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Availability

Meaning

In the context of hormonal health, availability refers to the fraction of a substance, such as a hormone or a nutrient, that is present in a form capable of exerting a biological effect at the target tissue. This clinical concept is distinct from the total concentration measured in the bloodstream, as many hormones are bound to carrier proteins like Sex Hormone-Binding Globulin, rendering them temporarily inactive. The readily usable portion is often termed “free” or “bioavailable,” and it dictates the true physiological impact. Optimal availability ensures adequate signaling for cellular function and metabolic regulation.