Association Between Multicystic Dysplastic Kidney and the Local Renin-Angiotensin-Aldosterone System: A Pilot Study of a New Biomarker.

Aim: To examine the relationship between children with multicystic dysplastic kidney (MCDK) that persists or spontaneously regresses over time and local renin-angiotensin-aldosterone system (RAAS) activity in children.

Methods: We conducted a multicentre, cross-sectional study of patients who were diagnosed with unilateral MCDK or a solitary kidney. The controls were age- and sex-matched children who underwent evaluation for short stature without any clinical kidney symptoms. We evaluated urinary angiotensinogen (AGT) as a biomarker of local RAAS activity, which acts specifically within the kidneys and differs from systemic RAAS.

Results: We included 52 children who were divided into the following four groups: 11 children with residual MCDK (MCDK persisted), 11 with regressed MCDK (MCDK spontaneously regressed), 12 with a solitary kidney and 18 were controls. Hypertension was identified in six patients, all of whom were in the residual or regressed MCDK groups. The urinary AGT/creatinine ratio was significantly higher in children in the residual MCDK group than in those in the regressed MCDK, solitary and control groups (p = 0.02, p < 0.01, p < 0.01, respectively). A logistic regression model showed that the only significant independent factor for regression of MCDK was urinary AGT/creatinine (odds ratio: 16.0, p < 0.01).

Conclusion: Our data suggest that local RAAS activation could be associated with persistence of MCDK, but causality cannot be inferred because of the cross-sectional study design. Whether RAAS activation in residual MCDK is involved in the pathogenesis of MCDK or AGT is secreted from the MCDK kidney itself remains unknown.