ThyroidReported in mIU/LThyroid-stimulating hormone (TSH)
The pituitary hormone that tells the thyroid to make T4 and T3. It is the most sensitive single thyroid screening test.
What it measures
The pituitary gland releases TSH in response to how much thyroid hormone it senses. When hormone is scarce, TSH rises to push the gland. When hormone is abundant, TSH falls. That feedback loop is why a small change in thyroid output produces a large change in TSH. The adult interval on this panel is wider than some labs use. Methods and cutoffs differ slightly.
Why it is on the panel
TSH is the right first number for “is the thyroid keeping up?” Fatigue, weight change, hair and skin changes, constipation, palpitations, and cholesterol shifts are all reasons people look here. On a preventive panel it finds quiet thyroid disease before it is obvious.
How to read it
A high TSH means the pituitary is asking for more hormone. Check free T4 to see whether the gland is meeting that request. A low TSH means the pituitary is being told to stop. Check free T4 and total T3 to see whether hormone is actually high. Pregnancy, serious illness, and pituitary disease break these simple rules.
When it runs higher
Hypothyroidism is the classic cause, including Hashimoto’s disease. Recovery from illness, some medicines, and under-replaced thyroid hormone also raise TSH. A mildly high TSH with a normal free T4 is common and is not automatically treated.
When it runs lower
Hyperthyroidism, thyroiditis, excess thyroid medication, and early pregnancy can suppress TSH. A very low TSH with high free T4 or T3 is an overactive pattern. A low TSH with low free T4 points away from the thyroid gland and toward the pituitary, which is a different evaluation.
Same group
Other Thyroid tests
How to use this page
This page explains what the measurement is for. It is educational. Your Healiam report includes the reference interval for your age and sex, and a clinician reads that result with your history, medicines, and the rest of the panel. Talk with a clinician before changing diet, supplements, or treatment because of a number on a report.
TSH
TSH is part of the full panel.
No referral or insurance required.
One preventive draw covers this measurement and the rest of the Healiam panel. CLIA-certified results come back in days.