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Does One Size Fit Everyone? Replacement Dose of Levothyroxine in Long-standing Primary Hypothyroidism in Adults

OBJECTIVES: The recommended starting dose of levothyroxine (LT4) in primary hypothyroidism is 1.6 μg/kg body weight and is based on presumption of minimal residual thyroid function in autoimmune hypothyroidism. This study aimed at finding the range and determining factors for LT4 dose in long-standi...

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Autor principal: Singh, Rekha
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Medknow Publications & Media Pvt Ltd 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5434723/
https://www.ncbi.nlm.nih.gov/pubmed/28553595
http://dx.doi.org/10.4103/ijem.IJEM_502_16
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author Singh, Rekha
author_facet Singh, Rekha
author_sort Singh, Rekha
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description OBJECTIVES: The recommended starting dose of levothyroxine (LT4) in primary hypothyroidism is 1.6 μg/kg body weight and is based on presumption of minimal residual thyroid function in autoimmune hypothyroidism. This study aimed at finding the range and determining factors for LT4 dose in long-standing hypothyroidism. METHODS: A cross-sectional study of individuals with primary autoimmune hypothyroidism on LT4 replacement was done between March 2015 and January 2016. Individuals enrolled were euthyroid based on recent serum thyroid-stimulating hormone. The inclusion criteria included LT4 intake in the morning empty stomach, maintenance of at least 1-h food gap, not on medications known to hamper LT4 absorption within 4 h of dosing, diagnosis of hypothyroidism at least for 1 year, and on a minimum 25 μg LT4. P < 0.05 was considered statistically significant. RESULTS: A total of 346 individuals (290 women and 56 men; 214 premenopausal and 76 postmenopausal women) were enrolled. The mean duration of hypothyroidism and age were 5.7 years and 42.1 years, respectively. The range and mean of absolute LT4 daily dose (ADD), LT4 dose based on body weight (D/W), and LT4 dose based on ideal body weight (D/IBW) were 25–200 μg daily and 77.1 μg, 0.3–2.82 μg/kg and 1.21 μg/kg, and 0.42–3.5 μg/kg and 1.58 μg/kg, respectively. Duration of hypothyroidism was significant predictors of ADD, D/W, and D/IBW. Gender-based difference in ADD and D/IBW was explained by gender difference in anthropometry. CONCLUSION: Long-standing primary autoimmune hypothyroidism has variable dose requirement of LT4 for achieving euthyroidism and may be dependent on the degree of residual functional thyroid. Duration of hypothyroidism was significant positive predictor for either ADD, D/W, or D/IBW.
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spelling pubmed-54347232017-05-26 Does One Size Fit Everyone? Replacement Dose of Levothyroxine in Long-standing Primary Hypothyroidism in Adults Singh, Rekha Indian J Endocrinol Metab Original Article OBJECTIVES: The recommended starting dose of levothyroxine (LT4) in primary hypothyroidism is 1.6 μg/kg body weight and is based on presumption of minimal residual thyroid function in autoimmune hypothyroidism. This study aimed at finding the range and determining factors for LT4 dose in long-standing hypothyroidism. METHODS: A cross-sectional study of individuals with primary autoimmune hypothyroidism on LT4 replacement was done between March 2015 and January 2016. Individuals enrolled were euthyroid based on recent serum thyroid-stimulating hormone. The inclusion criteria included LT4 intake in the morning empty stomach, maintenance of at least 1-h food gap, not on medications known to hamper LT4 absorption within 4 h of dosing, diagnosis of hypothyroidism at least for 1 year, and on a minimum 25 μg LT4. P < 0.05 was considered statistically significant. RESULTS: A total of 346 individuals (290 women and 56 men; 214 premenopausal and 76 postmenopausal women) were enrolled. The mean duration of hypothyroidism and age were 5.7 years and 42.1 years, respectively. The range and mean of absolute LT4 daily dose (ADD), LT4 dose based on body weight (D/W), and LT4 dose based on ideal body weight (D/IBW) were 25–200 μg daily and 77.1 μg, 0.3–2.82 μg/kg and 1.21 μg/kg, and 0.42–3.5 μg/kg and 1.58 μg/kg, respectively. Duration of hypothyroidism was significant predictors of ADD, D/W, and D/IBW. Gender-based difference in ADD and D/IBW was explained by gender difference in anthropometry. CONCLUSION: Long-standing primary autoimmune hypothyroidism has variable dose requirement of LT4 for achieving euthyroidism and may be dependent on the degree of residual functional thyroid. Duration of hypothyroidism was significant positive predictor for either ADD, D/W, or D/IBW. Medknow Publications & Media Pvt Ltd 2017 /pmc/articles/PMC5434723/ /pubmed/28553595 http://dx.doi.org/10.4103/ijem.IJEM_502_16 Text en Copyright: © 2017 Indian Journal of Endocrinology and Metabolism http://creativecommons.org/licenses/by-nc-sa/3.0 This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
spellingShingle Original Article
Singh, Rekha
Does One Size Fit Everyone? Replacement Dose of Levothyroxine in Long-standing Primary Hypothyroidism in Adults
title Does One Size Fit Everyone? Replacement Dose of Levothyroxine in Long-standing Primary Hypothyroidism in Adults
title_full Does One Size Fit Everyone? Replacement Dose of Levothyroxine in Long-standing Primary Hypothyroidism in Adults
title_fullStr Does One Size Fit Everyone? Replacement Dose of Levothyroxine in Long-standing Primary Hypothyroidism in Adults
title_full_unstemmed Does One Size Fit Everyone? Replacement Dose of Levothyroxine in Long-standing Primary Hypothyroidism in Adults
title_short Does One Size Fit Everyone? Replacement Dose of Levothyroxine in Long-standing Primary Hypothyroidism in Adults
title_sort does one size fit everyone? replacement dose of levothyroxine in long-standing primary hypothyroidism in adults
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5434723/
https://www.ncbi.nlm.nih.gov/pubmed/28553595
http://dx.doi.org/10.4103/ijem.IJEM_502_16
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