Purpose: We evaluated the incidence of hypercalciuria, defined as urinary calcium-to-creatinine ratio greater than 0.21 mg/mg, in children with nocturnal enuresis, and the association with concurrent values of diuresis and osmolar excretion.
Materials and methods: A total of 550 children admitted to a tertiary university center were included in the study. A 24-hour urine collection was performed in 8 sampling periods for measurement of calcium excretion, osmolality and diuresis.
Results: Of the children with nocturnal enuresis 12% had 24-hour hypercalciuria. Up to 29% of the timed urine samples exhibited hypercalciuria. There was a significant correlation between calcium excretion and nocturnal diuresis volume (polyuria), low urinary osmolality, and increased sodium and osmolar excretion of nighttime urine samples (all p <0.001).
Conclusions: Patients referred to a tertiary enuresis center have a high incidence of hypercalciuria. However, the significant correlation between hypercalciuria and osmolar excretion and diuresis suggests that it is a comorbid factor rather than a primary pathogenic factor. As such, we cannot confirm the data from Italian studies relating nocturnal enuresis to primary hypercalciuria, and suggest instead an association with nutritional intake.