Thyroid
Free T4
Normal Range:0.8-1.8 ng/dL
Optimal Range:1.2-1.5 ng/dL
What is Free T4?
Free T4 (thyroxine) is the unbound, active form of the main hormone produced by your thyroid gland. It's converted to the more active T3 in your tissues.
Why Free T4 Matters
Free T4 gives a direct measure of available thyroid hormone in your blood, independent of protein levels that can affect total T4 measurements.
Symptoms of Low Free T4
- Fatigue
- Weight gain
- Depression
- Constipation
- Dry skin
- Hair loss
Symptoms of High Free T4
- Anxiety
- Weight loss
- Rapid heartbeat
- Tremors
- Sweating
- Difficulty sleeping
Reference Ranges
| Range Type | Minimum | Maximum | Unit |
|---|---|---|---|
| Normal Range | 0.8 | 1.8 | ng/dL |
| Optimal Range | 1.2 | 1.5 | ng/dL |