lab metric
Thyroid-Stimulating Hormone (TSH)
Table of contents
Description
TSH (thyroid-stimulating hormone) is produced by the pituitary gland and acts as the body’s “thermostat signal” for thyroid function. When thyroid hormone levels are insufficient for the body’s needs, TSH typically rises to stimulate the thyroid to produce more hormone. When thyroid hormone is high (or the body is receiving too much replacement), TSH is usually suppressed.
Why it matters
TSH is often the most sensitive single screening marker for thyroid dysfunction. It’s commonly interpreted alongside Free T4 (and sometimes Free T3), plus symptoms and medication context.
What higher or lower results can suggest (general education)
High TSH: commonly suggests hypothyroidism (often autoimmune/Hashimoto’s), or under-replacement if on thyroid medication.
Low TSH: can suggest hyperthyroidism, thyroid hormone over-replacement, or certain pituitary patterns (less common).
Context that changes interpretation
Illness, pregnancy, and medications/supplements (including biotin) can shift results. A mildly abnormal value is often rechecked to confirm a stable pattern before conclusions are drawn.
Educational only, not medical advice. If TSH is abnormal or thyroid symptoms are present (palpitations, heat/cold intolerance, fatigue, weight change), review results with a clinician.
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