How reports print it
TSHТТГТиреотропный гормонТиреостимулирующий гормонТиротропинТиреотропинThyroid stimulating hormoneThyroid-stimulating hormoneThyrotropinTSH 3rd generation
What it shows
A pituitary hormone that steers the thyroid. When thyroid hormones are low, TSH rises; when they are high, it falls.
Units and conversion
Base unit: mIU/L. Most common on Russian reports: µIU/mL.
- 1 µIU/mL = 1 mIU/L
Typical ranges
Your laboratory’s range comes first — it is printed on the report next to the result. Below is one laboratory’s adult range with its method: a reference, not a rule.
| Who | Range, mIU/L |
|---|---|
| Adults, 18–20 years | 0.51–4.3 |
| Adults, 21 years and older | 0.27–4.2 |
Range source: Лаборатория Хеликс — Тиреотропный гормон (ТТГ)
Good to know
µIU/mL, mIU/L and mU/L are the same. Ranges depend on the platform: Helix gives 0.27–4.2 for adults over 20. Pregnancy has different ranges: per Helix, TSH can be higher in the third trimester.
Why it can be higher
Common reasons discussed with a doctor. This is not a diagnosis.
- An underactive thyroid
- Recovery from a severe illness
- Some medicines
- Age: on average TSH rises slightly over the years
Why it can be lower
- An overactive thyroid
- Taking thyroid hormones
- The first trimester of pregnancy
- Glucocorticoids
What to ask a doctor
- Should free T4 and TPO antibodies be checked?
- When to repeat it?
Whom to see
A GP or internist; then an endocrinologist.