Urinary risk factors for calcium oxalate urolithiasis in children with monosymptomatic enuresis

Introduction: A disturbed calcium-phosphate balance is an important issue for kidney stone formation in nephrolithiasis. Hypercalciuria (HC) has been proposed as an essential etiology of monosymptomatic nocturnal enuresis (MNE). Objectives: We may suspect that patients with MNE may be at risk of stone formation hence the objective of this paper was to assess the risk in MNE children using Bonn Risk Index (BRI). Patients and Methods: The urinary work-up of 204 children (83 with MNE and 121 controls) included urinary calcium (Ca), magnesium (Mg) and sodium (Na) excretion, Ca/creatinine ratio, BRI, ionized calcium (Ca2+), Mg/creatinine and Ca/citrate ratios, urinary citrates and oxalates (Ox). Results: Ca/creatinine and Mg/creat ratios were higher in the MNE group. There were no differences in Mg and Ca amount in urine and Mg/Ca ratio between MNE and the reference group. Both groups differed in Mg and Ca excretion per kg of body mass. MNE children differed from controls regarding BRI, Ox and urinary Ca2+. No differences in urinary citrate excretion nor Ca/citrate ratio between MNE and the controls were found. Correlations between factors important in the crystallization process in MNE children were recorded. Conclusion: MNE patients may be at risk of oxalate nephrolithiasis. Further studies to assess the role of the BRI and Ca/citrate ratio in predicting stone formation in MNE children are needed.