What is the Origin of Bioavailable Hormone Assays?

The concept stems from the fundamental principles of endocrinology and pharmacokinetics, specifically the widely accepted "free hormone hypothesis" which posits that only unbound hormones are biologically active at the cellular level. The term "assay" originates from the Old French assai, meaning to try or test, reflecting the analytical and quantitative nature of the measurement.

What is the Mechanism of Bioavailable Hormone Assays?

The assays typically employ advanced methods like equilibrium dialysis or calculated indices to separate or accurately estimate the non-protein-bound and albumin-bound hormone fractions. These methods account for the strong binding capacity of Sex Hormone-Binding Globulin (SHBG) and the weaker binding to albumin, which together largely determine the effective free hormone concentration. This clinical measurement allows practitioners to assess the genuine endocrine signal influencing cellular receptor occupancy and function.

Bioavailable Hormone Assays ∞ Area

Bioavailable Hormone Assays

Meaning

These are specialized laboratory tests designed to measure the fraction of a hormone that is unbound to plasma proteins or only weakly bound to albumin, representing the portion immediately accessible to target tissues. Measuring bioavailable hormones provides a more accurate clinical picture of true hormonal activity compared to merely assessing total hormone levels alone. This diagnostic precision is crucial for effective treatment personalization and dosage titration in endocrinology.