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Changes in the size of the thyroid in patients with benign non-toxic multinodular goiter after radioactive iodine therapy. Med J Islam Repub Iran 2019; 32:131. [PMID: 30815426 PMCID: PMC6387795 DOI: 10.14196/mjiri.32.131] [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: 09/02/2017] [Indexed: 12/01/2022] Open
Abstract
Background: Multinodular goiter (MNG) is regarded as one of the most common causes of hyperthyroidism, particularly in areas of mild-to-moderate iodine deficiency. The present study aims to explore the effects of the radioactive iodine (RAI) therapy on benign non-toxic MNG and evaluate its side effects.
Methods: Patients with benign non-toxic MNG entered the study. Ultrasonography was applied to calculate the percentage of the decrease in the size of the thyroid before and six months minimum after the treatment. Chi-square, Mann-Whiteny-U and T-test were done using SPSS v.18.0 (p<0.05).
Results: The volumes of the thyroid lobes and nodules decreased significantly due to RAI therapy (p<0.001). The total volume of the thyroid, volume of the right nodule, and volume of the left nodule decreased by 77.8%, 40.7%, and 34.6% respectively.
Conclusion: According to the results of the current study, RAI therapy is an effective treatment method although it has short-term side effects. This treatment option is recommended for patients with benign non-toxic MNG, notably those who cannot be a candidate for surgery. This treatment affects the size of the thyroid and its nodules significantly and decreases almost all of the complications.
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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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Fast S, Hegedüs L, Pacini F, Pinchera A, Leung AM, Vaisman M, Reiners C, Wemeau JL, Huysmans DA, Harper W, Rachinsky I, de Souza HN, Castagna MG, Antonangeli L, Braverman LE, Corbo R, Düren C, Proust-Lemoine E, Marriott C, Driedger A, Grupe P, Watt T, Magner J, Purvis A, Graf H. Long-term efficacy of modified-release recombinant human thyrotropin augmented radioiodine therapy for benign multinodular goiter: results from a multicenter, international, randomized, placebo-controlled, dose-selection study. Thyroid 2014; 24:727-35. [PMID: 24341527 PMCID: PMC3993022 DOI: 10.1089/thy.2013.0370] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Enhanced reduction of multinodular goiter (MNG) can be achieved by stimulation with recombinant human thyrotropin (rhTSH) before radioiodine ((131)I) therapy. The objective was to compare the long-term efficacy and safety of two low doses of modified release rhTSH (MRrhTSH) in combination with (131)I therapy. METHODS In this phase II, single-blinded, placebo-controlled study, 95 patients (57.2 ± 9.6 years old, 85% women, 83% Caucasians) with MNG (median size 96.0 mL; range 31.9-242.2 mL) were randomized to receive placebo (n=32), 0.01 mg MRrhTSH (n=30), or 0.03 mg MRrhTSH (n=33) 24 hours before a calculated (131)I activity. Thyroid volume (TV) and smallest cross-sectional area of trachea (SCAT) were measured (by computed tomography scan) at baseline, six months, and 36 months. Thyroid function and quality of life (QoL) was evaluated at three-month and yearly intervals respectively. RESULTS At six months, TV reduction was enhanced in the 0.03 mg MRrhTSH group (32.9% vs. 23.1% in the placebo group; p=0.03) but not in the 0.01 mg MRrhTSH group. At 36 months, the mean percent TV reduction from baseline was 44 ± 12.7% (SD) in the placebo group, 41 ± 21.0% in the 0.01 mg MRrhTSH group, and 53 ± 18.6% in the 0.03 mg MRrhTSH group, with no statistically significant differences among the groups, p=0.105. In the 0.03 mg MRrhTSH group, the subset of patients with basal (131)I uptake <20% had a 24% greater TV reduction at 36 months than the corresponding subset of patients in the placebo group (p=0.01). At 36 months, the largest relative increase in SCAT was observed in the 0.03 mg MRrhTSH group (13.4 ± 23.2%), but this was not statistically different from the increases observed in the placebo or the 0.01 mg MRrhTSH group (p=0.15). Goiter-related symptoms were reduced and QoL improved, without any enhanced benefit from using MRrhTSH. At three years, the prevalence of permanent hypothyroidism was 13%, 33%, and 45% in the placebo, 0.01 mg, and 0.03 mg MRrhTSH groups respectively. The overall safety profile of the study was favorable. CONCLUSIONS When used as adjuvant to (131)I, enhanced MNG reduction could not be demonstrated with MRrhTSH doses ≤ 0.03 mg, indicating that the lower threshold for efficacy is around this level.
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Affiliation(s)
- Søren Fast
- Department of Endocrinology and Metabolism, Odense University Hospital, Odense, Denmark
| | - Laszlo Hegedüs
- Department of Endocrinology and Metabolism, Odense University Hospital, Odense, Denmark
| | - Furio Pacini
- Section of Endocrinology and Metabolism, University of Siena, Siena, Italy
| | - Aldo Pinchera
- WHO Collaborating Center for the Diagnosis and Treatment of Thyroid Cancer and Other Thyroid Diseases, Department of Endocrinology, University Hospital of Pisa, Pisa, Italy
| | - Angela M. Leung
- Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, Massachusetts
| | - Mario Vaisman
- Department of Internal Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Christoph Reiners
- Department of Nuclear Medicine, University of Wuerzburg, Wuerzburg, Germany
| | - Jean-Louis Wemeau
- Department of Endocrinology, Clinique Marc Linquette, Hôpital Huriez, CHRU Lille, Lille, France
| | - Dyde A. Huysmans
- Department of Nuclear Medicine, Catharina Hospital, Eindhoven, The Netherlands
| | - William Harper
- Department of Internal Medicine, Hamilton General Hospital, Hamilton, Canada
| | - Irina Rachinsky
- Nuclear Medicine Department, London Health Sciences Center, London, Canada
| | - Hevelyn Noemberg de Souza
- Service of Endocrinology and Metabolism (SEMPR), Clinics Hospital of the Federal University of Paraná, Curitiba, Brazil
| | - Maria G. Castagna
- Section of Endocrinology and Metabolism, University of Siena, Siena, Italy
| | - Lucia Antonangeli
- WHO Collaborating Center for the Diagnosis and Treatment of Thyroid Cancer and Other Thyroid Diseases, Department of Endocrinology, University Hospital of Pisa, Pisa, Italy
| | - Lewis E. Braverman
- Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, Massachusetts
| | - Rossana Corbo
- Department of Internal Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Christian Düren
- Department of Nuclear Medicine, University of Wuerzburg, Wuerzburg, Germany
| | | | | | - Albert Driedger
- Nuclear Medicine Department, London Health Sciences Center, London, Canada
| | - Peter Grupe
- Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark
| | - Torquil Watt
- Department of Endocrinology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - James Magner
- Department of Endocrinology, Genzyme, (a Sanofi Company), Cambridge, Massachusetts
| | - Annie Purvis
- Department of Biostatistics, Genzyme, (a Sanofi Company), Cambridge, Massachusetts
| | - Hans Graf
- Service of Endocrinology and Metabolism (SEMPR), Clinics Hospital of the Federal University of Paraná, Curitiba, Brazil
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Campos M, Peremans K, Vandermeulen E, Duchateau L, Bosmans T, Polis I, Daminet S. Effect of recombinant human thyrotropin on the uptake of radioactive iodine (¹²³I) in dogs with thyroid tumors. PLoS One 2012; 7:e50344. [PMID: 23209716 PMCID: PMC3510219 DOI: 10.1371/journal.pone.0050344] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 10/18/2012] [Indexed: 11/18/2022] Open
Abstract
In humans, recombinant human thyrotropin (rhTSH) enhances radioactive iodine uptake (RAIU) in patients with differentiated thyroid cancer. No studies have been performed in veterinary medicine to optimize radioiodine treatment of thyroid cancer. The aim of this study was to evaluate the effect of rhTSH on the uptake of radioiodine-123 ((123)I) in dogs with thyroid tumors. Nine dogs with thyroid neoplasia were included in this prospective cross-over study. The dogs were divided in 2 groups. In one group, (123)I was administered for a baseline RAIU determination in week 1. In week 2 (after a washout period of 2 weeks), these dogs received rhTSH (100 μg IV) 24 h before (123)I injection. In the other group the order of the protocol was reversed. For each scan, the dogs received 37 MBq (1 mCi) of (123)I intravenously (IV) and planar scintigraphy was performed after 8 and 24 h for tumor RAIU calculation. Overall, rhTSH administration caused no statistically significant change on thyroid tumor RAIU at 8 h (p = 0.89) or at 24 h (p = 0.98). A significant positive correlation was found between the effect of rhTSH on tumor 8h-RAIU and rhTSH serum concentrations at 6 h (τ = 0.68; p = 0.03), at 12 h (τ = 0.68; p = 0.03) and at 24 h (τ = 0.78; p = 0.02) after rhTSH injection. This study suggests that IV administration of 100 μg rhTSH 24 h before (123)I has an inconsistent effect on thyroid tumor RAIU. Further studies are necessary to determine the best protocol of rhTSH administration to optimize thyroid tumor RAIU.
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Affiliation(s)
- Miguel Campos
- Department of Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
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Laplano NER, Mercado-Asis LB. Recombinant TSH and Lithium Overcomes Amiodarone-Induced Low Radioiodine Uptake in a Thyrotoxic Female. Int J Endocrinol Metab 2012; 10:625-8. [PMID: 23843834 PMCID: PMC3693641 DOI: 10.5812/ijem.5406] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 05/20/2012] [Accepted: 05/25/2012] [Indexed: 11/16/2022] Open
Abstract
INTRODUCTION Recombinant human thyroid-stimulating hormone(rhTSH) increases radioactive iodine uptake(RAIU) in selected populations, while lithium is used as an adjunct to radioactive iodine (RAI) therapy in Graves' disease with low RAIU. In this report, both drugs used in combination, overcame low iodine-131 uptake in a Graves' patient. CLINICAL CASE A 39-year old female with Graves' disease, acquired thionamide-induced agranulocytosis, and severe hypokalemia, subsequently went into cardiorespiratory arrest. On resuscitation, she had ventricular tachyarrhythmias which were cardioverted using amiodarone. She was subsequently placed on IV hydrocortisone amiodarone and propranolol. On admission, she was normotensive, tachycardic, and afebrile. She had fine tremors, hyper reflexia, and diffuse, non-tender thyromegaly. Initial investigations showed normal complete blood count, hypokalemia and elevated alanine transaminase levels. Levels of thyroid stimulating hormone were low (0.03 uIU/L, N = 0.27-3.75). Thyroid ultrasound showed diffuse thyromegaly with uniform echopattern and normal color flow Doppler, radioiodine uptake showed low uptake at 0400h and 2400h (6% and 7%, respectively). In preparation for RAI therapy, she was given lithium 900mg/day for 12 days to increase RAI retention. To increase iodine-131 uptake, two doses of 0.9mg rhTSH were injected intramuscular, 24 hours apart, before RAI therapy. Repeat RAIU after the second dose of rhTSH showed more than a 5-fold increase in 0400h uptake compared with the baseline (32% vs. 6%). Exactly 24 hours after the second dose of rhTSH, she was given 25mCi of iodine-131. Thereafter, the patient's clinical and biochemical markers continued to improve. She became hypothyroid and is currently on levothyroxine replacement therapy. CONCLUSIONS This case demonstrates the efficacy of combining rhTSH and lithium to overcome amiodarone-induced low iodine-131 uptake in Graves' disease.
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Affiliation(s)
- Nestor Eric R. Laplano
- Section of Endocrinology and Metabolism, University of Santo Tomas Hospital, Manila, Philippines
- Corresponding author: Nestor Eric R. Laplano, St. Thomas Diabetes Center, 2nd Floor, University of Santo Tomas Hospital, Espana, Manila, Philippines. Tel/Fax: +632-7313001, E-mail:
| | - Leilani B. Mercado-Asis
- Section of Endocrinology and Metabolism, University of Santo Tomas Hospital, Manila, Philippines
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Zafon C, Rodríguez B, Montoro JB, Cabo D, Mesa J. Inability of recombinant human thyrotropin to predict the evolution from subclinical hypothyroidism to overt disease. A pilot study. J Endocrinol Invest 2012; 35:25-7. [PMID: 21521938 DOI: 10.3275/7684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND The use of recombinant human TSH (rhTSH) is indicated to evaluate thyroid carcinoma patients. In recent years, some authors have reported that rhTSH could serve as a dynamic test of thyroid reserve. The aim of the present study was to determine whether or not rhTSH can predict the evolution from subclinical hypothyroidism (SH) to overt hypothyroidism. MATERIALS AND METHODS Twenty-one women who met the diagnostic criteria of SH were enrolled. All patients received a single dose of rhTSH (0.1 mg). Basal blood samples for TSH, free T4 (fT4), thyroglobulin (Tg), and anti-thyoperoxidase and anti-Tg antibodies were obtained before and 1 day after rhTSH administration. All patients were followed for 2 yr, and blood samples were obtained every 6 months. RESULTS Twenty-four hours after rhTSH administration, the TSH level increased to >20 mU/l in 14 patients; the serum peak TSH levels remained <10 mU/l in only 5 patients. On follow-up, 7 women (33%) required L-T4 replacement therapy for overt hypothyroidism or a persistent TSH level >10 mlU/l. None of the parameters analyzed differed significantly between patients who developed overt hypothyroidism from those who had persistent SH. CONCLUSIONS The response of thyroid function tests to a single low dose of rhTSH is not useful in identifying those patients with SH who will develop overt hypothyroidism over a 2-yr period.
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Affiliation(s)
- C Zafon
- Department of Endocrinology, Hospital General Universitari Vall d'Hebron, Barcelona, Spain.
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Giusti M, Caputo M, Calamia I, Bagnara M, Ceresola E, Schiavo M, Mussap M, Ferone D, Minuto F, Bagnasco M. Long-term outcome of low-activity radioiodine administration preceded by adjuvant recombinant human TSH pretreatment in elderly subjects with multinodular goiter. Thyroid Res 2009; 2:6. [PMID: 19566933 PMCID: PMC2713215 DOI: 10.1186/1756-6614-2-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 06/30/2009] [Indexed: 11/13/2022] Open
Abstract
Background Large multinodular goiter (MNG) in elderly people is a common finding which can require intervention. The long-term effect of radioiodine therapy on thyroid volume (TV) and function after recombinant human (rh) TSH pre-treatment was evaluated. Methods After baseline evaluation, 40 subjects over 60 years old with a large MNG were treated with 131I up to the activity of 600 MBq. Nineteen patients were pretreated with rhTSH (0.1 mg on 2 consecutive days; group 1) while 21 subjects underwent treatment without rhTSH pretreatment (group 2). TV was monitored every 6–12 months by ultrasonography. The median follow-up period was 36 months. Results At the baseline, the groups matched in terms of TV, 24-h radioiodine uptake (RAIU), urinary iodine and neck complaints. The number of subjects pretreated with anti-thyroid drugs was significantly (P = 0.01) greater in group 2 than in group 1; TSH was more suppressed (P = 0.003) and f-T3 was more elevated (P = 0.005) in group 2 than in group 1 patients. RhTSH increased 24-h RAIU in group 1 up to the baseline level observed in group 2. The 131I activity administered was similar in both groups. Adverse events were slight and similar in both groups. A permanent post-radioiodine toxic condition was reported only in 2 patients in group 2. After radioiodine therapy, hypothyroidism was observed in significantly more group 1 patients than group 2 patients (P = 0.002). While TV was reduced in both groups, the percentage TV reduction recorded at the last examination was significantly higher (P = 0.03) in group 1 than in group 2. MNG-related complaints were significantly reduced in both group 1 (P = 0.0001 vs baseline) and group 2 (P = 0.001) patients. Conclusion Low radioiodine activities after pretreatment with low-dosage rhTSH are able to reduce TV and improve MNG-related symptoms in elderly subjects.
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Affiliation(s)
- Massimo Giusti
- Clinica Endocrinologica, Azienda Ospedaliera Universitaria "San Martino", Genoa, Italy.
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Eisenberg M, Samuels M, DiStefano JJ. Extensions, validation, and clinical applications of a feedback control system simulator of the hypothalamo-pituitary-thyroid axis. Thyroid 2008; 18:1071-85. [PMID: 18844475 PMCID: PMC2962855 DOI: 10.1089/thy.2007.0388] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND We upgraded our recent feedback control system (FBCS) simulation model of human thyroid hormone (TH) regulation to include explicit representation of hypothalamic and pituitary dynamics, and updated TH distribution and elimination (D&E) parameters. This new model greatly expands the range of clinical and basic science scenarios explorable by computer simulation. METHODS We quantified the model from pharmacokinetic (PK) and physiological human data and validated it comparatively against several independent clinical data sets. We then explored three contemporary clinical issues with the new model: combined triiodothyronine (T(3))/thyroxine (T(4)) versus T(4)-only treatment, parenteral levothyroxine (L-T(4)) administration, and central hypothyroidism. RESULTS Combined T(3)/T(4) therapy--In thyroidectomized patients, the L-T(4)-only replacement doses needed to normalize plasma T(3) or average tissue T(3) were 145 microg L-T(4)/day or 165 microg L-T(4)/day, respectively. The combined T(4) + T(3) dosing needed to normalize both plasma and tissue T(3) levels was 105 microg L-T(4) + 9 microg T(3) per day. For all three regimens, simulated mean steady-state plasma thyroid-stimulating hormone (TSH), T(3), and T(4) was within normal ranges (TSH: 0.5-5 mU/L; T(4): 5-12 microg/dL; T(3): 0.8-1.9 ng/mL). Parenteral T(4) administration--800 microg weekly or 400 microg twice weekly normalized average tissue T(3) levels both for subcutaneous (SC) and intramuscular (IM) routes of administration. TSH, T(3), and T(4) levels were maintained within normal ranges for all four of these dosing schemes (1x vs. 2x weekly, SC vs. IM). Central hypothyroidism--We simulated steady-state plasma T(3), T(4), and TSH concentrations in response to varying degrees of central hypothyroidism, reducing TSH secretion from 50% down to 0.1% of normal. Surprisingly, TSH, T(3), and T(4) plasma concentrations remained within normal ranges for TSH secretion as low as 25% of normal. CONCLUSIONS Combined T(3)/T(4) treatment--Simulated standard L-T(4)-only therapy was sufficient to renormalize average tissue T(3) levels and maintain normal TSH, T(3), and T(4) plasma levels, supporting adequacy of standard L-T(4)-only treatment. Parenteral T(4) administration-TSH, T(3), and T(4) levels were maintained within normal ranges for all four of these dosing schemes (1x vs. 2x weekly, SC vs. IM), supporting these therapeutic alternatives for patients with compromised L-T(4) gut absorption. Central hypothyroidism--These results highlight how highly nonlinear feedback in the hypothalamic-pituitary-thyroid axis acts to maintain normal hormone levels, even with severely reduced TSH secretion.
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Affiliation(s)
- Marisa Eisenberg
- Biocybernetics Laboratory, Departments of Computer Science, Medicine, and Biomedical Engineering, UCLA, Los Angeles, California 90095-1596, USA.
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