1881 – SELco^® FT4

Intended Purpose

The SELco^® FT4 is a quantitative immunoassay for the determination of free Thyroxine (FT4) in human serum. The SELco^® FT4 is intended as an aid in the diagnosis of thyroid diseases in conjunction with other clinical and laboratory findings. The immunoassay is designed for manual professional in vitro diagnostic use.

Diagnostic Relevance

The circulation of thyroid hormones (thyroxine, T4 and triiodothyronine, T3) is distributed into two compartments; a major protein bound one, and a minor free fraction. Alterations in the total thyroid hormone in blood may be due to changes of binding protein concentrations, or synthesis of thyroid hormone. Thyroid disorders then exist due to persistent change of free unbound fractions. This indication serves as clinical hint, in that total T4 and T3 is dependent on the knowledge of functional levels of binding proteins, measured at length. As clinical hint, serum level of free T4 (FT4) correlates with secretion and metabolism rates of T4, and hence has been recommended as a reliable and significant diagnostic indicator of thyroid diseases, especially in ambiguous or borderline cases.