OBJECTIVETo investigate the changes of blood pressure by 24-hour ambulatory blood pressure (ABP) monitoring in children with primary nephrotic syndrome (PNS) and explore the relationship of the changes in blood pressure with rennin-angiotensin-aldosterone system (RAAS) in these children.

METHODSABP and casual blood pressure (CBP) monitoring were performed in 114 children with PNS. Plasma levels of rennin activity (PRA), angiotensin II (AngII) and aldosterone (ALD) were measured. The correlation of plasma levels of PRA, AngII and ALD with ABP was evaluated.

RESULTSOf the 114 children with PNS, 101 (88.6%) presented elevated blood pressure. Mild or severe masked hypertension was found in 45 children (39.5%). Eighty (70.2%) children showed non-dipper blood pressure. The index and load of systolic blood pressure were higher than those of diastolic blood pressure. The blood pressure index and blood pressure load during sleep were higher than those during wakefulness. The boy presented higher diastolic blood pressure index and load than girls. Decubitus blood PRA, AngII and ALD levels in children with PNS were significantly higher than normal controls. The group with elevated blood pressure presented significantly higher decubitus blood PRA, AngII and ALD levels than the group with normal blood pressure. AngII level was significantly positively correlated with the index and load of both systolic blood pressure and diastolic blood pressure.

CONCLUSIONSThe children with PNS present a high incidence of hypertension, with a large percentage of masked hypertension and non-dipper blood pressure. Systolic blood pressure increases more significantly than diastolic blood pressure. Blood pressure during sleep increases more significantly than that during wakefulness. Diastolic blood pressure increases more significantly in boys than in girls. RAAS activity is elevated and the elevated RAAS activity might increase the blood pressure mainly by AngII in children with PNS.