My TSH is low — what should I do?
Low TSH suggests hyperthyroidism (primary) or central hypothyroidism (rare). Confirm with free T4, free T3, and TPO/TRAb antibodies. Symptomatic or biochemically overt cases are referred to endocrinology.
Full answer
A low TSH is most commonly primary hyperthyroidism; less commonly central hypothyroidism or transient suppression from illness, medications, or supplements (biotin assay interference). Confirmation includes free T4, free T3, TPO antibodies, and TRAb when Graves' is suspected. Symptomatic or overt cases — palpitations, weight loss, tremor, suppressed TSH with elevated free T4/T3 — are referred to endocrinology. Subclinical findings are tracked. Hormone optimization is held or adjusted until the thyroid axis is characterized because SHBG, lipids, and heart rate are confounded.
Educational. Not a substitute for individualized provider review.
- Methodology — Primary source · oMeds
- Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-06-03