What is the Origin of Free Hormone Availability Assessment?

This practice stems from the realization that carrier proteins, such as SHBG and corticosteroid-binding globulin (CBG), significantly modulate hormone bioavailability. The need for this assessment arose from clinical scenarios where total hormone levels appeared normal, yet symptoms suggested deficiency or excess. It represents a refinement in endocrine diagnostics, moving toward functional measurement.

What is the Mechanism of Free Hormone Availability Assessment?

The assessment typically involves equilibrium dialysis or validated immunoassay methods designed to separate the unbound hormone from its binding proteins before quantification. By measuring the free fraction directly, or calculating it using validated formulae based on total hormone and binding protein levels, we gain insight into receptor exposure. This directly reflects the signaling potential of the hormone within the target organ systems.

Free Hormone Availability Assessment ∞ Area

Free Hormone Availability Assessment

Meaning

Free Hormone Availability Assessment is the clinical evaluation of the unbound, biologically active fraction of steroid hormones circulating in the serum, as opposed to the total hormone level which includes protein-bound fractions. This assessment utilizes specialized assays to determine the actual concentration of hormone available to diffuse into tissues and interact with intracellular receptors. Understanding this free fraction is more predictive of physiological effect than total hormone levels alone, particularly in conditions involving changes in Sex Hormone-Binding Globulin (SHBG).