Serum alkaline phosphatase: its isoenzymes, 5-nucleotidase and sialic acid in normal and abnormal pregnancies

ABSTRACT

Alkaline phosphatase [ALP] enzyme activity and its isoenzymes were determined in serum by heat inactivation and chemical inhibition by urea, L-phenylalanine and EDTA. Sialic acid concentration and 5- nucleotidase [5-NT] activity were also measured in serum of 381 consecutive pregnant cases seen in the obstetric outpatient clinic and Ward of Jordan University Hospital. These included normal pregnancies and pregnancies associated with other conditions such as toxemias, diabetes mellitus, and also abortion cases. This study was undertaken, to assess the activity of ALP and its isoenzymes in normal and abnormal pregnancies with a view to evaluate their usefulness as parameters of placental function. The changes in the concentration of serum sialic acid and 5-NT activity in all subjects were also studied. The cases in study were divided into three groups [trimesters]. The results from this study showed a gradual increase in placental ALP isoenzymes which reaches a maximum at term. A definite enzyme pattern of ALP was seen in normal and abnormal pregnancies and inhibition by EDTA is a valuable index for the placental function. Serum 5-NT activity did not change between the first and the third trimesters of pregnancy. However there is a gradual and significant increase in the mean [ +/- SD] serum sialic acid concentration with progressing pregnancy