16228] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/02/2021] [Accepted: 07/13/2021] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Radioiodine (131 I) is the treatment of choice for hyperthyroidism in cats, but current 131 I-dosing protocols can induce iatrogenic hypothyroidism and expose azotemia. OBJECTIVES To develop a cat-specific algorithm to calculate the lowest 131 I dose to resolve hyperthyroidism, while minimizing risk of iatrogenic hypothyroidism and subsequent azotemia. ANIMALS One thousand and four hundred hyperthyroid cats treated with 131 I. METHODS Prospective case series (before-and-after study). All cats had serum concentrations of thyroxine (T4 ), triiodothyronine (T3 ), and thyroid-stimulating hormone (TSH) measured (off methimazole ≥1 week). Using thyroid scintigraphy, each cat's thyroid volume and percent uptake of 99m Tc-pertechnatate (TcTU) were determined. An initial 131 I dose was calculated by averaging dose scores for T4 /T3 concentrations, thyroid volume, and TcTU; 80% of that composite dose was administered. Twenty-four hours later, percent 131 I uptake was measured, and additional 131 I administered, as needed, to deliver an adequate radiation dose to the thyroid tumor(s). Serum concentrations of T4 , TSH, and creatinine were determined 6 to 12 months later. RESULTS The median calculated 131 I dose was 1.9 mCi (range, 1.0-10.6 mCi); 1380 cats required additional 131 I administration on day 2. Of the cats, 1047 (74.8%) became euthyroid, 57 (4.1%) became overtly hypothyroid, 240 (17.1%) became subclinically hypothyroid, and 56 (4%) remained hyperthyroid. More overtly (71.9%) and subclinically (39.6%) hypothyroid cats developed azotemia than euthyroid cats (14.2%; P < .0001). CONCLUSIONS AND CLINICAL IMPORTANCE Our algorithm for calculating individual 131 I doses resulted in cure rates similar to historical treatment rates, despite much lower 131 I doses. This algorithm appears to lower prevalence of both 131 I-induced overt hypothyroidism and azotemia.
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Affiliation(s)
- Mark E Peterson
- Animal Endocrine Clinic, New York, New York, USA.,College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Mark Rishniw
- College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.,Veterinary Information Network, Davis, California, USA
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Busser S, Poirier VJ, Liggins C, Bray S. Received dose variability after administration of I-131 for treatment of hyperthyroidism in cats. J Vet Intern Med 2021; 35:1697-1702. [PMID: 34096090 PMCID: PMC8295666 DOI: 10.1111/jvim.16185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 05/10/2021] [Accepted: 05/18/2021] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Injectable radioactive iodine (I-131) frequently is used to treat hyperthyroidism in cats. In human medicine, residual activity after injection of radionuclides has been reported, and the actual quantity administered is recorded after administration. OBJECTIVE Our aim was to evaluate actual administered dose variability after administration of preprepared I-131 single unit doses for the treatment of hyperthyroidism in cats. ANIMALS Twenty-seven cats with hyperthyroidism treated with I-131 between April 2017 and March 2019. METHODS Retrospective observational study of cats treated with preprepared single unit I-131 doses. For each dose, the measured activity before administration and residual activity were recorded. The measured dose and the actual dose administered were compared to the prescribed dose. RESULTS Measured activity before administration ranged from 88.4% to 103.3% of the prescribed dose. Mean residual activity was 5.2 ± 3.0 MBq (ranging from 1.5% to 15% of the prescribed dose). The actual dose administered (measured activity - residual activity) ranged from 79.1% to 100.2% of the prescribed dose. Seventeen of 28 (60.7%) of the actual administered doses differed between 10% and 20% of the prescribed dose. One administered dose had a >20% difference compared to the prescribed dose (79.10% of the prescribed dose). CONCLUSION AND CLINICAL IMPORTANCE Our study identified variability in the residual and actual administered activity of I-131 as compared to the prescribed dose, which should be taken into consideration when treating cats with (predrawn) I-131.
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Affiliation(s)
- Suzanne Busser
- School of Veterinary Science, Massey University, Palmerston North, New Zealand.,The Royal (Dick) School of Veterinary Studies and the Roslin Institute, The University of Edinburgh, Roslin, United Kingdom
| | - Valerie J Poirier
- School of Veterinary Science, Massey University, Palmerston North, New Zealand.,Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Carolyn Liggins
- School of Veterinary Science, Massey University, Palmerston North, New Zealand
| | - Sharyn Bray
- School of Veterinary Science, Massey University, Palmerston North, New Zealand
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BA-plotteR - A web tool for generating Bland-Altman plots and constructing limits of agreement. Res Vet Sci 2021; 137:281-286. [PMID: 34058399 DOI: 10.1016/j.rvsc.2021.05.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 05/20/2021] [Accepted: 05/22/2021] [Indexed: 11/22/2022]
Abstract
Investigators use Bland-Altman plot (Limits of Agreement plot) to compare two methods measuring the same continuous variable to determine interchangeability or agreement of the methods. The method has evolved to deal with heteroscedastic data and fixed or proportional biases (or both). Although an ordinary Bland-Altman plot can be readily made with various software applications, there is no free, open-source application that is dedicated to producing Bland-Altman plots and constructing limits of agreement for data that do not meet the assumptions of a simple comparison. To fill this gap, we created BA-plotteR, a web-based, open-source, freeware tool created in Shiny/R that is dedicated to creating Bland-Altman plots. We validated the tool using 20 datasets with various data distributions by comparing the output from the tool against manually derived results. The webtool handles data that requires a more complex analysis than is commonly available through commercial statistical programs. Moreover, the automated analysis of the data distribution will guide users and help them to correctly plot and analyse their data. The tool agreed perfectly with manually constructed plots. The Bland-Altman graphing tool provides clinical researchers with a tool that correctly analyzes and graphs studies involved in method comparisons. The tool can be accessed here: https://huygens.science.uva.nl/BA-plotteR.
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Mullowney D, Chang YM, Glanemann B, Syme HM. Treatment failure in hyperthyroid cats after radioiodine (I-131) injection. J Vet Intern Med 2021; 35:1688-1696. [PMID: 33999452 PMCID: PMC8295673 DOI: 10.1111/jvim.16161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 04/29/2021] [Accepted: 05/03/2021] [Indexed: 12/17/2022] Open
Abstract
Background There is limited published information on the outcome for cats where total thyroxine concentration (TT4) remains elevated after treatment with radioactive iodine (RAI). Objective To determine the frequency of, and predictors for, subsequent treatment failure in cats for which TT4 remains elevated at hospital discharge, and to report clinical outcomes for cats requiring repeat treatment. Animals One hundred twenty‐one cats with TT4 ≥40 nmol/L after treatment with RAI (out of an original, treated study sample of 959 cats). Methods Retrospective study. Data regarding signalment, weight, TT4 concentration (before RAI treatment, at discharge, and percentage change), day of sampling, and I‐131 dose were acquired. Logistic regression was performed to evaluate predictors of treatment failure. Results In the 87 cats for which classification was possible, 35 (40%) became euthyroid without further treatment. All TT4 variables and weight normalized RAI dose were independently predictive of subsequent treatment failure. In multivariate analysis, TT4 concentration at discharge (P < .001) and weight normalized RAI dose (P = .04) remained in the final model. All 28 cats with TT4 concentration ≥150 nmol/L at discharge ultimately failed treatment, compared with 13/40 (32.5%) and 11/19 (57.9%) cats with TT4 concentrations of 40‐100 nmol/L and 100‐150 nmol/L, respectively. Of the 52 cats that failed treatment, 14 were subsequently managed medically, 12 underwent thyroidectomy (4 with carcinoma), 14 had repeat RAI treatment which was successful in 12/14 (86%) cats, and 13 had no further treatment. Conclusions and Clinical Importance Cats with TT4 >150 nmol/L at discharge after RAI might be candidates for immediate repeat treatment.
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Affiliation(s)
- Deirdre Mullowney
- Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hertfordshire AL9 7TA, United Kingdom
| | - Yu-Mei Chang
- Research Support Office, The Royal Veterinary College, London, United Kingdom
| | - Barbara Glanemann
- Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hertfordshire AL9 7TA, United Kingdom
| | - Harriet M Syme
- Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hertfordshire AL9 7TA, United Kingdom
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Kongtasai T, Meyer E, Paepe D, Marynissen S, Smets P, Mortier F, Demeyere K, Vandermeulen E, Stock E, Buresova E, Defauw P, Duchateau L, Daminet S. Liver-type fatty acid-binding protein and neutrophil gelatinase-associated lipocalin in cats with chronic kidney disease and hyperthyroidism. J Vet Intern Med 2021; 35:1376-1388. [PMID: 33723886 PMCID: PMC8162613 DOI: 10.1111/jvim.16074] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 01/28/2021] [Accepted: 02/04/2021] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Liver-type fatty acid-binding protein (L-FABP) and neutrophil gelatinase-associated lipocalin (NGAL) are candidate biomarkers for the detection of early chronic kidney disease (CKD) in cats. OBJECTIVE To evaluate urinary and serum L-FABP and NGAL concentrations in CKD cats and in hyperthyroid cats before and after radioiodine (131 I) treatment. ANIMALS Nine CKD cats, 45 healthy cats and hyperthyroid cats at 3 time points including before (T0, n = 49), 1 month (T1, n = 49), and 11 to 29 months after (T2, n = 26) 131 I treatment. METHODS Cross-sectional and longitudinal study. Serum L-FABP (sL-FABP), serum NGAL (sNGAL), urinary L-FABP (uL-FABP), and urinary NGAL (uNGAL) were compared between the 3 groups and between hyperthyroid cats before and after treatment. Data are reported as median (min-max). RESULTS CKD cats had significantly higher sL-FABP (13.50 [3.40-75.60] ng/ml) and uL-FABP/Cr (4.90 [0.97-2139.44] µg/g) than healthy cats (4.25 [1.34-23.25] ng/ml; P = .01 and 0.46 [0.18-9.13] µg/g; P < .001, respectively). Hyperthyroid cats at T0 had significantly higher uL-FABP/Cr (0.94 [0.15-896.00] µg/g) than healthy cats (P < .001), thereafter uL-FABP/Cr significantly decreased at T2 (0.54 [0.10-76.41] µg/g, P = .002). For the detection of CKD, uL-FABP/Cr had 100% (95% confidence interval [CI], 66.4-100.0) sensitivity and 93.2% (95% CI, 81.3-98.6) specificity. There were no significant differences in sNGAL and uNGAL/Cr between the 3 groups. CONCLUSIONS AND CLINICAL IMPORTANCE L-FABP, but not NGAL, is a potential biomarker for the detection of early CKD in cats. Utility of uL-FABP to predict azotemia after treatment in hyperthyroid cats remains unknown.
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Affiliation(s)
| | - Evelyne Meyer
- Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Dominique Paepe
- Small Animal Department, Ghent University, Merelbeke, Belgium
| | | | - Pascale Smets
- Small Animal Department, Ghent University, Merelbeke, Belgium
| | - Femke Mortier
- Small Animal Department, Ghent University, Merelbeke, Belgium
| | - Kristel Demeyere
- Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Eva Vandermeulen
- Department of Medical Imaging of Domestic Animals, Ghent University, Merelbeke, Belgium
| | - Emmelie Stock
- Department of Medical Imaging of Domestic Animals, Ghent University, Merelbeke, Belgium
| | - Eva Buresova
- Davies Veterinary Specialists, Higham Gobion, United Kingdom
| | - Pieter Defauw
- Lumbry Park Veterinary Specialists, Alton, United Kingdom
| | - Luc Duchateau
- Biometrics Research Group, Ghent University, Merelbeke, Belgium
| | - Sylvie Daminet
- Small Animal Department, Ghent University, Merelbeke, Belgium
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Yu L, Lacorcia L, Finch S, Johnstone T. Assessment of treatment outcomes in hyperthyroid cats treated with an orally administered fixed dose of radioiodine. J Feline Med Surg 2020; 22:744-752. [PMID: 31680613 PMCID: PMC10814508 DOI: 10.1177/1098612x19884155] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVES The aims of this study were to describe the treatment outcomes following oral administration of a fixed dose (138 MBq; 3.7 mCi) of radioiodine in hyperthyroid cats and to examine the correlation between total thyroxine (TT4) concentrations before and after treatment. METHODS This was a retrospective cohort study that documented the TT4 concentration and clinicopathological parameters at the time of diagnosis and after treatment. Logistic regression was used to assess the relationship between TT4 concentrations before and after treatment. The difference in pre- and post-treatment variables between cats that had TT4 concentrations below or within the reference interval (RI) was compared by the Mann-Whitney U-test. RESULTS Of 161 cats, 133 (82.6%) cats had TT4 concentrations within the RI, four (2.5%) cats had TT4 concentrations above the RI and 24 (14.9%) cats had TT4 concentrations below the RI after treatment. The severity of hyperthyroidism at diagnosis, as measured by the percentage of TT4 elevation above the upper limit of the RI, had no impact on the odds of cats having low TT4 concentrations after treatment (odds ratio 1.00; 95% confidence interval 0.96-1.05; P = 0.828). CONCLUSIONS AND RELEVANCE When using an orally administered fixed dose of radioiodine for the treatment of feline hyperthyroidism, TT4 concentrations at diagnosis cannot be used to predict TT4 concentrations after treatment. The proportion of cats with TT4 concentrations below the lower limit of the RI after treatment was 14.9%. Further work is required to optimise oral radioiodine dosing to achieve maximal euthyroid outcomes.
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Affiliation(s)
- Lucia Yu
- Translational Research and Small Animal Clinical Trial Study Group, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, VIC, Australia
| | - Lauren Lacorcia
- Translational Research and Small Animal Clinical Trial Study Group, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, VIC, Australia
| | - Sue Finch
- Statistical Consulting Centre, The University of Melbourne, VIC, Australia
| | - Thurid Johnstone
- Translational Research and Small Animal Clinical Trial Study Group, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, VIC, Australia
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Peterson ME. Hyperthyroidism in Cats: Considering the Impact of Treatment Modality on Quality of Life for Cats and Their Owners. Vet Clin North Am Small Anim Pract 2020; 50:1065-1084. [PMID: 32665137 DOI: 10.1016/j.cvsm.2020.06.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In cats, hyperthyroidism can be treated in 4 ways: medical management with methimazole or carbimazole, nutritional management (low-iodine diet), surgical thyroidectomy, and radioactive iodine (131I). Each form of treatment has advantages and disadvantages that should be considered when formulating a treatment plan for the individual hyperthyroid cat. Medical and nutritional managements are considered "reversible" or palliative treatments, whereas surgical thyroidectomy and 131I are "permanent" or curative treatments. The author discusses how each treatment modality could be the optimal choice for a specific cat-owner combination and reviews the advantages and disadvantages of each treatment option.
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21
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Yu L, Lacorcia L, Finch S, Johnstone T. Assessment of serum symmetric dimethylarginine and creatinine concentrations in hyperthyroid cats before and after a fixed dose of orally administered radioiodine. J Vet Intern Med 2020; 34:1423-1431. [PMID: 32506701 PMCID: PMC7379014 DOI: 10.1111/jvim.15831] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/22/2020] [Accepted: 05/22/2020] [Indexed: 12/11/2022] Open
Abstract
Background Serum symmetric dimethylarginine (SDMA) is a sensitive renal biomarker for detecting early chronic kidney disease (CKD) in nonhyperthyroid cats, but knowledge regarding its performance in hyperthyroid cats remains limited. Objectives To determine the relationship between serum SDMA, creatinine and total thyroxine (TT4) concentrations in hyperthyroid cats before (T0) and 3 months after (T1) receiving a PO fixed dose of radioiodine. Animals Eighty client‐owned hyperthyroid cats. Methods Prospective cohort study. Serum TT4, and SDMA, creatinine concentrations, and urine specific gravity were measured at T0 and T1. Nonparametric tests were used to determine the relationship among SDMA, and creatinine and TT4 concentrations. Agreement between SDMA and creatinine regarding CKD staging at both time points was assessed using Goodman and Kruskal's gamma statistic. Results Mean serum SDMA concentration increased after treatment of hyperthyroidism. However, 21 of 75 cats experienced a decrease in SDMA between T0 and T1, whereas creatinine decreased in only 2 cats. A moderate correlation between SDMA and creatinine was seen at T1 (r = 0.53; P < .001) but not at T0 (r = 0.13; P = .25). Where assessable at T1, poor agreement was observed between SDMA and creatinine and CKD stage (Goodman and Kruskal's gamma 0.20; P = .29). Conclusions and clinical importance Discordant outcomes between SDMA and creatinine after radioiodine treatment in cats with hyperthyroidism suggest extrarenal factors may interfere with the reliability of SDMA to adequately reflect renal function. As a result, SDMA should not be interpreted in isolation in hyperthyroid cats treated with radioiodine.
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Affiliation(s)
- Lucia Yu
- Translational Research and Small Animal Clinical Trial Study Group, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Lauren Lacorcia
- Translational Research and Small Animal Clinical Trial Study Group, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Sue Finch
- Statistical Consulting Centre and Melbourne Statistical Consulting Centre, The University of Melbourne, Victoria, Australia
| | - Thurid Johnstone
- Translational Research and Small Animal Clinical Trial Study Group, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
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22
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DeMonaco SM, Panciera DL, Morre WA, Conway T, Werre S. Symmetric dimethylarginine in hyperthyroid cats before and after treatment with radioactive iodine. J Feline Med Surg 2020; 22:531-538. [PMID: 31290362 PMCID: PMC10814339 DOI: 10.1177/1098612x19859947] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES The purpose of this study was to evaluate symmetric dimethylarginine (SDMA) in hyperthyroid cats before and after treatment with radioactive iodine and to determine how pretreatment SDMA relates to the development of post-treatment azotemia. METHODS Eighty-four non-azotemic hyperthyroid cats had serum SDMA and creatinine evaluated before and 1, 3 and 6 months after treatment with radioiodine therapy. RESULTS Baseline SDMA was increased in 7% (n = 6/84) of cats, whereas SDMA was increased in 19% (n = 15/81), 20% (n = 16/80) and 32% (n = 26/81) at 1 month, 3 months and 6 months after treatment, respectively. Creatinine was not elevated in any of the cats at baseline because of the study design, and was elevated in 6% (n = 5/81), 15% (n = 12/80) and 15% (n = 12/81) of cats at 1, 3 and 6 months after treatment, respectively. SDMA (median 11 μg/dl, range 1-22 μg/dl) was significantly higher at 3 (12 μg/dl, range 6-45 μg/dl; P = 0.005) and 6 months (11 μg/dl, 6-25 μg/dl; P <0.001) compared with baseline (11 μg /dl, range 1-21 μg/dl). The median baseline SDMA was significantly higher in the azotemic group (13 μg/dl, range 11-22 μg/dl) compared with the non-azotemic group (10 μg/dl, range 1-21 μg/dl, P = 0.002). The sensitivity of SDMA for detecting azotemia after treatment was 15.4%, with a specificity of 94.4%. Baseline serum SDMA concentration had a moderately positive association with baseline creatinine concentration (P <0.001, r = 0.437). At 6 months, there was a strong positive correlation between SDMA and creatinine concentrations (P <0.001, r = 0.721). There was no significant correlation with SDMA and thyroxine at baseline (P = 0.772, r = -0.034) or 6 months (P = 0.492, r = -0.078). CONCLUSIONS AND RELEVANCE SDMA increases in cats treated for hyperthyroidism with radioactive iodine and likely reflects associated changes in glomerular filtration rate. An increased SDMA concentration above the reference interval prior to treatment has a high specificity but poor sensitivity for the prediction of post-treatment azotemia.
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Affiliation(s)
- Stefanie M DeMonaco
- Department of Small Animal Clinical Sciences, Virginia–Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - David L Panciera
- Department of Small Animal Clinical Sciences, Virginia–Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Wendy A Morre
- Department of Small Animal Clinical Sciences, Virginia–Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Tina Conway
- Small Animal Internal Medicine, Veterinary Referral Associates, Gaithersburg, MD, USA
| | - Stephen Werre
- Laboratory for Study Design and Statistical Analysis, Virginia–Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
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23
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Cui Y, Heuser K, Bauer N, Neiger R. Coagulation parameters in hyperthyroid cats before and after radioiodine treatment compared with healthy controls. J Feline Med Surg 2019; 21:1134-1140. [PMID: 30571457 PMCID: PMC10814272 DOI: 10.1177/1098612x18820145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
OBJECTIVES The aim of the study was to describe the coagulatory state of hyperthyroid cats before and after successful radioiodine therapy (RIT) compared with healthy age-matched controls, using classical coagulation parameters and thromboelastogram (TEG) as a global assessment method. The differences in coagulation activity after RIT, depending on the thyroid hormone (normal vs low total thyroxine [T4]) state, were also evaluated. METHODS Fifteen hyperthyroid cats and 10 healthy age-matched controls were recruited. Hyperthyroid cats that remained hyperthyroid 14 days after RIT were excluded. Haematology, biochemistry, T4, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and TEG were assessed in control cats and hyperthyroid cats before and 7 and 14 days after RIT. Two weeks after successful RIT, further comparisons were made between cats with normal T4 vs those with low T4. RESULTS Fourteen days after successful RIT, 7/15 cats had normal T4 and 8/15 had low T4. Thrombocytosis was noted in 6/15 cats after treatment. Fibrinogen was significantly higher (P <0.001) and PT shorter (P <0.01) in the hyperthyroid cats compared with the healthy controls and these changes persisted after RIT. Persistent increases in fibrinogen, PT, TEG maximal amplitude and TEG clot rigidity, reflecting clot stability, after RIT primarily occurred in the cats with normal T4. TEG-K (time until preset amplitude of 20 mm is reached) and alpha (α) angle reflected impaired fibrin cross-linking ability prior to RIT, which significantly increased after therapy (P <0.05). CONCLUSIONS AND RELEVANCE Based on some of the coagulation parameters, cats with hyperthyroidism showed hypercoagulable tendencies, which were mildly increased after RIT, possibly due to transient radiation-induced thyroiditis.
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Affiliation(s)
- Yi Cui
- Department of Veterinary Clinical Sciences, Small Animal Internal Medicine, Justus-Liebig University, Giessen, Germany
| | - Katharina Heuser
- Department of Veterinary Clinical Sciences, Small Animal Internal Medicine, Justus-Liebig University, Giessen, Germany
| | - Natali Bauer
- Department of Veterinary Clinical Sciences, Small Animal Internal Medicine, Justus-Liebig University, Giessen, Germany
| | - Reto Neiger
- Small Animal Clinic Hofheim, Hofheim, Germany
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24
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Fernandez Y, Puig J, Powell R, Seth M. Prevalence of iatrogenic hypothyroidism in hyperthyroid cats treated with radioiodine using an individualised scoring system. J Feline Med Surg 2019; 21:1149-1156. [PMID: 30667287 PMCID: PMC10814268 DOI: 10.1177/1098612x18822396] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
OBJECTIVES The aim of this study was to report the prevalence of iatrogenic hypothyroidism, with or without azotaemia, based on the measurement of serum total thyroxine (T4), thyroid-stimulating hormone (TSH) and creatinine concentrations, in hyperthyroid cats undergoing radioiodine (131I) treatment where the 131I dose was calculated using a previously described scoring system. A secondary aim of the study was to determine the positive and negative predictive values of serum T4 and TSH concentrations obtained 19 days after treatment in order to predict the development of iatrogenic hypothyroidism 6-9 months after 131I treatment. METHODS Serum T4, TSH and creatinine concentrations were measured 19 days and 6-9 months after 131I treatment. The prevalence of iatrogenic hypothyroidism was assessed with the results obtained 6-9 months after 131I treatment. RESULTS The prevalence of overt and subclinical hypothyroidism 6-9 months after 131I treatment was 40.0% (22/55 cats) and 12.7% (7/55 cats). Overt hypothyroidism with azotaemia was diagnosed in 8/55 (14.5%) cats. The positive and negative predictive values for the prediction of the development of iatrogenic hypothyroidism 6-9 months after 131I treatment were 72.2% and 80.0%, respectively, for a low serum T4 concentration, and 75.0% and 44.6%, respectively, for an increased serum TSH concentration. CONCLUSIONS AND RELEVANCE The use of an individualised scoring system is effective in determining the 131I dose for the treatment of hyperthyroid cats. However, the prevalence of overt hypothyroidism was higher in comparison with other studies using different dosing protocols. Further studies comparing the efficacy of individualised scoring systems and different fixed doses to determine which method is superior are warranted.
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Affiliation(s)
- Yordan Fernandez
- Centre for Small Animal Studies, Animal Health Trust, Newmarket, UK
| | - Jordi Puig
- Centre for Small Animal Studies, Animal Health Trust, Newmarket, UK
| | - Roger Powell
- Powell Torrance Diagnostic Services, Higham Gobion, UK
| | - Mayank Seth
- Centre for Small Animal Studies, Animal Health Trust, Newmarket, UK
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25
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Finch NC, Stallwood J, Tasker S, Hibbert A. Thyroid and renal function in cats following low-dose radioiodine (111Mbq) therapy. J Small Anim Pract 2019; 60:523-528. [PMID: 31328277 DOI: 10.1111/jsap.13057] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 05/16/2019] [Accepted: 06/17/2019] [Indexed: 02/06/2023]
Abstract
OBJECTIVES To describe the effect of low-dose (111MBq) radioiodine therapy on thyroid and renal function in hyperthyroid cats over a 12-month follow-up period. MATERIALS AND METHODS Client-owned hyperthyroid cats underwent low-dose radioiodine therapy and were followed-up for 12 months. Immediately before radioiodine treatment, and at 1, 6 and 12 months afterwards, total thyroxine, thyroid stimulating hormone, serum creatinine and glomerular filtration rate were measured. RESULTS Fifteen of the 24 (63%) cats achieved euthyroidism following low-dose radioiodine treatment. The incidence of overt hypothyroidism was six of 24 (25%) cats. Of the six cats developing overt hypothyroidism, three had decreased renal function, with decreased glomerular filtration rate preceding azotaemia in two of these individuals. Transient overt or subclinical hypothyroidism before restoration of euthyroidism was not observed. CLINICAL SIGNIFICANCE Low-dose radioiodine is effective treatment for hyperthyroidism in most cats but overt hypothyroidism may develop in some. Concurrent early decline in renal function may only be detected by measuring glomerular filtration rate rather than serum creatinine in some cats. Monitoring following radioiodine treatment should include total thyroxine and thyroid stimulating hormone and measurement of glomerular filtration rate should be considered in non-azotaemic cats.
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Affiliation(s)
- N C Finch
- Bristol Veterinary School, University of Bristol, Bristol, BS40 5DU, UK.,Bristol Renal, Bristol Medical School, University of Bristol, Bristol, BS1 3NY, UK
| | - J Stallwood
- Bristol Veterinary School, University of Bristol, Bristol, BS40 5DU, UK
| | - S Tasker
- Bristol Veterinary School, University of Bristol, Bristol, BS40 5DU, UK.,The Feline Centre, Langford Vets, University of Bristol, Bristol, BS40 5DU, UK
| | - A Hibbert
- The Feline Centre, Langford Vets, University of Bristol, Bristol, BS40 5DU, UK
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26
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Lattimer JC, Selting KA, Lunceford JM, Holland JR, Simon J, Stevenson NR, Doerr CA. Intraarticular injection of a Tin-117 m radiosynoviorthesis agent in normal canine elbows causes no adverse effects. Vet Radiol Ultrasound 2019; 60:567-574. [PMID: 31155782 DOI: 10.1111/vru.12757] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 01/31/2019] [Accepted: 03/20/2019] [Indexed: 01/15/2023] Open
Abstract
This longitudinal prospective exploratory study used serial measurements in five dogs to evaluate safety and retention of a tin-117 m (117m Sn) colloid after intra-articular injection in normal elbow joints. Each dog was deemed healthy based on physical examination, laboratory results, and radiographic evaluation of both elbows. While anesthetized, each received an MRI of both elbows, followed by fluorine-18 fluorodeoxyglucose positron emission tomography scans of both elbow joints and associated lymph nodes. Joint fluid (0.5-1.0 mL) was withdrawn aseptically from the left elbow joint, followed by intra-articular injection of 117m Sn colloid (92.5 MBq; 1-1.5 ml). Post-injection assessments included blood counts, serum chemistry panels, urinalyses, radiographs, joint fluid analyses, MRI/positron emission tomography scans, scintigraphy, and biodistribution scans. On day 45-47, each dog was euthanized and a complete postmortem examination was performed. Tissue samples were submitted for histopathology and radioisotope retention studies. Left elbow joints were decalcified and sectioned for future autoradiography. Scintigraphy, 1 day after injection, indicated slight radioisotope escape from the joint to regional lymph nodes. Serial blood, urine, feces, and organ counts indicated >99.1% of the 117m Sn activity was retained in the joint for 45-47 days. Radiation output levels were below patient release levels the day following injection. Maximum standard uptake value for the injected joint decreased. Joint fluid cytology was unchanged. No dog exhibited lameness during the study. Absence of joint damage and lack of systemic effects after injection of the 117m Sn colloid in normal canine elbow joints indicate that this agent may be safely used for radiosynoviorthesis in dogs with osteoarthritis.
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Affiliation(s)
- Jimmy C Lattimer
- Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, Missouri
| | - Kimberly A Selting
- Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, Missouri.,Department of Veterinary Clinical Medicine, University of Illinois, Urbana, Illinois
| | - Joni M Lunceford
- Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, Missouri
| | - James R Holland
- Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, Missouri
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27
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Buresova E, Stock E, Paepe D, Stammeleer L, Vandermeulen E, Smets P, Duchateau L, Lefebvre HP, Daminet S. Assessment of symmetric dimethylarginine as a biomarker of renal function in hyperthyroid cats treated with radioiodine. J Vet Intern Med 2019; 33:516-522. [PMID: 30632628 PMCID: PMC6430927 DOI: 10.1111/jvim.15407] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/29/2018] [Indexed: 12/27/2022] Open
Abstract
Background Measurement of serum creatinine (sCr) and urea nitrogen fail to detect decreased renal function in many hyperthyroid cats because of low muscle mass and glomerular hyperfiltration of affected cats. Serum symmetric dimethylarginine (sSDMA) is an earlier and more sensitive renal biomarker than sCr. Objective Evaluate sSDMA as a biomarker of renal function in hyperthyroid cats before (T0) and 1 month after (T1) radioiodine (131I) treatment. Animals Forty‐seven client‐owned hyperthyroid nonazotemic cats were evaluated at T0 and T1. Methods A prospective study in which sCr and sSDMA concentrations were determined in 47 hyperthyroid cats at T0 and at T1. Glomerular filtration rate (GFR) was estimated at T0 and T1 in 10 of these 47 cats using plasma exogenous creatinine clearance test. Results Serum SDMA was elevated (>14 μg/dL) in 6 of 47 cats at T0 and normalized after treatment in 4 of those cats. All cats remained nonazotemic after treatment. In 10 cats in which GFR was measured, correlation between GFR and sSDMA was low and not significant (τb = −0.35, P = .17 at T0 and τb = −.22, P = .41 at T1), whereas correlation between GFR and sCr was moderate and significant (τb = −0.52, P < .05 at T0 and τb = −.53, P = <.05 at T1). Conclusions and Clinical Importance Careful interpretation of mildly increased sSDMA with normal sCr in hyperthyroid cats is warranted as sSDMA values might normalize after resolution of hyperthyroidism in some cats. In this population of hyperthyroid cats, sSDMA was poorly correlated with GFR.
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Affiliation(s)
- Eva Buresova
- The Small Animal Department, Ghent University, Merelbeke, Belgium
| | - Emmelie Stock
- The Department of Medical Imaging of Domestic Animals, Ghent University, Merelbeke, Belgium
| | - Dominique Paepe
- The Small Animal Department, Ghent University, Merelbeke, Belgium
| | - Lisa Stammeleer
- The Small Animal Department, Ghent University, Merelbeke, Belgium
| | - Eva Vandermeulen
- The Department of Medical Imaging of Domestic Animals, Ghent University, Merelbeke, Belgium
| | - Pascale Smets
- The Small Animal Department, Ghent University, Merelbeke, Belgium
| | - Luc Duchateau
- The Biometrics Research Group, Ghent University, Merelbeke, Belgium
| | - Herve P Lefebvre
- The Department of Physiology, École Nationale Vétérinaire de Toulouse, Toulouse, France
| | - Sylvie Daminet
- The Small Animal Department, Ghent University, Merelbeke, Belgium
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28
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Watson N, Murray JK, Fonfara S, Hibbert A. Clinicopathological features and comorbidities of cats with mild, moderate or severe hyperthyroidism: a radioiodine referral population. J Feline Med Surg 2018; 20:1130-1137. [PMID: 29432704 PMCID: PMC11104204 DOI: 10.1177/1098612x18755925] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2018] [Indexed: 12/26/2022]
Abstract
OBJECTIVES This study sought to explore the clinicopathological features and comorbidities of cats with mild, moderate and severe hyperthyroidism in a radioiodine referral population. METHODS Medical records were reviewed, along with results of serum biochemistry, urinalysis, systolic blood pressure and diagnostic imaging performed at the time of radioiodine referral. Cats were grouped by total thyroxine (TT4) levels as mildly (TT4 60.1-124.9 nmol/l), moderately (TT4 125-250 nmol/l) or severely (TT4 >250 nmol/l) hyperthyroid at the time of diagnosis and referral. RESULTS Thirty percent (42/140) of the cats were <10 years old at diagnosis. In 24.3% (34/140), hyperthyroidism was diagnosed incidentally. The time between diagnosis and referral for radioiodine was significantly longer in cats with severe hyperthyroidism at the time of referral ( P = 0.004). An increase in severity group between the time of diagnosis and referral occurred in 38.6% (54/140) of cats. At referral, 54.3% (25/46) of cats with mild, 66.7% (42/63) with moderate and 80.6% (25/31) with severe hyperthyroidism were unstable despite ongoing medical or dietary management. The prevalence of cardiac abnormalities was significantly increased in cats with severe hyperthyroidism ( P = 0.014) compared with those with mild or moderate hyperthyroidism. There was no significant difference in the likelihood of renal disease ( P = 0.708) or hypertension ( P = 0.328) between the groups. CONCLUSIONS AND RELEVANCE Incidental diagnosis of hyperthyroidism occurs commonly, potentially owing to increased disease screening. Cats with severe hyperthyroidism at referral were more likely to be chronically hyperthyroid with a history of poor stabilisation. This subset of patients was significantly more likely to have cardiac abnormalities. Thyrotoxic cardiomyopathy may ultimately affect patient suitability for curative treatments (radioiodine or thyroidectomy) owing to higher anaesthetic risks and potential for decompensation into congestive heart failure with the stress of travel and hospitalisation. Curative therapy should be considered before the development of severe hyperthyroidism.
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Affiliation(s)
- Natalie Watson
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - Jane K Murray
- School of Veterinary Sciences, University of Bristol, Bristol, UK
- Dogs Trust, London, UK
| | - Sonja Fonfara
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, ON, Canada
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29
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Oberstadt AE, Nelson NC, Claude AK, Refsal KR, Scott‐Moncrieff JC, Petroff BK, Langlois DK. Radioactive iodine uptake in hyperthyroid cats after administration of recombinant human thyroid stimulating hormone. J Vet Intern Med 2018; 32:1891-1896. [PMID: 30315668 PMCID: PMC6271304 DOI: 10.1111/jvim.15295] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 07/02/2018] [Accepted: 07/17/2018] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Radioactive iodine therapy is considered the treatment of choice for hyperthyroidism in cats, but the availability of this modality is limited by costs and hospitalization requirements. Administration of recombinant human thyroid stimulating hormone (rh-TSH) to humans with thyroid neoplasia or nodular goiter can increase thyroidal iodine uptake, thereby allowing the use of lower radioactive iodine doses for treatment. Veterinary studies of this subject are limited, and results are conflicting. OBJECTIVE To investigate the effects of rh-TSH administration on thyroidal iodine uptake in hyperthyroid cats. ANIMALS Ten client-owned hyperthyroid cats. METHODS In this prospective clinical study, cats were administered saline (placebo), 50 μg rh-TSH (low-dose), and 100 μg rh-TSH (high-dose) in randomized crossover design with treatments separated by 7-10 days. After each treatment, thyroid scintigraphy was performed by administering 300 μCi 123 I and assessing radionuclide uptake 8 and 24 hours later. Serum thyroid hormone concentrations were measured at each visit. RESULTS Thyroidal percent iodine uptakes (mean ± SD at 8 and 24 hours) in cats treated with placebo (25.2 ± 13.4%, 30.0 ± 12.8%), low-dose (24.1 ± 12.5%, 29.4 ± 13.7%), and high-dose rh-TSH (24.2 ± 16.3%, 30.8 ± 15.3%) were not different (P = .76). Independent of rh-TSH administration, percent iodine uptakes were positively correlated with serum thyroid hormone concentrations. CONCLUSIONS AND CLINICAL IMPORTANCE One-time administration of rh-TSH, even at high doses, would not be expected to lower radioactive iodine doses needed for treatment of hyperthyroidism in cats. Investigations of alternate strategies to increase thyroidal uptake of radioactive iodine are warranted.
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Affiliation(s)
- Amy E. Oberstadt
- Departments of Small Animal Clinical SciencesCollege of Veterinary Medicine, Michigan State UniversityEast LansingMichigan48824
| | - Nathan C. Nelson
- Departments of Small Animal Clinical SciencesCollege of Veterinary Medicine, Michigan State UniversityEast LansingMichigan48824
| | - Andrew K. Claude
- Departments of Small Animal Clinical SciencesCollege of Veterinary Medicine, Michigan State UniversityEast LansingMichigan48824
| | - Kent R. Refsal
- Pathobiology and Diagnostic InvestigationCollege of Veterinary Medicine, Michigan State UniversityEast LansingMichigan48824
| | - J. Catharine Scott‐Moncrieff
- Department of Veterinary Clinical SciencesCollege of Veterinary Medicine, Purdue UniversityWest LafayetteIndiana47907
| | - Brian K. Petroff
- Pathobiology and Diagnostic InvestigationCollege of Veterinary Medicine, Michigan State UniversityEast LansingMichigan48824
| | - Daniel K. Langlois
- Departments of Small Animal Clinical SciencesCollege of Veterinary Medicine, Michigan State UniversityEast LansingMichigan48824
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30
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Peterson ME, Carothers MA, Gamble DA, Rishniw M. Spontaneous primary hypothyroidism in 7 adult cats. J Vet Intern Med 2018; 32:1864-1873. [PMID: 30294940 PMCID: PMC6271337 DOI: 10.1111/jvim.15239] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 04/10/2018] [Accepted: 05/15/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Naturally occurring hypothyroidism in adult cats is rare, with only 4 cases reported. OBJECTIVES To describe the historical, clinical, laboratory, and scintigraphic features of adult cats with spontaneous hypothyroidism. ANIMALS Seven adult cats referred for suspected hypothyroidism. METHODS Prospective case series. We collected data on cats' signalment, clinical signs, results of physical examination, routine laboratory and thyroid hormone testing, and thyroid imaging (thyroid scintigraphy or ultrasound). We subsequently treated cats with levothyroxine and evaluated their response to treatment. RESULTS Cats ranged from 3.5 to 11 years, with no apparent breed predilection; 6/7 cats were male. Only 2/7 cats were initially tested because of signs of hypothyroidism (hair-coat changes, lethargy, obesity); others were tested for routine thyroid monitoring or palpable thyroid nodules. Four were azotemic (serum creatinine, 2.2-3.4 mg/dL). Six of the cats had low serum thyroxine (T4 ) and free T4 (fT4 ) concentrations, whereas all 7 cats had high thyroid-stimulating hormone (TSH) concentrations. In 6/7 cats, thyroid scintigraphy revealed bilateral goiter with intense radionuclide uptake; imaging showed no visible thyroid tissue in the other. After levothyroxine treatment, serum concentrations of T4 and fT4 increased and TSH fell; high serum creatinine normalized in azotemic cats; and repeat imaging showed reduction in goiter size. CONCLUSIONS AND CLINICAL IMPORTANCE Primary hypothyroidism develops in adult cats, with a higher prevalence than previously thought. Most cats appear to develop a goitrous form of hypothyroidism associated with thyroid hyperplasia, whereas thyroid atrophy appears to be less common. With levothyroxine replacement, clinical and laboratory abnormalities improve or resolve.
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Affiliation(s)
- Mark E. Peterson
- Animal Endocrine ClinicNew York
- College of Veterinary MedicineCornell UniversityIthacaNew York
| | | | | | - Mark Rishniw
- College of Veterinary MedicineCornell UniversityIthacaNew York
- Veterinary Information NetworkDavisCalifornia
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31
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Morré WA, Panciera DL, Daniel GB, Monroe WE, Werre S. Investigation of a novel variable dosing protocol for radioiodine treatment of feline hyperthyroidism. J Vet Intern Med 2018; 32:1856-1863. [PMID: 30328158 PMCID: PMC6271315 DOI: 10.1111/jvim.15296] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 05/21/2018] [Accepted: 07/17/2018] [Indexed: 12/03/2022] Open
Abstract
Background Radioiodine is the treatment of choice for hyperthyroidism in cats. The ideal method of dose determination of radioiodine remains controversial. Objective To compare a method of radioiodine dose determination that utilized thyroid scintigraphy with a standard fixed dose for treatment of hyperthyroidism. Animals Fifty‐seven and 23 client‐owned hyperthyroid cats in the variable and fixed dose groups, respectively. Methods Cats with a percent dose uptake using 99mTc‐pertechnetate uptake on thyroid scintigraphy <5%, 5%‐10%, and >10% were to receive 3, 3.5, or 4.5 millicuries (mCi) of radioiodine, respectively, administered SC. Radioiodine dose was adjusted according to thyroid gland size as determined by the thyroid:salivary size ratio and categorized as <5:1, 5‐10:1, and >10:1. If the thyroid size fell into a higher dosing category than the percent dose uptake, the dose was increased accordingly. Cats in the fixed dose group received 4.5 mCi. Six months after treatment, cats were determined to be euthyroid, hypothyroid, or hyperthyroid based on serum thyroxine and thyroid stimulating hormone concentrations. Results No difference in outcome was found between the variable and fixed dose treatment groups. Euthyroidism, hypothyroidism, and persistent hyperthyroidism developed in 61, 30, and 9% of cats in the fixed dose group compared to 58, 26, and 16%, respectively, in the variable dose group. Conclusions A variable dosing method of radioiodine based on percent dose uptake primarily and thyroid gland size secondarily did not improve outcome compared to a standard fixed dose method.
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Affiliation(s)
- Wendy A Morré
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia
| | - David L Panciera
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia
| | - Gregory B Daniel
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia
| | - William E Monroe
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia
| | - Stephen Werre
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia
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32
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Vagney M, Desquilbet L, Reyes-Gomez E, Delisle F, Devauchelle P, Rodriguez-Piñeiro MI, Rosenberg D, de Fornel-Thibaud P. Survival times for cats with hyperthyroidism treated with a 3.35 mCi iodine-131 dose: a retrospective study of 96 cases. J Feline Med Surg 2018; 20:528-534. [PMID: 28699814 PMCID: PMC11104074 DOI: 10.1177/1098612x17718416] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Objectives Radioiodine (131I) dose determination using radiotracer kinetic studies or scoring systems, and fixed relatively high 131I dose (ie, 4 or 5 mCi) administration, are effective and associated with prolonged survival times for hyperthyroid cats. The latter method is less complicated but could expose patients and veterinary personnel to unnecessary levels of radiation. The aim of this study was to retrospectively evaluate the efficacy of a fixed 3.35 mCi 131I dose for the treatment of 96 hyperthyroid cats with no length estimation for any palpated goitre ⩾20 mm, assess outcome and identify factors associated with survival. Methods Serum total thyroxine concentrations at diagnosis and at follow-up times, survival times and cause of death were recorded. Multivariable Cox regression analysis was used to identify factors associated with time to any cause of death from 131I therapy initiation. Results Administration of a median (interquartile range) dose of 3.35 mCi (3.27-3.44 mCi) radioiodine was an effective treatment in 94/96 cats, but two cats remained hyperthyroid. No death related to hyperthyroidism was recorded. Median survival time was 3.0 years; the 1 and 2 year survival rates after 131I therapy were 90% and 78%, respectively. Low body weight (⩽3.1 kg; adjusted hazard ratio [aHR] 5.88; 95% confidence interval [CI] 2.22-16.67; P <0.01) and male gender (aHR 2.63; 95% CI 1.01-7.14; P = 0.04) were independently associated with death, whereas age, prior treatment with antithyroid drugs, reason for treatment and pretreatment azotaemia were not. Conclusions and relevance This study suggests that a fixed 3.35 mCi 131I dose treatment is effective for hyperthyroid cats with goitre(s) with a maximal length estimation <20 mm, that long-term survival can be achieved and that low body weight and male gender are significantly associated with shorter survival times.
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Affiliation(s)
| | - Loic Desquilbet
- University of Paris-Est, National Veterinary School of Alfort, Clinical Epidemiology and Biostatistics Unit, Maisons Alfort, France
| | - Edouard Reyes-Gomez
- University of Paris-Est, National Veterinary School of Alfort, BioPôle, Anatomical Pathology Unit, Maisons Alfort, France, and Faculty of Medicine, Créteil, France
- Inserm, IMRB U955-E10, Créteil, France
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Peterson ME, Rishniw M, Bilbrough GE, Cote KB. Comparison of in-clinic point-of-care and reference laboratory total thyroxine immunoassays for diagnosis and post-treatment monitoring of hyperthyroid cats. J Feline Med Surg 2018; 20:319-324. [PMID: 28494633 PMCID: PMC11129217 DOI: 10.1177/1098612x17708918] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Objectives The Catalyst One Chemistry Analyzer (IDEXX Laboratories) is a point-of-care instrument that can measure total thyroxine (TT4) by immunoassay. The aims of this study were to evaluate the analytic performance of the Catalyst TT4 assay in feline sera and to examine agreement of the Catalyst TT4 results with those measured by immunoassay at a veterinary reference laboratory. Methods Assay precision, reproducibility and linearity were evaluated for the Catalyst TT4 assay. For method comparison, TT4 concentrations in serum samples from 157 cats (127 hyperthyroid, 30 radioiodine-treated cats) were analyzed by both in-clinic and reference laboratory methods. Results The Catalyst TT4 demonstrated good precision and reproducibility (coefficients of variation ⩽8.5%) and excellent linearity in the diagnostic range of 6-150 nmol/l. Differences between the two TT4 methods showed no proportional or fixed bias (Bland-Altman plots) but did demonstrate greater spread of values at higher TT4 concentrations. Statistical analysis of percent differences between methods indicated 95% limits of agreement of ± 30%. When serum TT4 concentrations were classified as low, high or within the reference interval (12-50 nmol/l) for each assay, there was strong agreement (96.8%) in classification between methods. Conclusions and relevance The Catalyst TT4 assay provided precise serum TT4 concentrations in the 157 samples analyzed, which agreed well with results provided by a reference laboratory. Cats with Catalyst TT4 concentrations near decision thresholds (eg, normal vs high) should either have TT4 concentration repeated a few weeks later and/or undergo further testing (eg, free T4, serum thyroid-stimulating hormone, thyroid scintigraphy) to determine thyroid status.
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Affiliation(s)
- Mark E Peterson
- Animal Endocrine Clinic, New York, NY, USA
- Cornell University, Ithaca, NY, USA
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Peterson M, Varela F, Rishniw M, Polzin D. Evaluation of Serum Symmetric Dimethylarginine Concentration as a Marker for Masked Chronic Kidney Disease in Cats With Hyperthyroidism. J Vet Intern Med 2018; 32:295-304. [PMID: 29377360 PMCID: PMC5787157 DOI: 10.1111/jvim.15036] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 09/28/2017] [Accepted: 11/30/2017] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Hyperthyroidism can complicate (mask) the diagnosis of chronic kidney disease (CKD) because it increases glomerular filtration rate and decreases body muscle mass, both of which can lower serum creatinine concentrations. Currently, there is no clinical test that can reliably predict which hyperthyroid cats have concurrent azotemic CKD that will become apparent after treatment of the hyperthyroidism. OBJECTIVES To investigate serum symmetric dimethylarginine (SDMA) concentration as a potential marker of masked azotemia in untreated hyperthyroid cats. ANIMALS Two hundred and sixty-two hyperthyroid cats and 206 aged-matched, clinically normal cats. METHODS Prospective study. We measured creatinine, urea nitrogen, SDMA, T4 , and TSH concentrations before and 1, 3, and 6 months after treatment with radioiodine (131 I) and classified 131 I-treated cats as azotemic or nonazotemic based on persistent, post-treatment creatinine concentrations >2.1 mg/dL. Groups were compared via nonparametric tests, and diagnostic accuracy was determined by receiver operating characteristic analysis and logistic regression. RESULTS No hyperthyroid cats were azotemic before treatment, but 42 (16%) became azotemic when rechecked at 4-8 months (median, 6 months) after 131 I treatment; of these, 14 had high SDMA concentrations before treatment. As a diagnostic test for pre-azotemic (masked) CKD in untreated hyperthyroid cats, SDMA showed a sensitivity of 33.3% and specificity of 97.7%. CONCLUSIONS AND CLINICAL IMPORTANCE Finding a high serum SDMA concentration in a hyperthyroid cat can help predict development of azotemia after treatment. The test has high diagnostic test specificity (few false-positive results) but relatively low sensitivity (fails to predict azotemia in most hyperthyroid cats).
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Affiliation(s)
- M.E. Peterson
- Animal Endocrine Clinic New YorkNY
- College of Veterinary Medicine Cornell UniversityIthacaNY
| | | | - M. Rishniw
- College of Veterinary Medicine Cornell UniversityIthacaNY
- Veterinary Information Network DavisCA
| | - D.J. Polzin
- University of Minnesota College of Veterinary Medicine St. PaulMN
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Peterson ME, Nichols R, Rishniw M. Serum thyroxine and thyroid-stimulating hormone concentration in hyperthyroid cats that develop azotaemia after radioiodine therapy. J Small Anim Pract 2017; 58:519-530. [DOI: 10.1111/jsap.12695] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/10/2017] [Accepted: 04/14/2017] [Indexed: 02/01/2023]
Affiliation(s)
- M. E. Peterson
- Animal Endocrine Clinic; New York NY 10025 USA
- Department of Clinical Sciences, College of Veterinary Medicine; Cornell University; Ithaca NY 14853 USA
| | - R. Nichols
- Animal Endocrine Clinic; New York NY 10025 USA
- Antech Diagnostics; Lake Success NY 11042 USA
| | - M. Rishniw
- Department of Clinical Sciences, College of Veterinary Medicine; Cornell University; Ithaca NY 14853 USA
- Veterinary Information Network; Davis CA 95615 USA
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Carney HC, Ward CR, Bailey SJ, Bruyette D, Dennis S, Ferguson D, Hinc A, Rucinsky AR. 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism. J Feline Med Surg 2016; 18:400-16. [PMID: 27143042 PMCID: PMC11132203 DOI: 10.1177/1098612x16643252] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
CLINICAL CONTEXT Since 1979 and 1980 when the first reports of clinical feline hyperthyroidism (FHT) appeared in the literature, our understanding of the disease has evolved tremendously. Initially, FHT was a disease that only referral clinicians treated. Now it is a disease that primary clinicians routinely manage. Inclusion of the measurement of total thyroxine concentration in senior wellness panels, as well as in diagnostic work-ups for sick cats, now enables diagnosis of the condition long before the cat becomes the classic scrawny, unkempt, agitated patient with a bulge in its neck. However, earlier recognition of the problem has given rise to several related questions: how to recognize the health significance of the early presentations of the disease; how early to treat the disease; whether to treat FHT when comorbid conditions are present; and how to manage comorbid conditions such as chronic kidney disease and cardiac disease with treatment of FHT. The 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism (hereafter referred to as the Guidelines) will shed light on these questions for the general practitioner and suggest when referral may benefit the cat. SCOPE The Guidelines explain FHT as a primary disease process with compounding factors, and provide a concise explanation of what we know to be true about the etiology and pathogenesis of the disease.The Guidelines also:Distill the current research literature into simple recommendations for testing sequences that will avoid misdiagnosis and separate an FHT diagnosis into six clinical categories with associated management strategies.Emphasize the importance of treating all hyperthyroid cats, regardless of comorbidities, and outline the currently available treatments for the disease.Explain how to monitor the treated cat to help avoid exacerbating comorbid diseases.Dispel some of the myths surrounding certain aspects of FHT and replace them with an evidence-based narrative that veterinarians and their practice teams can apply to feline patients and communicate to their owners. EVIDENCE BASE To help ensure better case outcomes, the Guidelines reflect currently available, evidenced-based knowledge. If research is lacking, or if a consensus does not exist, the expert panel of authors has made recommendations based on their extensive, cumulative clinical experience.
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Affiliation(s)
- Hazel C Carney
- WestVet Emergency and Specialty Center, 5019 North Sawyer Avenue, Garden City, ID 83617, USA
| | - Cynthia R Ward
- University of Georgia, College of Veterinary Medicine, 2200 College Station Road, Athens, GA 30605,USA
| | - Steven J Bailey
- Exclusively Cats Veterinary Hospital, 6650 Highland Road, Ste 116, Waterford, MI 48327, USA
| | - David Bruyette
- VCA West Los Angeles Animal Hospital, 1900 South Sepulveda Blvd, Los Angeles, CA 90025, USA
| | - Sonnya Dennis
- Stratham-Newfields Veterinary Hospital, 8 Main Street, Newfields, NH 03856, USA
| | - Duncan Ferguson
- College of Veterinary Medicine - University of Illinois, Department of Comparative Biosciences, 3840 Veterinary Medicine Basic Sciences Bldg, 2001 South Lincoln Avenue, Urbana, IL 61802, USA
| | - Amy Hinc
- Cosmic Cat Veterinary Clinic, 220 East Main Street, Branford, CT 06405, USA
| | - A Renee Rucinsky
- Mid Atlantic Cat Hospital, 201 Grange Hall Road, Queenstown, MD 21658, USA
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