Thyroid Tests (TSH, T3, T4): The Tiny Gland Behind Big Symptoms
2026-07-02 · 2 min read
Unexplained weight gain. Constant tiredness. Hair fall. Feeling cold when everyone else is fine. Irregular periods. These everyday complaints share one common suspect: the thyroid, a butterfly-shaped gland in your neck that sets the speed of your metabolism.
TSH first — the smart screening test
TSH (Thyroid Stimulating Hormone) isn't made by the thyroid at all — it's the pituitary gland's instruction signal to the thyroid. That makes it exquisitely sensitive:
- High TSH → the pituitary is shouting because the thyroid is underactive (hypothyroidism — the common one in India, especially in women)
- Low TSH → the thyroid is overactive and the pituitary has gone quiet (hyperthyroidism)
For routine screening, TSH alone is often enough — which is why it appears in almost every health package.
When T3 and T4 join in
If TSH is abnormal, the full thyroid profile (T3, T4, TSH) shows how far things have drifted. T4 and T3 are the actual thyroid hormones; their levels distinguish mild "subclinical" cases (abnormal TSH, normal hormones) from overt disease that clearly needs treatment.
Who should test?
- Women over 30 — roughly 1 in 10 develops a thyroid disorder
- Anyone planning pregnancy or currently pregnant (thyroid affects the baby's development)
- People with the symptoms above, or a family history
- Anyone on thyroid medication: every 6–12 months to keep the dose right
Preparation
None needed — no fasting. If you take thyroxine (Eltroxin/Thyronorm), give the sample before your morning tablet for a consistent reading.
The good news
Thyroid disorders are among the most treatable conditions in medicine: one small daily tablet, correctly dosed, returns most people to completely normal life. The test is the only way to get the dose right.
This article is for general information and is not a substitute for medical advice. Always discuss your results with your doctor.