What It Measures#
A Thyroid Function Test (TFT) evaluates the performance of your thyroid gland — a butterfly-shaped gland in your neck that controls metabolism, energy, heart rate, and body temperature. The panel includes:
- TSH (Thyroid Stimulating Hormone) — produced by the pituitary gland; the most sensitive screening test for thyroid disorders. See also: TSH Test.
- Free T4 (Thyroxine) — the main hormone produced by the thyroid; regulates metabolism.
- Free T3 (Triiodothyronine) — the active thyroid hormone; most T3 is converted from T4 in tissues.
Thyroid disorders affect an estimated 4.2 crore Indians. Hypothyroidism (underactive thyroid) is far more common than hyperthyroidism, especially in women and in iodine-deficient regions.
Who Should Get Tested#
- Women above 30 years — thyroid disorders are 5–8× more common in women.
- Pregnant women — uncontrolled thyroid can affect foetal brain development.
- Anyone with symptoms: unexplained weight gain/loss, fatigue, hair loss, cold/heat intolerance, irregular periods, or mood changes.
- People with a family history of thyroid disease or autoimmune conditions.
- Patients with type 1 diabetes, PCOD/PCOS, or Down syndrome.
- Newborns — TSH screening is part of neonatal screening programs.
How to Prepare#
- No fasting required, but early-morning testing (before 10 AM) is preferred as TSH levels are highest in the morning and decline through the day.
- If you are on thyroid medication (levothyroxine), take the sample before your morning dose.
- Inform your doctor about biotin supplements — high-dose biotin can interfere with thyroid assays.
Understanding Your Results#
| Parameter | Normal Range | Low (Hypothyroid) | High (Hyperthyroid) | |-----------|-------------|-------------------|---------------------| | TSH | 0.4–4.0 mIU/L | > 4.0 mIU/L | < 0.4 mIU/L | | Free T4 | 0.8–1.8 ng/dL | < 0.8 ng/dL | > 1.8 ng/dL | | Free T3 | 2.3–4.2 pg/mL | < 2.3 pg/mL | > 4.2 pg/mL |
Subclinical hypothyroidism (mildly elevated TSH with normal T4) is very common in India and may or may not require treatment. Your endocrinologist will decide based on symptoms, antibody status, and TSH level.
Related Tests#
- TSH Test — standalone screening test if only TSH is needed.
- Vitamin D Test — deficiency is common alongside thyroid issues.
- Vitamin B12 Test — often low in hypothyroid patients.
- Iron Studies — thyroid dysfunction can impair iron absorption.
- Lipid Profile — hypothyroidism raises cholesterol levels.
Booking & Home Collection#
Book a thyroid function test on PingMeDoc with convenient early-morning home collection. Fasting is not required, but early slots ensure the most accurate TSH reading.