Quantitative evaluation of human placental aromatase in abnormal pregnancy--anencephalus and hydatidiform mole

To determine why estriol (E3) levels in the urine and serum are extremely low in pregnancies with anencephalus or hydatidiform mole, both the aromatase activity and the tissue P450arom concentration in solubilized fractions of placental or mole microsomes was measured. The aromatase activity was measured by tritiated water assay and the tissue P450arom concentration was determined by sandwich enzyme-linked immunosorbent assay (ELISA). Consequently, any tissue P450arom concentration was at a lower level than the regression line for that in normal placenta. The aromatase activity also showed a tendency to be lower than that in normal placenta. These results therefore suggest that a decrease of E3 in these abnormal pregnancies would result mainly in a lower level of tissue P450arom concentration.