ACCESS FREE T4, 2X50 DET

The Access Free T4 assay is a paramagnetic particle, chemiluminescent immunoassay for the quantitative determination of free levels in human serum and plasma (heparin) using the Access Immunoassay Systems. The hypothalamic-pituitary-thyroid axis controls thyroid hormone synthesis, release, and action. Thyrotropin-releasing hormone (TRH) secreted from the hypothalamus stimulates the synthesis and release of thyrotropin of thyroid-stimulating hormone (TSH). TSH, in turn, stimulates the synthesis, storage, secretion, and metabolism of thyroxine (T4) and triiodothyronine (T3). Both free and bound forms of T4 and T3 are present in the blood. More than 99% of the T4 and T3 circulate in the blood bound to carrier proteins, leaving less than 1% unbound. It is this level of unbound or free hormone that correlates with the functional thyroid state in most individuals.