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Thyroid testing in primary hypothyroidism

Therapeutics Initiative (University of British Columbia)

Background: Thyroid hormones regulate essential metabolic processes and development. The hypothalamicpituitary-thyroid axis regulates hormone production, with thyroid stimulating hormone (TSH) levels being a key indicator of thyroid function in primary hypothyroidism. Aims: This Therapeutics Letter emphasizes a TSH-centred approach to the diagnosis and management of primary hypothyroidism (dysfunction at the level of the thyroid gland) in adults. It discourages routine thyroid function screening in asymptomatic individuals due to lack of demonstrated benefit and potential harm from overdiagnosis and overtreatment. It outlines appropriate diagnostic strategies, including when to use TSH, free T4 (thyroxine), and free T3 (triiodothyronine) tests, and outlines indications for antibody testing. Special considerations are provided for subclinical hypothyroidism and hypothyroidism during pregnancy. Recommendations: ▪ Do not perform routine thyroid function screening in asymptomatic adults. ▪ Use TSH as the initial test for suspected primary thyroid dysfunction and as the test to monitor levothyroxine monotherapy for primary hypothyroidism. ▪ Wait six weeks before re-checking TSH after therapy adjustments; once stable, annual testing is sufficient. ▪ Avoid treating asymptomatic screen-detected subclinical hypothyroidism, except when TSH >10 mU/L in patients under 70 years of age. ▪ In pregnancy, test TSH only in high-risk women; treat overt hypothyroidism, but avoid routine treatment of subclinical cases.

Other

eng

2025-05-07

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/91032

Reviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/