What is the Origin of Testosterone Free Fraction Measurement?

The measurement technique evolved from the need to accurately assess androgen status, as total testosterone levels can be misleading in conditions that alter SHBG concentration. Methodologies like equilibrium dialysis provide a gold standard for determining this active fraction.

What is the Mechanism of Testosterone Free Fraction Measurement?

The measurement isolates the free fraction, typically less than two percent of total testosterone, which is then quantified to determine the true tissue exposure to the hormone. This clinical insight allows for precise diagnosis of functional androgen deficiency and guides the titration of hormone replacement therapy to optimize therapeutic effect.

Testosterone Free Fraction Measurement ∞ Area

Testosterone Free Fraction Measurement

Meaning

A specialized laboratory test used in endocrinology to quantify the portion of total testosterone in the bloodstream that is not bound to carrier proteins, such as Sex Hormone-Binding Globulin (SHBG) and albumin. This unbound, or free, testosterone is the biologically active hormone that directly interacts with androgen receptors to elicit its effects on muscle, bone, and brain tissue. It is the most accurate clinical indicator of functional androgen status.