Systemic hypertension and plasma renin activity in children with the hemolytic-uremic syndrome.

A group of 21 children with HUS underwent serial estimations of PRA and blood pressure. At time of administration PRA was 13.2 divided by 1.59 ng/ml/hr (mean + SE), in seven who were hypertensive the mean was 14.1 +/- 3.2 ng/ml/hr and despite the wide range PRA was considered to be elevated in 6 of this group. The 14 normotensive children had a mean PRA of 12.8 +/- 1.8 ng/ml/hr, only 1 patient having a value within the normal range. In 9 children PRA was normal once diuresis had been established (9 +/- 1.4 ng/ml/hr) and only two patients of this group were hypertensive at time of the study. PRA measured in 8 children 4 weeks after presentation was 7 +/- 1.6 ng/ml/hr, and 3 hypertensive children having a mean value of 7.5 ng/ml/hr and the 5 normotensive children a mean of 2.5 ng/ml/hr. The data indicate that activation of the renin-angiotensin system in HUS occurs irrespective of hypertension. Furthermore blood pressure levels were not correlated to the degree of hydration.