Hypothyroidism
Diagnose on TSH and free T4, treat overt disease with levothyroxine, think twice before treating subclinical disease in older people, and never miss central hypothyroidism or myxoedema coma.
Tier 1Condition
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Overt primary hypothyroidism (raised TSH, low free T4) was found on testing in 0.3% of the US population and subclinical hypothyroidism in 4.3% (NHANES III, Hollowell 2002), with more people already on levothyroxine. Both are far commoner in women and older people. Hashimoto thyroiditis is the usual cause in iodine-sufficient countries such as Australia.
- TSH is the screening test. It fails in central hypothyroidism, in acute illness and in the first months after treating hyperthyroidism.
- Levothyroxine at full dose for most adults; start low in older people and in coronary disease. Recheck TSH at 6 to 8 weeks.
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Sources
- Guidelines for the treatment of hypothyroidism, prepared by the American Thyroid Association Task Force on Thyroid Hormone ReplacementAmerican Thyroid Association (Jonklaas et al., Thyroid 2014;24:1670-751), 2014 (current ATA hypothyroidism guideline, checked against the ATA guideline list November 2026)
- 2013 ETA guideline on the management of subclinical hypothyroidismEuropean Thyroid Association (Pearce et al., Eur Thyroid J 2013;2:215-28), 2013
- Thyroid hormone therapy for older adults with subclinical hypothyroidism (TRUST)Stott DJ et al., N Engl J Med 2017;376:2534-44, 2017
- American Thyroid Association 2026 guidelines for thyroid disease in preconception, pregnancy, and postpartumAmerican Thyroid Association (Korevaar, Leung, Alexander et al., Thyroid 2026;36(5):481-544), 2026 (replaces the 2017 ATA pregnancy guideline; full text paywalled, key recommendations read via the 2026 editorial summary below, November 2026)
- Navigating the RCOG 2025 and ATA 2026 guideline updates on the management of thyroid disorders during pregnancyAthanasiadou KI, Peppa M, Kalantaridou SN, Paschou SA. Case Rep Womens Health 2026, 2026 (editorial)
- Serum TSH, T4, and thyroid antibodies in the United States population (1988 to 1994): NHANES III (Hollowell JG et al. J Clin Endocrinol Metab 2002;87(2):489-99)Journal of Clinical Endocrinology and Metabolism, 2002
- Endocrinology (Therapeutic Guidelines)AU/NZTherapeutic Guidelines Ltd
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Deploy to Cloudflare on push to main