TSH: normal range and what it means
The pituitary signal that controls your thyroid — the key screening test.
Normal range
Adult reference range.
- Low< 0.5 µIU/mL
- Optimal0.5 – 2.5 µIU/mL
- High≥ 2.5 µIU/mL
What it measures
The brain’s signal to the thyroid. High TSH suggests an underactive thyroid; low suggests overactive.
What moves it
Thyroid health, iodine, stress, and some medications.
How to bring it into range
Treating the underlying thyroid condition; adequate iodine and selenium.
How fast it responds
Weeks (it lags thyroid changes).
Also reported as: thyroid stimulating hormone
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Common questions
- What is a normal TSH level?
- Optimal: 0.5 – 2.5 µIU/mL. Adult reference range.
- What does a high TSH mean?
- A value above the reference band means TSH is outside the range typical for a healthy adult. A single reading is rarely conclusive on its own — what matters is the trend across draws and the other markers around it, which is why HealthOS reads the whole panel together rather than one number at a time.
- How do I improve my TSH?
- Treating the underlying thyroid condition; adequate iodine and selenium.
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Reference ranges are general-population guidance compiled from common clinical laboratories, not a diagnosis. Lab-to-lab ranges differ. Always read your results with your doctor.