- Reporting Time:
- 6 Hrs
- Specimen Type:
- Home Collection:
- No special preparation required
To help evaluate thyroid gland function, diagnose thyroid disease, screen for hypothyroidism in newborns and to monitor effectiveness of treatment.
When there are signs and symptoms of thyroid disease, an abnormal TSH test result, as a screening test on newborns, while being treated for a thyroid disorders.
Free thyroxine (free T4) test evaluates the thyroid function and helps diagnose thyroid diseases, including hyperthyroidism and hypothyroidism. T4 and another hormone called triiodothyronine (T3) are produced by the thyroid gland. They control the basal metabolic rate of the body and are regulated by a feedback system via TSH which is secreted by the pituitary gland. Blood tests can measure total T4, free T4, total T3, or free T3. Most of the circulating T4 and T3 is bound to protein, while a small fraction is free. Unlike free T4 levels, the total T4 test can be affected by the amount of protein available in the blood. So the estimation of free T4 levels in the blood is considered more accurate reflection of the thyroid status. Free T4 helps detect hyperthyroidism and hypothyroidism and diagnose its cause, diagnose and monitor pituitary disorders, evaluate different thyroid disorders, monitor the treatment of thyroid disorders and aid in the diagnosis of female infertility.
1. Does pregnancy affect thyroid hormone levels?
Pregnancy can increase free T4 levels physiologically without any underlying thyroid disease.
2. Can free T4 levels be raised or lowered?
Generally free T4 does not respond to lifestyle changes. However free T4 levels can be raised with hormone replacement therapy.