Diagnostic utility of heat stable alkaline phosphatase in hypertensive disorders of pregnancy.

BACKGROUND Hypertensive disorders in pregnancy (HDP) complicate 3-10% of all pregnancies. Though there are several biochemical parameters which aid in predicting hypertension of pregnancy, human placental alkaline phosphatase (PLAP), synthesized in placenta during pregnancy by placental syncytiotrophoblast, assumes diagnostic relevance. The purpose of this study was to compare the total alkaline phosphatase (ALP) and heat stable placental alkaline phosphatase (PLAP) levels in the serum of normotensive and hypertensive disorders of pregnancy and to evaluate the clinical utility of ALP and PLAP as a reliable, sensitive, specific and economical biochemical marker of HDP. MATERIALS AND METHODS This was a case control study, carried out on pregnant women with hypertension, of south Indian population. Study included pregnant women, 60 patients with hypertension and 60 controls. Biochemical assays were carried out by the IFCC approved procedures based on spectrophotometric method and using fully automated random access chemistry analyser. Data was compared by using student t-test. ROC was drawn to find out optimum cut off for ALP, PLAP and PLAP/ALP ratio in HDP. Pearson's correlation was performed to ascertain the association among markers. RESULTS Serum total ALP, PLAP and PLAP/ALP ratio levels were significantly higher in hypertensive pregnant women when compared to controls (p<0.05). There was significant correlation among ALP, PLAP and DBP. ROC analysis of ALP (169.5), PLAP (69) and PLAP/ALP (0.44) ratios showed optimum cut-offs in diagnosis of hypertension in pregnancy. CONCLUSION Serum heat stable ALP isoenzyme and PLAP/ALP ratio could be useful adjuvant markers in diagnosis of HDP in association with other relevant and economically viable biochemical tests.