Use
Free T4, the biologically active form of thyroxine, provides a clearer picture of thyroid hormone availability than total T4, which is influenced by binding proteins. Measuring free T4 is particularly useful for diagnosing and managing thyroid disorders, fine-tuning thyroid hormone replacement therapy, and evaluating symptoms like fatigue, weight changes, or mood disturbances. Regular monitoring can aid in achieving optimal metabolic function, energy levels, and overall well-being.
Free T4 may be indicated when conventional test results seem inconsistent with clinical observations. It is normal in subjects with high thyroxine-binding globulin hormone binding who are euthyroid (ie, free thyroxine should be normal in nonthyroidal diseases). It should be normal in familial dysalbuminemic hyperthyroxinemia.
FT4 may be increased with radiologic contrast agents, propranolol, amiodarone, and heparin. It may be decreased with carbamazepine (Tegretol®). Free T4 is a small part of total T4. Increased free T4 levels may occur in subjects with nonthyroid diseases. Such elevations are described as transient.
Preparation
Samples should not be collected during or soon after the administration of heparin. It is recommended to stop biotin consumption at least 72 hours prior to the collection of a sample.
$15.00