TSH

Also known as: Thyroid Stimulating Hormone, Thyrotropin

Diabetes & Hormones Blood
Patient Friendly Summary

TSH works like a thermostat reading in reverse — when the thyroid slows down, TSH goes up to push it. A borderline value usually means a repeat test in 6–8 weeks, not instant medication.

What this test means

TSH is the brain's messenger to the thyroid. It moves opposite to thyroid activity: high TSH usually means an underactive thyroid, low TSH an overactive one.

Why it is done

It is done for weight changes, tiredness, hair fall, irregular periods, palpitations, fertility evaluation, and in pregnancy.

Understanding your value

If your value is high

High TSH may suggest hypothyroidism (underactive thyroid) — common, easily managed, and often picked up before symptoms are obvious.

If your value is low

Low TSH may suggest hyperthyroidism (overactive thyroid) or over-replacement with thyroid medicine.

About the normal range

A common range is about 0.4–4.5 mIU/L; targets differ in pregnancy and with treatment. Mildly raised values are often rechecked before treating.

When to consult a doctor

Consult your doctor for any out-of-range TSH, before changing thyroid medicine doses, and early in pregnancy if you have thyroid disease.

Frequently Asked Questions

It is done for weight changes, tiredness, hair fall, irregular periods, palpitations, fertility evaluation, and in pregnancy. Your doctor will decide if this test is right for your situation.

High TSH may suggest hypothyroidism (underactive thyroid) — common, easily managed, and often picked up before symptoms are obvious. This needs clinical correlation — always discuss your report with your doctor.

Low TSH may suggest hyperthyroidism (overactive thyroid) or over-replacement with thyroid medicine. This needs clinical correlation — always discuss your report with your doctor.

A single value rarely tells the whole story. Results need to be read together with your symptoms, history, and other tests. Please consult your doctor for a proper interpretation.

Quick Facts

  • TestTSH
  • Short formsThyroid Stimulating Hormone, Thyrotropin
  • Sample typeBlood
  • CategoryDiabetes & Hormones

Related Terms

High Low Borderline

Specialists

Endocrinology & Diabetology Gynecology & Obstetrics

Related Tests

Test
T3

One of the two active thyroid hormones.

Explore
Test
T4

The main hormone your thyroid gland produces.

Explore

Related Organs

Organ
Thyroid

The thyroid gland controls metabolism, energy, and weight. TSH, T3, and T4 blood tests show whether it is unde…

Explore
Disclaimer: This information is for patient education only and does not replace medical advice, diagnosis, or treatment. Always consult a qualified doctor.