TSH (Thyroid)
Also known as: Thyroid test, Thyroid hormone test, thyroid ka test, TSH test kya hai
Thyroid-stimulating hormone, made by the pituitary gland to tell the thyroid how hard to work. It is the best first test of thyroid function.
Why it's ordered
Investigating tiredness, weight change, feeling cold or hot, palpitations, irregular periods, and monitoring thyroid medicine.
Preparation
No fasting needed. If you take levothyroxine, many labs prefer you test before your daily dose. Stop biotin supplements 2–3 days before (they can distort the result).
Typical adult values
| Typical adult range | about 0.4–4.0 mIU/L (varies by lab) |
|---|
Ranges vary between labs and methods. Always use the range printed on your report.
If it's high
High TSH usually means an underactive thyroid (hypothyroidism), or too low a dose of thyroid medicine.
If it's low
Low TSH usually means an overactive thyroid (hyperthyroidism), or too high a dose of thyroid medicine.
Good to know
A single slightly abnormal TSH is often repeated after 6–8 weeks, with Free T4, before starting treatment. Pregnancy uses different ranges.
Common questions
Do I need to fast for a TSH test?
No fasting needed. If you take levothyroxine, many labs prefer you test before your daily dose.
Is a TSH of 6 high?
Yes, 6 is above the typical adult range of about 0.4–4.0 mIU/L. A single slightly high TSH is often repeated after 6–8 weeks, with Free T4, before starting treatment. Always use the range printed on your report.
What does a low TSH mean?
Low TSH usually means an overactive thyroid (hyperthyroidism), or too high a dose of thyroid medicine.
Should I stop biotin before a thyroid test?
Stop biotin supplements 2–3 days before, because they can distort the result.