What is the Origin of Free Testosterone Fractioning?

This terminology is derived from analytical endocrinology, specifically the need to separate circulating hormones into their bound and unbound states to reflect physiological availability accurately. It acknowledges that protein binding significantly modulates steroid hormone access.

What is the Mechanism of Free Testosterone Fractioning?

Fractioning utilizes validated methods, often equilibrium dialysis or calculated estimations based on SHBG levels, to quantify the unbound testosterone. This unbound fraction then readily diffuses across cell membranes to interact with intracellular androgen receptors. The efficiency of this partitioning is highly dependent on SHBG concentration, which itself is modulated by factors like thyroid hormones and liver function.

Free Testosterone Fractioning ∞ Area

Free Testosterone Fractioning

Meaning

The analytical process of determining the proportion of total testosterone that is unbound by plasma proteins like Sex Hormone-Binding Globulin (SHBG) or albumin, representing the biologically active fraction available for cellular uptake. Accurate fractioning is essential because only this free component can exert androgenic effects on target tissues. Clinically, this often supersedes total testosterone measurements for assessing androgen status.