Hypertension in pregnancy: the incidence of underlying renal disease and essential hypertension.

The objective of this study was to ascertain the likelihood of underlying renal disease or essential hypertension in women diagnosed antepartum as having pre-eclampsia. One hundred eighty-six women (antepartum diagnosis of pre-eclampsia in 87 women and gestational hypertension, also known as "mild pre-eclampsia" by other definitions, in 99 women) in whom no underlying disorder was apparent during pregnancy or the early puerperium were entered into the study. Women were reviewed between 3 and 60 months postpartum. All patients were assessed by measurement of blood pressure, urinalysis, and phase-contrast urine microscopy, and those with pre-eclampsia also had plasma urea, electrolyte, and creatinine concentrations determined and underwent renal imaging with either intravenous pyelography or ultrasound. The kidneys were also imaged in the gestational hypertension group if there was any clinical suspicion of underlying renal disease on review. Essential hypertension was diagnosed if systolic blood pressure was higher than 140 mm Hg and/or diastolic blood pressure was higher than 90 mm Hg after 3 months postpartum and the results of other investigations were normal. Renal disease was diagnosed in the presence of abnormal findings on urinalysis, urine microscopy, or renal imaging, or by elevated plasma creatinine concentration. Seven (8%) of the 87 women with pre-eclampsia had underlying disease (essential hypertension, five patients; renal disease, two patients [one with reflux nephropathy and one with medullary sponge kidney]), as did 16 (16%) of the 99 women with gestational hypertension (essential hypertension, 14 patients (14%); renal disease, two patients (2%) [one with medullary sponge kidney and one with thin basement membrane disease]).(ABSTRACT TRUNCATED AT 250 WORDS)