Thyroid hormone dose adjustments based on thyroid function tests

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In print

Pharmacotherapy

Thyroid hormone dose adjustments based on thyroid function tests

11 October 2023

By Hilary Krebs

Wednesday 11 October 2023, 12:35 AM

T4 can be thought of as coffee beans, which are converted/ground to T3 as needed [Image: Ashkan Forouzani on Unsplash]

This article discusses the pitfalls in interpreting thyroid function tests when used to guide dose adjustments for thyroid hormone replacement

Key points, Thyroid-stimulating hormone levels alone should be used to guide levothyroxine dosing in almost all cases. Small adjustments in levothyroxine can ha, Pract Green w Pale Yellow

Investigations

References

Bornschein A, Paz-Filho G, Graf H, Carvalho GA. Treating primary hypothyroidism with weekly doses of levothyroxine: a randomized, single-blind, crossover study. Arq Bras Endocrinol Metabol 2012;56(4):250–58.
Duntas LH, Jonklaas J. Levothyroxine dose adjustment to optimise therapy throughout a patient’s lifetime. Adv Ther 2019;36(Suppl 2):30–46.
Dutta D, Jindal R, Kumar M, et al. Efficacy and safety of once weekly thyroxine as compared to daily thyroxine in managing primary hypothyroidism: A systematic review and meta-analysis. Indian J Endocrinol Metab 2021;25(2):76–85.
Jayakumari C, Nair A, Puthiyaveettil Khadar J, et al. Efficacy and safety of once-weekly thyroxine for thyroxine-resistant hypothyroidism. J Endocr Soc 2019;3(12):2184–93.
Jonklaas J, Bianco AC, Bauer AJ, et al. Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement. Thyroid 2014;24(12):1670–751.
Koulouri O, Moran C, Halsall D, et al. Pitfalls in the measurement and interpretation of thyroid function tests. Best Pract Res Clin Endocrinol Metab 2013;27(6):745–62.
Ramadhan A, Tamilia M. Treatment-refractory hypothyroidism. CMAJ 2012;184(2):205–09.
The Royal College of Pathologists of Australasia. Position Statement: Thyroid Function Testing for Adult Diagnosis and Monitoring. 2017. https://www.rcpa.edu.au/Library/College-Policies/Position-Statements/Thyroid-Function-Testing-for-Adult-Diagnosis-and-M
Waring AC, Arnold AM, Newman AB, et al. Longitudinal changes in thyroid function in the oldest old and survival: the cardiovascular health study all-stars study. J Clin Endocrinol Metab 2012;97(11):3944–50.

How to Treat

+How to treat

For older people and frail people, the long-term benefit of medicines reduces and the potential for harm from adverse effects increases. When the benefit–risk balance changes in this way, medicine review and optimisation are important to simplify the therapeutic regimen, reduce inappropriate medicines and minimise risks. In this article, pharmacist prescriber Linda Bryant uses two case studies to illustrate important considerations during medicine reviews

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