The sex hormone-binding globulin (SHbG) is a homodimeric glycoprotein which binds androgens and estrogens (sex hormones from the class of steroid hormones) with high affinity and specificity ‒ dihydrotestosterone, 2-methoxyestradiol, testosterone, androstenediol, androstandiol, estradiol and estrone with decreasing affinity.
SHbG transports the sex hormones in the blood, prevents their metabolic degradation and regulates the free, unbound share which can diffuse into the target cells. SHbG levels change over the course of life. SHbG concentrations in plasma are altered with different diseases.
SHbG determination is recommended as part of diagnostic clarification of hyperandrogenaemia in women, e.g. with suspected PCOS, and androgen deficiency in men. SHbG concentrations are determined in order to calculate the amount of free estradiol and testosterone.