Alteration of free hCG subunits secretions in ectopic pregnancy

Abstract

Abstract. Intact hCG and free α and β hCG subunits were simultaneously measured by specific radioimmunoassays in blood samples from pregnant women with normal pregnancy (n = 87; control group) or with a ruptured ectopic pregnancy (n = 35) between 5 and 14 weeks. Since the lower 95% confidence limit of the hCG levels encountered in normal pregnancies was at 1200 ng/ml, the pathological group has been subdivided in 2 subgroups: A (n = 17) if hCG was greater and B (n = 18) if hCG was lower than this limit. In subgroup A, mean hCG and β hCG were significantly lower than in the control group in contrast to a tendency to secrete and/or release more α hCG, as reflected by a significantly increased ratio of α hCG/hCG. Thus, the ectopically implanted trophoblast, even when able to produce normal amounts of hCG, undergoes an impairment of its ability to synthesize and/or release free β hCG but not free α hCG, of which the synthesis and/or release appears to become even enhanced. In subgroup B, mean hCG, α hCG and β hCG levels were all dramatically suppressed but there was surprisingly less alteration of the synthesis and/or release of free β hCG. These alterations of the relative secretions of the free hCG subunits, compared to those occurring for various glycoproteic hormones in pathological circumstances, reflect probably early alterations of the trophoblast.