Failure of platelet angiotensin II binding to predict pregnancy-induced hypertension

To determine whether measurement of platelet angiotensin II binding at 20 weeks' gestation identifies women destined to develop pregnancy-induced hypertension.

Over a 2-year period, we recruited 325 unselected, normotensive primigravidas from the hospital antenatal department after their routine 20-week scan appointments. Each woman had a singleton pregnancy, was normotensive at the time of entry into the study, and had an unremarkable medical history. Ninety-three nonpregnant women were recruited from the hospital staff for comparison. Platelet angiotensin II binding was measured in all participants. After delivery, the case notes were screened to determine pregnancy outcome.

Two hundred sixty-seven women remained normotensive to delivery, 30 developed nonproteinuric pregnancy-induced hypertension, 23 developed proteinuric pregnancy-induced hypertension, four had transient hypertension, and one was diagnosed subsequently as having essential hypertension. The median platelet angiotensin II binding for the nonpregnant subjects was 15.7 fmol/10(9) platelets, which differed significantly from the value for normotensive pregnant subjects (4.8 fmol/10(9) platelets, P < .001) and from the value for those who developed either nonproteinuric pregnancy-induced hypertension (4.95 fmol/10(9) platelets) or proteinuric pregnancy-induced hypertension (7.2 fmol/10(9) platelets, P < .001). There was no significant difference between pregnant women who remained normotensive and those who developed nonproteinuric or proteinuric pregnancy-induced hypertension.

Measurement of angiotensin II binding in the second trimester has no value as a screening test for nonproteinuric or proteinuric pregnancy-induced hypertension.