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SHBG ELISA kit
The SHBG ELISA kit is intended for quantitative determination of sex hormones-binding globulin (SHBG) in human serum.
Sex hormones binding globulin (SHBG) is a serum protein that binds steroid sex hormones. SHBG is synthesized in the liver. It is a dimeric glycoprotein with molecular mass of 80 to 100 kDa (depending on glycosilation).
Steroid hormones circulate in blood free or bound by albumin or corresponding specific protein (SHBG in case of sex steroids). The sex steroid hormone fraction not bound to SHBG (=bioavailable hormone) can perform regulatory function in target cells. Steroids that are bound to albumin are also bioavailable because of weak bindings that cannot prevent diffusion of hormons into the target cells.
SHBG shows maximal affinity to androgens and a lesser one to estrogens. SHBG synthesis is also affected by sex steroids. Estrogens show a stimulating effect, whereas androgens inhibit the synthesis. SHBG concentration increases in the case of hyperthyroidism or hyperestrogenia (luteal phase of the cycle, pregnancy, intake of estrogen-containing oral contraceptives, cyrrhosis ...). In adult men the concentration of bioavailable testosterone decreases with age due to increased concentration of SHBG. In women SHBG concentration decrease correlates with hyperandrogenic status (polycystic ovary syndrome, congenital dysfunctions of adrenal cortex, hirsutism). Moderate decrease in SHBG concentration is also observed in cases of hypothyroidism, Cushing disease, hyperprolactinemia, acromegalia and after administering androgens or progestins possessing an androgenic effect. SHBG concentration is used to calculate the free androgen index (a ratio between concentrations of total testosterone and SHBG).