Thyroid Test (T3, T4, TSH) Explained: Normal Range and Results
The thyroid is a small, butterfly-shaped gland in your neck, but its hormones affect almost every part of the body — your weight, energy, heart rate, mood, periods and more. Thyroid problems are very common in India, especially among women, and a simple blood test is all it takes to check. Here is how to understand the three main thyroid test results: T3, T4 and TSH.
What T3, T4 and TSH Measure
- TSH (Thyroid Stimulating Hormone) is made by the pituitary gland in the brain. It tells the thyroid how much hormone to produce. TSH is usually the most sensitive first test for thyroid problems.
- T4 (Thyroxine) is the main hormone made by the thyroid.
- T3 (Triiodothyronine) is the more active form of thyroid hormone, mostly made from T4 in the body's tissues.
- Free T3 and Free T4 (FT3, FT4) measure only the unbound, active portion of these hormones and are less affected by pregnancy, birth control pills and other factors than total T3 and T4.
Thyroid Test Normal Range
Normal ranges vary between labs and methods, so always use the range printed on your report. Typical adult ranges are:
| Test | Typical adult range |
|---|---|
| TSH | About 0.4–4.5 mIU/L |
| Total T4 | About 5–12 µg/dL |
| Total T3 | About 80–200 ng/dL |
| Free T4 | About 0.8–1.8 ng/dL |
| Free T3 | About 2.3–4.2 pg/mL |
Ranges are different in pregnancy, which has trimester-specific targets, and in children. Your doctor will interpret your result against the right range.
How to Read Your Thyroid Results
| TSH | T4 / T3 | What it usually suggests |
|---|---|---|
| High | Low | Hypothyroidism (underactive thyroid) |
| High | Normal | Subclinical hypothyroidism — often monitored before treatment |
| Low | High | Hyperthyroidism (overactive thyroid) |
| Low | Normal | Subclinical hyperthyroidism |
| Low or normal | Low | Less commonly, a pituitary problem (central hypothyroidism) |
TSH moves in the opposite direction to thyroid hormones: when the thyroid is underactive, the brain releases more TSH to push it harder, so TSH goes up.
Symptoms That Suggest a Thyroid Test
- Underactive thyroid: tiredness, weight gain, feeling cold, constipation, dry skin, hair fall, low mood, heavy or irregular periods.
- Overactive thyroid: weight loss despite eating well, fast or irregular heartbeat, anxiety, tremors, sweating, poor sleep, frequent bowel movements.
- A swelling in the front of the neck (goitre).
- Planning a pregnancy, being pregnant, or a family history of thyroid disease.
How to Prepare for a Thyroid Test
- No fasting is needed for a thyroid test on its own. If it is part of a package with fasting tests, follow the package instructions — see which blood tests need fasting.
- Morning samples are preferred, because TSH naturally varies through the day. Testing at a similar time each time makes results easier to compare.
- If you take thyroid medicine, ask your doctor whether to take the day's dose after the sample is collected.
- Biotin supplements (often in hair, skin and nail supplements) can interfere with thyroid results. Tell your doctor, who may advise stopping them for a couple of days before the test.
Thyroid Test Price and Report Time
The Thyroid Profile Total (T3, T4 & TSH) is ₹490 with home sample collection included, and reports are usually ready within 6 hours. You can find it on our lab tests page. Thyroid testing is also part of every health package; the Aayushya Health Checkup 2 includes Free T3 and Free T4 for a more detailed view.
Book Your Test at Home
Home sample collection is available across India in the cities we serve. Book a Tata 1mg blood test in Delhi, Mumbai, Bangalore, Chennai or Kolkata, or see all our locations.
Frequently Asked Questions
What is the normal TSH level?
For most adults, TSH is typically about 0.4–4.5 mIU/L, though ranges vary by lab. Pregnancy has different, trimester-specific targets.
Do I need to fast for a thyroid test?
No. A thyroid test does not need fasting. A morning sample is preferred so results are comparable over time.
What does high TSH mean?
A high TSH usually means the thyroid is underactive (hypothyroidism). If T4 is still normal, it is called subclinical hypothyroidism. Your doctor will decide whether treatment is needed.
What is the difference between T3, T4 and Free T3, Free T4?
Total T3 and T4 measure all of the hormone in the blood, including the part bound to proteins. Free T3 and Free T4 measure only the active, unbound part and are less affected by pregnancy and some medicines.
Related Reading
- Vitamin D Test at Home: Normal Range, Price and Who Should Get Tested
- Which Blood Tests Need Fasting? A Simple Guide Before Your Test
- Full Body Checkup: What Tests Are Usually Included and Why They Matter
This article is for general information and does not replace advice from a qualified doctor. Reference ranges vary between labs, so always read your results against the range on your own report.