Home Biomarkers Free Thyroxine
Thyroid PanelFree Thyroxine (fT4)
Active, unbound form of T4. Distinguishes primary from central thyroid disease.
What it measures
Active, unbound form of T4. Distinguishes primary from central thyroid disease.
What a high value can mean
Hyperthyroidism, Graves' disease, thyroiditis, levothyroxine overdose.
What a low value can mean
Hypothyroidism, severe illness, pituitary disease.
Conditions it helps assess
- Thyroid function severity
Reading these numbers in context
Reference ranges describe the central 95 % of a healthy reference population — 5 % of perfectly healthy people fall outside any given range by definition. A single mildly abnormal value is rarely meaningful on its own. blood-test.life always interprets values together with related biomarkers before flagging.