Below the range
Common causes of a low Free Thyroxine (Free T4)
- Hypothyroidism
- Severe non-thyroidal illness
Looking for the other direction? See what causes a high Free Thyroxine (Free T4).
All tests · Thyroid Function · Free Thyroxine (Free T4)
Below the range
What causes a low Free Thyroxine (Free T4)?
Normal range 0.8-1.8 ng/dL (10-23 pmol/L SI). Specimen: Serum. See the full Free Thyroxine (Free T4) reference page for critical values and nursing considerations.
What is the normal range for Free Thyroxine (Free T4)?
The standard teaching reference range for Free Thyroxine (Free T4) is 0.8-1.8 ng/dL in conventional units, or 10-23 pmol/L in SI units. This value is measured in serum.
| Specimen | Serum |
|---|---|
| Conventional range | 0.8-1.8 ng/dL |
| SI range | 10-23 pmol/L |
| Panel | Thyroid Function |
Full details, including nursing considerations, on the Free Thyroxine (Free T4) normal range page. Reference ranges vary by laboratory, method, age, sex, and population - always use the range printed on the actual result.
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