Abstract
Total and heat-stable serum alkaline phosphatase (heated at 65°C for 30 minutes) from normal and abnormal pregnancies were determined serially using a colorimetric method. In 71 normal pregnancies, enzyme activity increased gradually as gestation progressed. In 61 patients with preeclampsia and in patients with hypertension superimposed on preeclampsia, total and heat-stable enzyme were increased significantly over normal levels. This increase anticeded clinical signs. Enzyme activity was also increased in 19 patients with threatened abortion, and this increase was more significant in those with a previous history of threatened abortion. In prediabetic and diabetic patients, the reduction in enzyme levels varied, but a significant decrease from normal levels was noticed near term. It is concluded that changes in enzyme levels could be a manifestation of functional disturbances in the placenta, but before this test can be evaluated for routine use, further studies are required.