[Human chorionic gonadotropin and its subunits in normal and pathologic pregnancies].

Improved sensitivity and specificity of radioimmunoassays (RIAs) for hCG, hCG alpha and hCG beta have allowed measurements of these substances to become a powerful diagnostic aid applicable to several clinical disorders of pregnancy. In threatened abortion of the 1st trimester, the doubling time of hCG concentrations is significantly slower than in early normal pregnancies. Low levels of hCG are uniformly encountered in case of impending abortion. The overall predictive value of hCG determinations is 75-97%, whereas the predictive value of hCG alpha and hCG beta levels 88%. In patients progressing slowly to inevitable abortion, an increase in hCG alpha and/or the ratio hCG alpha: hCG is frequently observed. In ectopic pregnancies, sensitive new-generation tube tests and RIAs can detect urine or serum hCG in almost 100% of the cases. Abnormally low levels of hCG are encountered in about 85% of the patients. A significant increase in the ratio hCG alpha: hCG is observed. Toxemia of pregnancy is abided by significantly higher maternal levels of serum hCG, hCG alpha and hCG beta and by a lower ratio hPL: hCG than in normal pregnancies, or pregnancies complicated by isolated or chronic hypertension. It is concluded that in the above-mentioned pathological conditions of pregnancy, hCG is a reliable trophoblastic marker and that, additionally, hCG alpha could prove to be an index of chronic placental hypoxia.