[Birth weight and hypertension (HT) in children with reflux nephropathy (RN)]

Abstract

Low birth weight (bw) has been related to low nephron number and hypertension. Age is an important predictor of developing hypertension in patients with reflux nephropathy (RN). The aim of the study was to assess the relationships between birth weight and blood pressure in children with RN. We investigated 150 patients in mean age 9 +/- 3.3 years with vesicoureteral reflux. In all patients we collected birth weight, we also performed renal scintigraphy (DMSA) and 24-hour ambulatory blood pressure monitoring (ABPM). Standard deviation score body mass index (BMI SDS) was calculated. In ABPM mean value of systolic and diastolic blood pressure (sBP, dBP), blood pressure load during 24 hour and during day and nighttime (LsBP, LdBP) were analyzed. As objective parameters of BP in children in different age and hight, systolic and diastolic BP indices (sBPI, dBPI) were calculated.

Results: In analyzed group of children mean bw was 3340 +/- 587 g (from 1300 to 5000 g); in 10 children bw was <2500 g. In 20 children (13%), in 3 with bw <2500 g (30%) and in 17 (12.5%) with normal bw hypertension was diagnosed. The mean age and BMI SDS were lower in children with bw < 2500 g and HT than in children with normal bw and HT (8.2 vs 9.9 years and median -0.53 vs -0.22 respectively). In children with HT mean bw was 3247 +/- 666 g and in children without HT 3293 +/- 461 g (NS). No statistically significant difference was found depends of grades of renal damage in DMSA scan for bw. The negative correlation was found between bw and sBPI, LsBP during 24h and sBPI i LsBP during nighttime (p<0.05 r=-20, p<0.05 r=-19; p<0.05 r=-16, p<0.01 r=-26 respectively). No correlation was found between bw and dBP values.

Conclusion: In children with RN low bw may be a potential risk factor for developing hypertension independent of severity of renal scarring.