Sex hormone-binding globulin

Sex hormone-binding globulin (SHBG) is a glycoprotein that binds to sex hormones, specifically testosterone and estradiol. Other steroid hormones such as progesterone, cortisol, and other corticosteroids are bound by transcortin. SHBG is produced by the liver and is released into the bloodstream.

Function

SHBG controls the amount of testosterone that the body's cells can use. It carries testosterone through the bloodstream to the cells. When testosterone is bound to SHBG, it is not available for the cells to use. This is referred to as "bound testosterone." The testosterone that is not bound to SHBG is called "free testosterone."

Role in disease

Abnormal levels of SHBG can result in a variety of medical conditions. High levels of SHBG may be associated with polycystic ovary syndrome (PCOS), while low levels can lead to conditions such as type 2 diabetes, thyroid disease, and acromegaly.

Measurement

The level of SHBG in the blood can be measured with a simple blood test. This test can help doctors diagnose conditions related to abnormal levels of SHBG.

See also

• Hormone
• Endocrinology
• Steroid hormone