TSH Normal Range by Age: What Your Thyroid Report Means

Thyroid Stimulating Hormone (TSH) is the single most useful screening test for thyroid function. For most non-pregnant adults, the typical reference range is roughly 0.4–4.5 mIU/L, though the exact range printed on your report depends on the lab's method — always read your value against that range.

Typical TSH reference ranges

• Adults (18–60): about 0.4–4.5 mIU/L
• Adults over 60: slightly higher values can be normal, up to ~6 mIU/L in some labs
• Pregnancy: trimester-specific ranges apply — first trimester is usually below ~2.5–3.0 mIU/L
• Children: ranges differ by age; paediatric reports carry their own ranges

What a high TSH means

A high TSH usually points to an underactive thyroid (hypothyroidism) — the pituitary is pushing the thyroid harder. Common symptoms include tiredness, weight gain, hair fall and feeling cold. Mildly raised values (4.5–10) are often rechecked with a full T3-T4-TSH profile before starting treatment.

What a low TSH means

A low TSH suggests an overactive thyroid (hyperthyroidism), with symptoms like palpitations, weight loss, anxiety and heat intolerance. It can also occur if a thyroid medicine dose is too high.

When to test

Test if you have symptoms, a family history, are planning pregnancy, or once every 1–2 years after 35 as part of a routine checkup. No fasting is needed, and a morning sample gives the most consistent result. Your doctor should interpret the value in context — a single mildly abnormal TSH is usually rechecked after 6–8 weeks.