A thyroid report can look like a page of strange letters. Let us decode it in simple words so you can understand what your doctor is looking at.
TSH: the first and main test
TSH is made by the pituitary gland in the brain. It tells the thyroid how hard to work. When thyroid hormones are low, TSH rises. When they are high, TSH falls. That is why it is the best first test. Many labs show a normal range of about 0.4 to 4.5 mIU/L, but ranges differ between labs and in pregnancy.
Free T4 and free T3
These are the actual hormones in your blood. Free T4 is the main one. Doctors check it when TSH is abnormal. Free T3 is mostly useful in suspected hyperthyroidism. In hypothyroidism, T3 is often not needed.
Anti-TPO antibodies
These show whether the body’s defence system is attacking the thyroid, as in Hashimoto’s. A positive result means a higher chance of thyroid problems in the future, even if TSH is normal today.
Ultrasound of the neck
This looks at the size of the gland and any nodules. It is not needed for every person with a thyroid problem.
Tips for a good test
- No special fasting is needed for TSH, though many labs prefer morning samples.
- If you take levothyroxine, take the tablet after the blood sample on the day of the test.
- Biotin supplements (often in hair and nail products) can give false results. Tell your doctor and stop them for a few days before testing, if advised.
- Compare reports from the same lab when possible.
One last point
Treat the person, not only the report. If TSH is slightly off but you feel well, your doctor may simply repeat the test in a few weeks.
You can get your thyroid tests and doctor review at our clinic in Gopanpally, Gachibowli. Our lab hours are 6 AM to 11 PM daily, which suits those working in the Financial District or Nanakramguda. Contact us to plan a visit.
Keep reading
- Mildly raised TSH: do I need medicine?
- What is the thyroid?
- Hashimoto’s thyroiditis
- Your thyroid questions, answered
Your family doctor,
Akhila Reddy
MBBS, DNB (Family Medicine) | TSMC Reg. No. APMC/FMR/74261
AMC Hospital, Gopanpally, Gachibowli, Hyderabad
This article is for general health education and does not replace a check-up. Every person is different, so please speak to your doctor before changing any medicine. In an emergency, call 108 or go to the nearest hospital.
References
- Garber JR et al. Clinical practice guidelines for hypothyroidism in adults (ATA/AACE). Thyroid 2012;22(12):1200-1235.
- Alexander EK et al. 2017 Guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and the postpartum. Thyroid 2017;27(3):315-389.
- U.S. Food and Drug Administration. Safety communication: biotin interference with lab tests. 2019. https://www.fda.gov