TSH Explained: The Test Behind Most Thyroid Diagnoses
Here’s something that surprises a lot of people: TSH, the test most commonly used to check the thyroid, isn’t actually made by the thyroid. It’s made by the pituitary gland, in the brain, and it works like a messenger telling the thyroid how much hormone to produce.
When TSH is high, it usually means the pituitary is “shouting” at an underactive thyroid to work harder. When it’s low, the thyroid may be overactive and the brain is telling it to slow down. That’s why TSH is the standard first test for thyroid problems, even though it’s testing the messenger and not the thyroid directly.
Why people check their TSH
- Fatigue, weight changes, or mood changes without an obvious cause
- Monitoring an existing thyroid medication
- A family history of thyroid disease
What to expect
No fasting needed. If you take biotin, let your doctor know, since it can skew thyroid test results.
Ready to order? The TSH (Thyroid Stimulating Hormone) is $34 at SelectATest, with results in your own secure online portal.
This post is for general information and does not replace advice from your own doctor. Tests are ordered by an independent licensed physician, and results are not a diagnosis. If you are having a medical emergency, call 911.