24-hour blood pressure monitoring in children and adolescents after recovery from hemolytic uremic syndrome.

24-hour blood pressure monitoring is a valuable method for the diagnosis of arterial hypertension as well as for assessment of the diurnal rhythm of the arterial blood pressure (BP). The nocturnal decrease of blood pressure ("dipping") may be attenuated or abolished in children with advanced renal failure and glomerular diseases. Arterial hypertension is a longlasting problem in children who had recovered from hemolytic uremic syndrome (HUS). We therefore performed BP monitoring in 11 children and adolescents (age 1.3 to 18.8 years, 6 males, 5 females) after HUS using a portable oscillometric device (SpaceLabs 90207). Six of the subjects had a normal renal function (group A). The other 5 patients had impaired renal function with a glomerular filtration rate <60 ml/min/1.73 m2 (group B). Nocturnal dipping was calculated as nocturnal mean blood pressure minus diurnal mean blood pressure given in per cent of diurnal mean blood pressure. Two of the patients in group A had diurnal mean BP above the 95th percentile of the German collaboration study, but none of the group was hypertensive during the night, and nocturnal dipping was 13.6% (9.7-15.5%, median and range) for systolic BP and 23.7% (15.5-29.9%) for diastolic BP which is very similar to healthy children. All of the patients had a normal diurnal BP rhythm. From patients of group B, 4 had elevated diurnal mean BP and also 4 were hypertensive during the night. Nocturnal dipping was 1.4% (0.7-4.1%) for systolic and 6.8% (0-10.7%) for diastolic BP which is clearly attenuated compared to group A. We therefore conclude that arterial hypertension is more common in patients after HUS if they have impaired renal function, and diurnal rhythm of arterial blood pressure is attenuated in these patients. However, nocturnal dipping of blood pressure is not disturbed in children after HUS without renal insufficiency, even if they were hypertensive.