Endometrial and plasma concentrations of pregnancy-associated plasma protein-A (PAPP-A)

Pregnancy-associated plasma protein-A (PAPP-A), oestradiol and progesterone levels have been measured by radioimmunoassay in plasma and in endometrial homogenates of 20 women undergoing hysterectomy. Results were grouped according to the histological stages of the endometrium. In plasma, oestradiol and progesterone concentrations changed from proliferative to secretory stages in the well-established pattern of the menstrual cycle, but PAPP-A levels did not change. In endometrium, oestradiol levels were high during the proliferative stage and low in inactive and secretory endometrium. Endometrial PAPP-A and progesterone concentrations increased from inactive to secretory stages, but only the increase in PAPP-A was statistically significant. A positive correlation observed between endometrial PAPP-A concentrations and plasma oestradiol/progesterone ratio suggests a possible hormonal control for the presence of PAPP-A in the uterus.