Thyroid test (TSH): what it shows and normal range
Medically reviewed by Dr. N. S. Santosh Varma, MBBS, FIM, FIDM, FICCM · Reg. APMC/FMR 112686 · Reviewed October 2026
A TSH test measures thyroid stimulating hormone, the signal your brain sends to the thyroid gland. A high TSH usually means the thyroid is underactive (hypothyroidism) and a low TSH usually means it is overactive (hyperthyroidism). Many labs use a reference range of roughly 0.4 to 4.0 mIU/L, but ranges differ between labs, and doctors often add T3 and T4 tests to confirm.
What the result usually means
| TSH result | What it often suggests |
|---|---|
| Within the lab's range | Thyroid function is likely normal |
| Above the range | Possible underactive thyroid; doctor may check free T4 |
| Below the range | Possible overactive thyroid; doctor may check free T3 and T4 |
Pregnancy, some medicines, recent illness and the time of day can affect TSH. Only a doctor should interpret it with your symptoms.
Symptoms that prompt a thyroid test
- Tiredness, weight gain, feeling cold, dry skin, constipation (underactive)
- Weight loss, palpitations, anxiety, heat intolerance, tremor (overactive)
- Irregular periods or difficulty conceiving
- Swelling in the front of the neck
- A family history of thyroid disease
Preparation
- Fasting is usually not required for TSH alone
- If you take thyroid medicine, ask your doctor whether to take it before or after the sample
- Tell the collector about biotin supplements, which can affect some thyroid tests
Is it included in YIRA's checkup?
This test is not part of YIRA's 70-test checkup. The doctor consultation included in every YIRA Family Health Plan can advise whether you need it, based on your results and history.
A YIRA Family Health Plan includes a 70-test full body checkup at home for one registered member, a doctor consultation for the family, a review of an elder's past reports, and dental and eye check-ups. Essential ₹999 a year (up to 4 family members registered); Complete ₹1,299 a year (up to 8, with ₹5 lakh accident cover for the buyer).
70-test checkup at home plus family care, from ₹999 a year
Essential ₹999 (one 70-test checkup, up to 4 family members registered) · Complete ₹1,299 (up to 8, with ₹5 lakh accident cover). Doctor consultation, dental and eye check-ups included. Pay after sample collection.
Frequently asked questions
What is a normal TSH level?
Many labs use roughly 0.4 to 4.0 mIU/L, but each lab prints its own range on the report. Your doctor interprets the value with your symptoms and other tests.
Do I need to fast for a thyroid test?
Usually not for TSH alone. If it is done with other tests that need fasting, follow the longest fasting instruction.
Is TSH enough to diagnose thyroid problems?
TSH is the usual first test. Doctors often add free T4 and sometimes T3 or thyroid antibodies to confirm the cause.
Related
Medically reviewed by Dr. N. S. Santosh Varma (MBBS, FIM, FIDM, FICCM; APMC/FMR 112686). Prepared by the YIRA health team · Last updated 1 October 2026. This page is general health information, not medical advice or a diagnosis. Reference ranges differ between labs; always discuss your results with a doctor. In an emergency, call 108 or go to the nearest hospital.