Total T4
Total T4 measures the total amount of thyroxine in the blood, including both protein-bound and free forms. Thyroxine is the primary hormone released by the thyroid gland.
Category: Thyroid Panel
Also known as: total t4, t4, thyroxine, thyroxine total, ukupni t4
Reference range: 5–12 µg/dL (Source: ABIM)
Standard unit: µg/dL
High values may indicate
High total T4 may indicate hyperthyroidism, Graves' disease, thyroiditis, or elevated thyroid-binding globulin (e.g., from pregnancy or estrogen use).
Low values may indicate
Low total T4 may indicate hypothyroidism, pituitary insufficiency, severe illness, or decreased thyroid-binding globulin.
Frequently asked questions
- What is a normal Total T4 level?
- A typical reference range for Total T4 is 5–12 µg/dL (source: ABIM). Reference ranges vary by laboratory, age, and sex, so always compare against the range on your own lab report.
- What units is Total T4 measured in?
- Total T4 is most commonly reported in µg/dL. Labs in different countries may use other units — you can convert between them with BloodId's blood test unit converter.
- Where do Total T4 reference ranges come from?
- BloodId uses ABIM standard reference ranges and educational information from MedlinePlus (see our methodology). Reference ranges still vary by lab, age, and sex, so always compare against your own report.
- Can I track Total T4 over time?
- Yes. Upload results from any lab and BloodId charts your Total T4 over time against its reference range, so you can see whether the trend is rising, falling, or stable.