The TSH normal range is the reference window laboratories use to classify thyroid function. While 0.4–4.0 mIU/L is the standard for most adults, your ideal range depends on your age, health status, and whether you are pregnant.
General Adult TSH Range
For healthy adults aged 18 to 60, the typical TSH reference range is:
- 0.4 to 4.0 mIU/L (ATA/AACE guidelines)
- Some labs use 0.5 to 5.0 mIU/L
TSH Normal Range by Age Group
| Group | TSH Range (mIU/L) |
|---|---|
| Newborns | 1.0 – 39.0 |
| Children (1–10) | 0.7 – 5.7 |
| Adolescents | 0.5 – 4.3 |
| Adults | 0.4 – 4.0 |
| Elderly (70+) | 0.4 – 5.5 |
TSH Normal Range During Pregnancy
Pregnancy suppresses TSH due to rising hCG levels. Trimester-specific ranges are:
- First trimester: 0.1 – 2.5
- Second trimester: 0.2 – 3.0
- Third trimester: 0.3 – 3.0
Optimal vs. "Normal" TSH
Some functional medicine practitioners consider 1.0–2.5 mIU/L the optimal range for symptom-free adults. If your TSH is technically "normal" but you still have symptoms, a complete thyroid panel may provide answers.
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