What is the Origin of Free Testosterone Fractionation?

Fractionation derives from separating components, applied here to the binding equilibrium of testosterone in plasma, linking to the root testis (testicle) and steros (solid). Clinically, the need arose because total testosterone often fails to reflect tissue availability, especially when SHBG levels fluctuate due to metabolic or aging factors.

What is the Mechanism of Free Testosterone Fractionation?

This analysis typically employs equilibrium dialysis or validated immunoassay methods to separate the minute free fraction from the bound components. The resulting data allows clinicians to calculate bioavailable testosterone, factoring in SHBG levels which are often regulated by hepatic function and insulin status. By understanding this partition, we accurately assess the functional androgen pool available for anabolic and regulatory signaling within the body's tissues.

Free Testosterone Fractionation

Meaning

Free Testosterone Fractionation is the laboratory assessment that quantifies the unbound, biologically active fraction of total testosterone circulating in the serum, distinct from that bound to Sex Hormone-Binding Globulin (SHBG) or albumin. Accurate measurement of this free fraction is critical because only unbound hormone can readily interact with androgen receptors to exert physiological effects. This assay provides superior diagnostic insight into androgenic status compared to total testosterone alone.