Increased urinary calcium excretion in enuretic children treated with desmopressin.

Purpose: The use of desmopressin in the treatment of primary nocturnal enuresis (PNE) is accepted and based on the fact that this drug leads to renal water reabsorption. However, recent findings have also implicated that desmopressin regulates other molecules, such as sodium and potassium. We investigate if desmopressin influences renal Ca2+ handling.

Materials And Methods: A total of 32 children with PNE were enrolled in a prospective study. Patients received a standard 30 microg desmopressin intranasally before going to bed. All patients were treated for at least 4 weeks. Desmopressin was then withdrawn and reintroduced after 2 weeks. Urine samples were collected during all 3 phases of the study. Ca2+ measurement was performed in single morning spot urines as well as in 24-hour collections. Additionally, blood was sampled for analysis of Ca2+. The Wilcoxon signed rank test was used for statistical analysis.

Results: Wet nights decreased an average of 4.75 to 1.0 per week with desmopressin treatment. While blood concentrations did not change with or without medication, urinary Ca2+ excretion was significantly higher while patients were treated with desmopressin. This significant result was the same in single spot as well as in 24-hour samples.

Conclusions: This study demonstrated the increased excretion of Ca2+ by desmopressin treatment in children with PNE. Since Ca2+ is a crucial molecule in growth and development, this finding indicates the necessity of larger followup studies concerning Ca2+ handling and growth in children on long-term desmopressin treatment.