TSH
TSH is a hormone from the pituitary gland that instructs the thyroid how many thyroid hormones to produce. It acts like a thermostat: if there is too little hormone, TSH rises (driving the thyroid); if too much, it falls.
| Rating | Range | What it means |
|---|---|---|
| Worth improving | below 0.4 mIU/L | Low TSH — possible overactive thyroid; seek advice. |
| Good | 0.4 – 4 mIU/L | TSH within the reference range. |
| Worth improving | 4 – 10 mIU/L | Slightly elevated (subclinical) — monitor fT4/antibodies. |
| Talk to a doctor | 10 mIU/L and above | Elevated — possible underactive thyroid; seek advice. |
This marker also has 4 age- or sex-specific range sets in the app — the table shows the general one.
Why it matters
ETA: the main thyroid screening test; an abnormal result indicates an under-/overactive thyroid (energy, weight, mood).
If it’s low
Low TSH often means too much thyroid hormone (hyperthyroidism — palpitations, tremor, weight loss, anxiety) or a medication effect.
If it’s high
Elevated TSH means the brain is driving the thyroid because there is too little hormone — often the start of hypothyroidism (fatigue, feeling cold, weight gain, dry skin).
What to do
TSH alone is not a diagnosis — with an abnormal result, fT4 is added (and antibodies if needed). Treatment is a medical matter; lifestyle is only supportive.
Read together with
fT4 (free thyroxine) · fT3 (free triiodothyronine) · Anti-TPO antibodies
Part of the guide: Thyroid →
Articles about this marker
- AI blood test analyzer: what it can and cannot do (and how to use ChatGPT safely)Reading your report
- Blood test reference values — table by test for adultsReading your report
- Blood tests before pregnancy: what to check before you conceiveLife stages
- ChatGPT prompt for blood test results: a safe template and what to checkReading your report
- Fatigue: which blood tests explain it — and which don'tSymptom → test
- Hair loss: which blood tests reveal the cause — and when they do notSymptom → test
This content is for information only and is not a substitute for medical advice. Talk to your doctor about your results.
Your number, not the average
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