What is the Origin of SHBG Transport Capacity?

SHBG is a specific glycoprotein produced primarily by the liver, central to steroid endocrinology. Transport Capacity describes its binding affinity and saturation potential. The concept is vital because many pathologies are linked not to low total hormone but to poor bioavailability governed by SHBG levels, which are sensitive to insulin and thyroid status.

What is the Mechanism of SHBG Transport Capacity?

SHBG binds sex steroids with high affinity, effectively sequestering them from receptor interaction. Its production rate is significantly downregulated by hyperinsulinemia and upregulated by hypothyroidism, creating dynamic shifts in free hormone availability. Therefore, optimizing insulin sensitivity and thyroid hormone action directly influences this transport capacity, thereby modulating the free hormone pool available for tissue signaling.

SHBG Transport Capacity ∞ Area

SHBG Transport Capacity

Meaning

SHBG Transport Capacity refers to the functional measure of Sex Hormone-Binding Globulin’s ability to bind and transport steroid hormones, primarily testosterone and estradiol, in the circulation. This capacity dictates the amount of hormone available to target tissues, meaning high SHBG can effectively lower free, biologically active hormone levels despite adequate total production. Understanding this capacity is essential for interpreting hormonal panels correctly. It defines the effective hormone delivery system.