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Hormone Binding Proteins

Meaning

Hormone Binding Proteins (HBPs) are specialized proteins synthesized primarily in the liver that circulate in the bloodstream and bind to steroid and thyroid hormones, regulating their transport, metabolism, and bioavailability to target tissues. Key examples include Sex Hormone-Binding Globulin (SHBG) and Thyroid-Binding Globulin (TBG). These proteins are crucial regulators of the endocrine system, as only the unbound, or “free,” fraction of a hormone is biologically active and able to diffuse into cells to exert its effect. Clinical assessment of HBPs is essential for accurately interpreting total hormone levels and diagnosing conditions like hyper- or hypo-androgenism.