The normal T4 range in adults can range from 0.9 to 1.9 nanograms per deciliter (ng/dL). Free T4 levels vary in children according to age. If the T4 level is outside the normal range, please consult a doctor to interpret the results and determine a treatment plan.
Along with T4, T3 is also a major hormone produced by the thyroid gland that helps regulate the body’s metabolism.
The FT4 blood test measures the amount of T4 that is not bound to the proteins in the body and is available for use. This will help ensure if the thyroid gland is functioning well or not. Your doctor may advise a T4 test if a thyroid-stimulating hormone (TSH) test has come back with abnormal results.
- High levels of FT4 and low TSH can indicate that the thyroid is overactive – hyperthyroidism.
- Low levels of FT4 and high TSH can indicate that the thyroid is not active enough – hypothyroidism.
- Low levels of FT4 and TSH can indicate that the pituitary gland is not active enough – hypopituitarism.
Disclaimer: Please consult your doctor for interpreting the test reports.