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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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Van Vertloo LR, Palerme JS, Miles KG, Bourgois-Mochel A, Jergens AE. Changes in symmetric dimethylarginine and glomerular filtration rates in hyperthyroid cats undergoing radioiodine therapy. J Feline Med Surg 2023; 25:1098612X231160128. [PMID: 36892005 PMCID: PMC10812008 DOI: 10.1177/1098612x231160128] [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: 03/10/2023]
Abstract
OBJECTIVES The aims of this study were to evaluate concentrations of symmetric dimethylarginine (SDMA) in hyperthyroid cats before and after radioiodine treatment, and to compare results with other variables used to assess kidney function in cats (creatinine, urine specific gravity [USG] and glomerular filtration rate [GFR] measured by renal scintigraphy). METHODS Thirteen cats diagnosed with hyperthyroidism based on clinical signs and increased serum total thyroxine (TT4) were included in this prospective study. Study design included physical examination, complete blood count, serum chemistry, TT4, urinalysis and SDMA before treatment (T0) and at 1 month (T1) and 3 months post-treatment (T3). GFR was quantified by renal scintigraphy at T0 and T3. RESULTS Median GFR decreased significantly from baseline (3.18 ml/kg/min; range 1.35-4.87) at T3 (2.22 ml/kg/min; range 1.81-3.42 [P = 0.005]). While median creatinine and serum urea nitrogen increased post-treatment (creatinine: T0 = 0.8 mg/dl [range 0.4-1.1], T1 = 1.3 mg/dl [range 0.9-2]; T3 = 1.65 mg/dl [range 0.8-2.8]; P <0.001; serum urea nitrogen: T0 = 23 mg/dl [range 15-26]; T1 = 27 mg/dl [range 20-40]; T3 = 27.5 mg/dl [range 20-36]; P <0.001), SDMA and USG did not change significantly (SDMA: T0 = 11 µg/dl [range 7-15]; T1 = 12 µg/dl [range 6-16]; T3 = 10.5 µg/dl [range 8-21]; P = 0.789; USG: T0 = 1.030 [range 1.011-1.059]; T1 = 1.035 [range 1.012-1.044]; T3 = 1.030 [range 1.007-1.055]; P = 0.792). CONCLUSIONS AND RELEVANCE Our data suggest that factors other than GFR may affect serum SDMA in hyperthyroid cats and that SDMA does not offer an advantage over other biomarkers traditionally used to predict changes in renal function following radioiodine therapy.
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Affiliation(s)
- Laura R Van Vertloo
- Department of Veterinary Clinical Sciences, Iowa State University College of Veterinary Medicine, Ames, IA, USA
| | - Jean-Sébastien Palerme
- Department of Veterinary Clinical Sciences, Iowa State University College of Veterinary Medicine, Ames, IA, USA
| | - Kristina G Miles
- Department of Veterinary Clinical Sciences, Iowa State University College of Veterinary Medicine, Ames, IA, USA
| | - Agnes Bourgois-Mochel
- Department of Veterinary Clinical Sciences, Iowa State University College of Veterinary Medicine, Ames, IA, USA
| | - Albert E Jergens
- Department of Veterinary Clinical Sciences, Iowa State University College of Veterinary Medicine, Ames, IA, USA
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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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Geddes R, Aguiar J. Feline Comorbidities: Balancing hyperthyroidism and concurrent chronic kidney disease. J Feline Med Surg 2022; 24:641-650. [PMID: 35481810 PMCID: PMC11107990 DOI: 10.1177/1098612x221090390] [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: 11/16/2022]
Abstract
PRACTICAL RELEVANCE Both hyperthyroidism and chronic kidney disease (CKD) are common long-term conditions in older cats, which might be diagnosed concurrently or develop at different times. Hyperthyroidism may mask the presence of CKD, and vice versa, by various mechanisms that are described in this review. Hyperthyroidism treatment options should be carefully considered when CKD has also been diagnosed. CLINICAL CHALLENGES Although it can be difficult to diagnose hyperthyroidism and CKD simultaneously, given that one condition may mask the other, it is important to consider the presence of both diseases when examining an older cat presenting with vomiting, weight loss, polyuria/ polydipsia, anorexia or sarcopenia. The concurrent presence of hyperthyroidism and CKD requires careful monitoring of glomerular filtration rate biomarkers, and adequate and prompt support of kidney function when normal thyroid function is re-established. Iatrogenic hypothyroidism is a recognised complication of all of the treatment options for hyperthyroidism, and increases the risk of azotaemia. Therapy with levothyroxine is recommended for cats that are hypothyroid and azotaemic. EVIDENCE BASE The information in this review draws on current literature and guidelines related to the pathophysiology, diagnosis and treatment recommendations for feline hyperthyroidism and CKD.
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Affiliation(s)
- Rebecca Geddes
- Clinical Sciences and Services, Royal Veterinary College, University of London, London, UK
| | - Joana Aguiar
- Dick White Referrals, Station Farm, London Road, Six Mile Bottom, Cambridgeshire, UK
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Protective Effect of Natural Antioxidant Compounds on Methimazole Induced Oxidative Stress in a Feline Kidney Epithelial Cell Line (CRFK). Vet Sci 2021; 8:vetsci8100220. [PMID: 34679050 PMCID: PMC8541200 DOI: 10.3390/vetsci8100220] [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: 09/03/2021] [Revised: 09/28/2021] [Accepted: 10/04/2021] [Indexed: 12/01/2022] Open
Abstract
The treatment of choice for feline hyperthyroidism is the administration of the antithyroid drug methimazole. Both the endocrinopathy and the drug adverse reactions (e.g., hepatotoxicosis, gastrointestinal disorders, and renal injury) are partly due to oxidative stress and redox unbalance. This study investigated the free radical production and the impairment of the antioxidant barrier induced by methimazole in an in vitro model of feline renal epithelium. The protective effects of quercetin and resveratrol were also explored. CRFK cells were incubated with a methimazole concentration equivalent to the maximum plasma levels in orally treated cats (4 µM), in the presence or absence of either one of the two selected antioxidants at different time-points (up to 72 h). Cell viability, ROS production, GSH levels, and mRNA expression of antioxidant enzymes (i.e., CAT, SOD, GPx, and GST) were assessed. Methimazole impaired cell viability and increased ROS levels in a time-dependent manner. Similarly, GSH content and CAT, SOD, and GPx3 expression were higher compared with control cells. Such effects were significantly counteracted by quercetin. These results provide new insights about the mechanisms underlying the methimazole-related side effects frequently observed in hyperthyroid cats. They also support the use of quercetin in the management of feline hyperthyroidism.
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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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Alonzi C, Peak K, Gower L, Walker DJ, Johnson B. Establishing levels of retained radioactivity in cats receiving radioactive iodine treatment. Vet Rec 2021; 189:e196. [PMID: 33818767 DOI: 10.1002/vetr.196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 01/22/2021] [Accepted: 02/05/2021] [Indexed: 11/09/2022]
Abstract
BACKGROUND Radioactive iodine (RAI) is considered the gold standard treatment for feline hyperthyroidism. Currently exposure limits to radiation are regulated by national legislation, therefore the length of the isolation period in hospital for cats receiving radioactive treatment varies according to the place where the radioactive facility is located. The aim of this study was to establish when retained radioactivity decreases in cats receiving subcutaneous I-131 to a level that would allow discharge of cats from the hospital while being compliant with current United Kingdom legislation. METHODS Clinical records of cats treated with subcutaneous I-131 were retrospectively reviewed. Radioactive emission rates were measured using an external probe. Retained radioactivity below 11 MBq at the point of discharge was required by the initial risk assessment to ensure that a 0.3 mSv dose constraint was maintained for owners following standard cat-owner contact restrictions. Average retained activity for each treatment regimen at the time of discharge was calculated. The biological half-life for iodine retention was also calculated. RESULTS Overall, an end activity below 11 MBq was reached at day 11 in 49% of cats, and at day 13 in 91% of cats. These cats were allowed to be discharged according to UK legislation, as long as contact restrictions were applied at home for 2 weeks. CONCLUSION Based on our study, an isolation period of 13 days before allowing discharge of cats treated with subcutaneous RAI (I-131) is compliant with current UK legislation.
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Affiliation(s)
- Consuelo Alonzi
- Department of Internal Medicine, Anderson Moores Veterinary Specialists, Winchester, Hampshire, UK
| | - Kerry Peak
- Department of Internal Medicine, Anderson Moores Veterinary Specialists, Winchester, Hampshire, UK
| | - Lou Gower
- Department of Internal Medicine, Anderson Moores Veterinary Specialists, Winchester, Hampshire, UK
| | - David John Walker
- Department of Internal Medicine, Anderson Moores Veterinary Specialists, Winchester, Hampshire, UK
| | - Ben Johnson
- Southampton University Hospitals NHS Trust, Southampton, Hampshire, UK
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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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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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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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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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13
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A retrospective evaluation of the relationship between symmetric dimethylarginine, creatinine and body weight in hyperthyroid cats. PLoS One 2020; 15:e0227964. [PMID: 31990929 PMCID: PMC6986741 DOI: 10.1371/journal.pone.0227964] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 01/05/2020] [Indexed: 01/20/2023] Open
Abstract
Hyperthyroidism in cats can mask changes in renal function, including chronic kidney disease (CKD), because of hyperfiltration and muscle loss. Symmetric dimethylarginine (SDMA) has been shown to increase earlier than creatinine in cats with renal dysfunction, and, unlike creatinine, SDMA is not impacted by lean muscle mass. The aim of this study was to describe the relationship between SDMA, creatinine, body weight and TT4 over time during treatment of hyperthyroidism. Cats were retrospectively identified from the US IDEXX Reference Laboratories database where TT4, SDMA and creatinine were measured on the same cat at multiple time points. A hyperthyroid treated group was identified (TT4 ≤ 4.7 μg/dL and decreased by a minimum of 2.5 μg/dL) that had body weight and laboratory results available from more than one visit, and was used to evaluate body weight, creatinine, SDMA and TT4 pre-treatment and at 1–30, 31–60, 61–90, 91–120 days post-treatment. Creatinine significantly decreased with increasing concentrations of TT4 (Spearman’s ρ = -0.37, P < 0.001), whereas SDMA did not. Body weight, SDMA and creatinine concentrations significantly increased during the immediate 1–30 day post-treatment period (P < 0.012, P < 0.001, P < 0.001, respectively). During treatment creatinine continued to increase as cats gained weight. In contrast, SDMA remained stable during treatment and was comparable to age-matched control cats. Therefore, SDMA may be a more reliable biomarker of renal function than creatinine in hyperthyroid cats before and during treatment.
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14
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Carrasco RA, Verhoef J, Leonardi CEP, Lanigan EE, Adams GP. Bilateral thyroid follicular compact-cellular carcinoma in a llama. J Vet Diagn Invest 2019; 31:913-916. [PMID: 31646945 DOI: 10.1177/1040638719882734] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
An 18-y-old female llama (Lama glama) in Saskatoon, Saskatchewan was examined during a routine herd check, and a mass was detected in the ventral cervical area just below the angle of the jaw. No clinical signs were evident except for the mass and chronic loss of body condition. Postmortem examination revealed bilateral enlargement of the thyroid gland with multiple cysts. Histopathology of the thyroid gland revealed follicular compact-cellular carcinoma lesions, with infiltration of neoplastic thyroid follicular cells in regional lymph nodes.
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Affiliation(s)
- Rodrigo A Carrasco
- Department of Veterinary Biomedical Sciences (Carrasco, Leonardi, Adams), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Western College of Veterinary Medicine (Lanigan), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Charles River Laboratories Senneville, Senneville, Quebec, Canada (Verhoef)
| | - Jolanda Verhoef
- Department of Veterinary Biomedical Sciences (Carrasco, Leonardi, Adams), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Western College of Veterinary Medicine (Lanigan), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Charles River Laboratories Senneville, Senneville, Quebec, Canada (Verhoef)
| | - Carlos E P Leonardi
- Department of Veterinary Biomedical Sciences (Carrasco, Leonardi, Adams), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Western College of Veterinary Medicine (Lanigan), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Charles River Laboratories Senneville, Senneville, Quebec, Canada (Verhoef)
| | - Emily E Lanigan
- Department of Veterinary Biomedical Sciences (Carrasco, Leonardi, Adams), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Western College of Veterinary Medicine (Lanigan), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Charles River Laboratories Senneville, Senneville, Quebec, Canada (Verhoef)
| | - Gregg P Adams
- Department of Veterinary Biomedical Sciences (Carrasco, Leonardi, Adams), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Western College of Veterinary Medicine (Lanigan), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Charles River Laboratories Senneville, Senneville, Quebec, Canada (Verhoef)
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15
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Trevejo RT, Lefebvre SL, Yang M, Rhoads C, Goldstein G, Lund EM. Survival analysis to evaluate associations between periodontal disease and the risk of development of chronic azotemic kidney disease in cats evaluated at primary care veterinary hospitals. J Am Vet Med Assoc 2019; 252:710-720. [PMID: 29504859 DOI: 10.2460/javma.252.6.710] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To examine potential associations between periodontal disease (PD) and the risk of development of chronic azotemic kidney disease (CKD) among cats and determine whether the risk of CKD increases with severity of PD. DESIGN Retrospective cohort study. ANIMALS 169, 242 cats. PROCEDURES Cats were evaluated ≥ 3 times at any of 829 hospitals from January 1, 2002, through June 30, 2013. Cats with an initial diagnosis of PD of any stage (n = 56,414) were frequency matched with cats that had no history or evidence of PD (112,828) by age and year of study entry. Data on signalment, PD, and other conditions potentially related to CKD were extracted from electronic medical records. Cox proportional hazards modeling was used to estimate the association of PD with CKD after controlling for covariates. RESULTS PD was associated with increased risk of CKD; risk was highest for cats with stage 3 or 4 PD. Risk of CKD increased with age. Purebred cats had greater risk of CKD than mixed-breed cats. General anesthesia within the year before study exit and diagnosis of cystitis at any point prior to study exit (including prior to study entry) were each associated with increased CKD risk. Diagnosis of diabetes mellitus or hepatic lipidosis at any point prior to study exit was associated with decreased CKD risk. CONCLUSIONS AND CLINICAL RELEVANCE The findings supported the benefit of maintaining good oral health and can be useful to veterinarians for educating owners on the importance of preventing PD in cats.
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16
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Covey HL, Chang YM, Elliott J, Syme HM. Changes in thyroid and renal function after bilateral thyroidectomy in cats. J Vet Intern Med 2019; 33:508-515. [PMID: 30758070 PMCID: PMC6430951 DOI: 10.1111/jvim.15450] [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: 05/30/2018] [Accepted: 01/28/2019] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Iatrogenic hypothyroidism might worsen the prognosis of cats with azotemic CKD after thyroidectomy. Varying thyroxine concentrations influence utility of creatinine in assessing renal function. Symmetric dimethylarginine (SDMA) has limited studies in cats with changing thyroid status. OBJECTIVES Thyroid status is stable 6 months post-thyroidectomy. Symmetric dimethylarginine and creatinine are linearly associated without influence from total thyroxine concentration (tT4). ANIMALS Electronic records of 2 first opinion practices were searched using the term "thyroidectomy" to include 81 client-owned cats that had undergone bilateral thyroidectomy. METHODS Retrospective cross-sectional study assessing thyroid hormone concentrations of 68 cats within 6 months of surgery. A longitudinal study of thyroid status in 23 cats with >18 months follow-up post-thyroidectomy. A generalized estimating equation assessed the associations of bodyweight, tT4 and creatinine concentrations on SDMA concentration. RESULTS Sixty-eight cats had follow-up within 6 months. Fifteen cats (22%) had persistent, or recurrent, hyperthyroidism and 33 cats (49%) were hypothyroid. Twenty-three of the euthyroid/hypothyroid cats had long-term follow-up (595-1955 days); 4 cats (17%) remained hypothyroid, 19 cats (83%) were euthyroid (often transiently), and 9 of 23 cats (44%) developed recurrent hyperthyroidism. Symmetric dimethylarginine and creatinine were linearly associated, but hyperthyroid cats had higher SDMA concentrations, relative to creatinine (P = .003). CONCLUSIONS AND CLINICAL IMPORTANCE Cats have changes in thyroid function for years after bilateral thyroidectomy, with a high incidence of recurrent hyperthyroidism. Both SDMA and creatinine are affected by thyroxine concentrations, and the effect is greater in hyperthyroid cats.
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Affiliation(s)
- Heather L Covey
- Department of Clinical Science and Services, Small Animal Medicine and Surgery Group, The Royal Veterinary College, Hertfordshire, United Kingdom
| | - Yu-Mei Chang
- Research Support Office, The Royal Veterinary College, London, United Kingdom
| | - Jonathan Elliott
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, London, United Kingdom
| | - Harriet M Syme
- Department of Clinical Science and Services, Small Animal Medicine and Surgery Group, The Royal Veterinary College, Hertfordshire, United Kingdom
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17
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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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18
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Stock E, Daminet S, Paepe D, Buresova E, Vandermeulen E, Smets P, Duchateau L, Saunders JH, Vanderperren K. Evaluation of Renal Perfusion in Hyperthyroid Cats before and after Radioiodine Treatment. J Vet Intern Med 2017; 31:1658-1663. [PMID: 29031027 PMCID: PMC5697172 DOI: 10.1111/jvim.14852] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 08/05/2017] [Accepted: 09/13/2017] [Indexed: 12/28/2022] Open
Abstract
Background Hyperthyroidism and chronic kidney disease (CKD) are common in elderly cats. Consequently, both diseases often occur concurrently. Furthermore, renal function is affected by thyroid status. Because changes in renal perfusion play an important role in functional renal changes in hyperthyroid cats, investigation of renal perfusion may provide novel insights. Objectives To evaluate renal perfusion in hyperthyroid cats with contrast‐enhanced ultrasound (CEUS). Animals A total of 42 hyperthyroid cats was included and evaluated before and 1 month after radioiodine treatment. Methods Prospective intrasubject clinical trial of contrast‐enhanced ultrasound using a commercial contrast agent (SonoVue) to evaluate renal perfusion. Time‐intensity curves were created, and perfusion parameters were calculated by off‐line software. A linear mixed model was used to examine differences between pre‐ and post‐treatment perfusion parameters. Results An increase in several time‐related perfusion parameters was observed after radioiodine treatment, indicating a decreased blood velocity upon resolution of the hyperthyroid state. Furthermore, a small post‐treatment decrease in peak enhancement was present in the renal medulla, suggesting a lower medullary blood volume. Conclusions and Clinical Importance Contrast‐enhanced ultrasound indicated a higher cortical and medullary blood velocity and higher medullary blood volume in hyperthyroid cats before radioactive treatment in comparison with 1‐month post‐treatment control.
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Affiliation(s)
- E Stock
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - S Daminet
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - D Paepe
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - E Buresova
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - E Vandermeulen
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - P Smets
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - L Duchateau
- Department of Comparative Physiology and Biometry (Duchateau), Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - J H Saunders
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - K Vanderperren
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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19
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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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20
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Lucy JM, Peterson ME, Randolph JF, Scrivani PV, Rishniw M, Davignon DL, Thompson MS, Scarlett JM. Efficacy of Low-dose (2 millicurie) versus Standard-dose (4 millicurie) Radioiodine Treatment for Cats with Mild-to-Moderate Hyperthyroidism. J Vet Intern Med 2017; 31:326-334. [PMID: 28158908 PMCID: PMC5354058 DOI: 10.1111/jvim.14646] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 09/18/2016] [Accepted: 11/29/2016] [Indexed: 12/02/2022] Open
Abstract
Background Radioiodine (131I) is effective treatment for hyperthyroidism in cats, but optimal dose to restore euthyroidism without inducing hypothyroidism is unclear. Treatment‐induced hypothyroidism can lead to azotemia and reduced duration of survival. Objective To compare efficacy and short‐term outcomes of low‐dose 131I versus higher, standard‐dose 131I as treatment for hyperthyroidism. Animals A total of 189 client‐owned cats undergoing 131I treatment for mild‐to‐moderate hyperthyroidism (serum T4 ≥ 4.0 μg/dL and <13.0 μg/dL). Methods Prospective, nonrandomized, cohort study comparing treatment with either low‐dose (2 mCi, n = 150) or standard‐dose (4 mCi, n = 39) 131I. Serum T4, thyroid‐stimulating hormone (TSH), and creatinine concentrations were measured after 1, 3, and 6 months to determine persistent hyperthyroidism, overt hypothyroidism (low T4, high TSH), subclinical hypothyroidism (normal T4, high TSH), and azotemia. Results There was no significant difference in prevalence of cats with persistent hyperthyroidism between standard‐ and low‐dose treatment groups at 3 (0% versus 5.3%; P = .34) and 6 (0% versus 3.3%; P = .51) months. Overt (18% versus 1%; P = .0005) or subclinical (46% versus 21%; P = .004) hypothyroidism was more common in cats at 6 months after standard‐dose 131I. No difference in incidence of azotemia existed between groups, but cats treated with standard‐dose 131I had higher creatinine concentrations (P < .05) and higher percent rises in creatinine (P < .0001). Conclusions and Clinical Importance Low‐dose 131I is safe and effective for cats with mild‐to‐moderate hyperthyroidism, as evidenced by a cure rate of >95% with reduced frequency of iatrogenic hypothyroidism and azotemia.
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Affiliation(s)
- J M Lucy
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | | | - J F Randolph
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - P V Scrivani
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - M Rishniw
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - D L Davignon
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - M S Thompson
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - J M Scarlett
- Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
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21
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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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