What is the Origin of Serum Free Fraction Analysis?

The necessity for this more advanced analysis arose from the understanding in endocrinology that only the free fraction of a hormone is capable of diffusion into tissues and initiating a cellular response. The methodology is a crucial refinement of standard total hormone assays, moving clinical assessment toward functional biology.

What is the Mechanism of Serum Free Fraction Analysis?

The free fraction is typically determined either by physical separation techniques like equilibrium dialysis or by calculating it using measured total hormone, SHBG, and albumin levels. High levels of carrier proteins can sequester a large percentage of the hormone, leading to a low free fraction despite a seemingly normal total level. Clinical interpretation of this metric is essential for diagnosing functional hormone deficiencies or excesses, particularly for key sex and thyroid hormones.

Serum Free Fraction Analysis ∞ Area

Serum Free Fraction Analysis

Meaning

Serum Free Fraction Analysis is a specialized laboratory technique used to accurately measure the concentration of the biologically active, unbound portion of a hormone in the bloodstream. Unlike total hormone measurements, which include hormones bound to carrier proteins like Sex Hormone-Binding Globulin (SHBG) or albumin, the free fraction represents the hormone immediately available to diffuse into tissues and bind to target cell receptors to exert its physiological effect. This analysis provides a more accurate assessment of functional hormonal status than total levels alone.