Thyroid Test in Chennai
A thyroid test is a blood test that measures how well your thyroid gland — a butterfly-shaped gland at the base of your neck — is functioning. The thyroid produces hormones that regulate your metabolism, energy levels, body temperature, and heart rate.
The most common thyroid test is the TSH (Thyroid Stimulating Hormone) test. TSH is produced by the pituitary gland and tells the thyroid how much hormone to make. High or low TSH levels are the earliest indicator of thyroid dysfunction, even before symptoms appear.
A complete thyroid profile includes TSH alongside T3 (Triiodothyronine) and T4 (Thyroxine) — the two hormones the thyroid actually produces. Together, these three markers give a full picture of thyroid health.
Why is a Thyroid Test Done?
Doctors recommend a thyroid test when a patient presents with symptoms that suggest thyroid dysfunction, or as part of a routine preventive health check. The test is used to:
- Diagnose hypothyroidism (underactive thyroid) — TSH high, T3/T4 low
- Diagnose hyperthyroidism (overactive thyroid) — TSH low, T3/T4 high
- Monitor patients already on thyroid medication (Eltroxin / Levothyroxine)
- Screen during pregnancy — thyroid disorders can affect fetal brain development
- Investigate unexplained weight changes, fatigue, or hair loss
- Evaluate infertility — thyroid imbalance is a common but overlooked cause
- Rule out thyroid issues before starting certain medications
Symptoms that warrant a thyroid test:
Hypothyroidism (Low thyroid) | Hyperthyroidism (High thyroid) |
Unexplained weight gain | Unexplained weight loss |
Fatigue and sluggishness | Rapid or irregular heartbeat |
Hair thinning or loss | Excessive sweating / heat intolerance |
Dry skin and constipation | Frequent bowel movements |
Feeling cold all the time | Tremors, nervousness, anxiety |
Depression, brain fog | Difficulty sleeping |
Irregular menstrual cycles | Bulging eyes (Graves’ disease) |
How to Prepare for a Thyroid Test
Good news: No fasting is required for TSH, T3, or T4 tests. You can eat and drink normally.
However, there are a few things to be aware of before your test:
- Morning (8–10 AM) is recommended as TSH levels fluctuate during the day. TSH is naturally highest in the early morning: Best time to test
- Inform MediLabs if you are taking Biotin supplements (Vitamin B7) — high-dose Biotin can interfere with thyroid test results. Stop Biotin 24–48 hours before the test: Medications
- If you are already on Levothyroxine / Eltroxin, take your dose AFTER the blood sample is drawn, not before. This gives the most accurate baseline reading: Thyroid medication timing
- Mention if you are pregnant — reference ranges for TSH differ during each trimester: Pregnancy
- Mention any recent major illness or hospitalisation as it can temporarily affect thyroid readings: Recent illness
ℹ There is no need to skip breakfast or avoid water. Arrive at any MediLabs branch or schedule a home collection at your convenience.
Parameters Included in Each Test
Parameter | Included In | What It Measures |
TSH (Thyroid Stimulating Hormone) | All packages | Pituitary signal to the thyroid — first marker checked |
T3 (Total Triiodothyronine) | Profile & Panel | Active thyroid hormone — elevated in hyperthyroidism |
T4 (Total Thyroxine) | Profile & Panel | Storage hormone — low in hypothyroidism |
Free T3 (FT3) | Complete Panel | Unbound active fraction — more clinically precise than total T3 |
Free T4 (FT4) | Complete Panel | Unbound T4 — preferred marker in pregnancy |
Anti-TPO Antibodies | Complete Panel | Detects Hashimoto’s thyroiditis (autoimmune hypothyroidism) |
Anti-Thyroglobulin (Anti-TG) | Complete Panel | Detects autoimmune thyroid disease; thyroid cancer monitoring |
Normal Reference Ranges
ℹ Reference ranges below are standard international values. MediLabs reports include your lab’s specific reference range alongside your result. Always consult your doctor for interpretation.
Parameter | Normal Range | Unit | Clinical significance |
TSH | 0.4 – 4.0 | mIU/L | >4.0 = hypothyroid; <0.4 = hyperthyroid |
TSH (Pregnancy T1) | 0.1 – 2.5 | mIU/L | Stricter range in first trimester |
TSH (Pregnancy T2) | 0.2 – 3.0 | mIU/L |
|
TSH (Pregnancy T3) | 0.3 – 3.0 | mIU/L |
|
Total T3 | 80 – 200 | ng/dL | High in hyperthyroidism, low in hypo |
Total T4 | 5.1 – 14.1 | µg/dL | Low indicates primary hypothyroidism |
Free T3 (FT3) | 2.3 – 4.2 | pg/mL |
|
Free T4 (FT4) | 0.8 – 1.8 | ng/dL | Preferred in pregnancy screening |
Anti-TPO | < 35 | IU/mL | >35 suggests Hashimoto’s or Graves’ |
Frequently Asked Questions
What is a thyroid test and what does it check?
A thyroid test is a blood test that measures levels of thyroid hormones (TSH, T3, T4) to assess how well your thyroid gland is functioning. At MediLabs Chennai, we offer TSH-only tests, a 3-marker Thyroid Profile, and a comprehensive Complete Thyroid Panel including antibody tests.
Is fasting required for a thyroid test?
No, fasting is not required for a thyroid test. You can eat and drink normally before your sample is collected. However, if you are on thyroid medication (like Levothyroxine), it is best to have your blood drawn before taking your morning dose to get the most accurate result.
How long does a thyroid test report take?
TSH, T3, and T4 results are available within 6–8 hours of sample collection. Antibody tests (Anti-TPO, Anti-TG) may take 12–24 hours. Reports are delivered digitally via WhatsApp or email and can also be downloaded from the MediLabs portal.
Can I book a thyroid test with home collection in Chennai?
Yes. MediLabs offers home blood collection for thyroid tests across all major areas in Chennai . Book online at medilabs.co.in or call +91 98844 62109.
What is a normal TSH level?
For a non-pregnant adult, a normal TSH level is between 0.4 and 4.0 mIU/L. A TSH above 4.0 mIU/L suggests hypothyroidism (underactive thyroid). A TSH below 0.4 mIU/L suggests hyperthyroidism (overactive thyroid). During pregnancy, the normal range is stricter — ideally below 2.5 mIU/L in the first trimester. Always have your result interpreted by your doctor in context of your symptoms.
What is the difference between TSH, T3, and T4 tests?
TSH (Thyroid Stimulating Hormone) is produced by the pituitary gland and is the most sensitive marker for thyroid dysfunction — it is always tested first. T3 and T4 are the hormones produced by the thyroid gland itself. When TSH is abnormal, T3 and T4 help determine the type and severity of the thyroid disorder. Free T3 and Free T4 are the unbound, active fractions and are more clinically accurate, especially during pregnancy.
Is MediLabs NABL accredited for thyroid testing?
Yes. MediLabs is NABL accredited, which means our testing processes, equipment, and quality systems meet national standards set by the National Accreditation Board for Testing and Calibration Laboratories. All thyroid tests are processed in our accredited central reference laboratory using fully automated analysers, ensuring accuracy and reproducibility of results.
Book Your Thyroid Test in Chennai
Option | How to Book | Available Time |
Walk-in (any branch) | Visit any branches — no appointment needed | Mon–Sun, 7 AM – 8 PM |
Home sample collection | Call +91 98844 62109 or book at medilabs.co.in | 7 AM – 11 AM (early morning slots) |
Online appointment | medilabs.co.in → Book a Test → Select Thyroid | Available 24/7 online |
+91 98844 62109 | 
medilabs.co.in | Book a test