Potential impact of severe hydronephrosis secondary to ureteropelvic junction obstruction on pediatric blood pressure.

Background: Hydronephrosis could affect blood pressure (BP) according to published case reports and animal experiments. The impact on pediatric BP is often overlooked due to children's inherently lower BP, superior vascular elasticity and greater resistance to hypertension than adults.

Objective: This study aimed to prospectively observe the effects of hydronephrosis, secondary to ureteropelvic junction obstruction (UPJO), on pediatric BP.

Methods: Children with hydronephrosis secondary to UPJO who required pyeloplasty were categorized into five age groups: neonates, infants, toddlers, preschoolers, and school-aged children. Preoperative and postoperative systolic blood pressure (SBP), diastolic blood pressure (DBP), active renin concentration (ARC), and aldosterone concentration (AC) were compared among these age groups, followed by comparison with a control group of children without nephritis or cardiovascular conditions. The impact of severe hydronephrosis secondary to UPJO on pediatric BP and its association with the renin-angiotensin-aldosterone system (RAAS) were examined.

Results: This study enrolled 114 children with severe hydronephrosis secondary to UPJO and 153 without nephritic or cardiovascular conditions between September 2021 and June 2023. As the control group aged, SBP and DBP increased, whereas ARC and AC decreased. Overall, hydronephrosis group had higher SBP, DBP, ARC, and AC than the controls group. These differences differed between the age groups. After pyeloplasty, the postoperative BP of hydronephrosis group approximated that of the control group. Postoperative ARC levels were higher than those in the control group but were much lower than the preoperative levels. AC did not decrease significantly after surgery. The change in DBP in children with hydronephrosis before and after pyeloplasty showed a positive correlation with the change in AC.

Conclusions: Pediatric patients with severe hydronephrosis, a condition secondary to UPJO, displayed elevated BP, ARC, and AC. Following pyeloplasty, these patients noted a reduction in BP. The correlation between elevated blood pressure and the RAAS necessitates further comprehensive investigation.