hCG, Intact ELISA

Human chorionic gonadotropin (hCG) is a two chain (alpha- and beta-subunits) glycoprotein hormone secreted by the chorionic tissue of the placenta and is normally found in urine and blood during pregnancy. Produced by the trophoblastic epithelium of the placenta, hCG acts to maintain the corpus luteum in the early stages of pregnancy.

Healthy, non-pregnant individuals have low (5 mIU/mL) to undetectable hCG concentrations in serum. During pregnancy, hCG concentrations increase to about 50 mIU/mL in the first week after conception and double every 1.5 to 3 days for the first six weeks. Levels continue to rise until the end of the first trimester, and then gradually fall to a lower level for the remainder of the pregnancy. After delivery, hCG returns to 5 mIU/mL and is usually undetectable several days postpartum.

The appearance of hCG soon after conception and its subsequent rise in concentration during early gestational growth make it an excellent marker for the early detection of pregnancy. Elevated serum hCG levels comparable to those observed in early pregnancy may also be associated with trophoblastic or nontrophoblastic neoplasms such as hydatidiform mole, choriocarinoma; therefore, the possibility of such diseases should be ruled out before a positive hCG result is considered for detection and monitoring of pregnancy.