HCG is produced in the placenta during pregnancy and its role serves to maintain the corpus luteum during pregnancy. HCG exists as a number of isohormones and the serum of pregnant women contains mainly intact hCG. Elevated values of hCG during pregnancy may serve as an indication of chorionic carcinoma, hydatiform mole or multiple pregnancy. Depressed values indicate threatening or missed abortion, ectopic pregnancy, gestosis or intra-uterine death. Elevated hCG concentrations not associated with pregnancy are found in patients with other diseases, such as tumors of the germ cells, ovaries, bladder, pancreas, stomach, lungs and liver.