Melatonin rhythm in children with enuresis

OBJECTIVE: To study the circadian rhythm of melatonin in children with enuresis. PATIENTS AND METHODS: Twenty-five children, divided into two groups (enuretic patients and controls) were assessed; salivary samples were collected to measure melatonin by radioimmunoassay using commercial kits. Friedman two-way anova and Wilcoxon tests were used to assess the circadian rhythm of melatonin, and anova with between-patient factors and Mann-Whitney tests to compare melatonin values and groups. RESULTS: Both groups had statistically significant differences in melatonin concentration during the 24-h period (both P < 0.001), with a circadian rhythm; the highest values were always at approximately 04.00 hours. There were no significant differences overall in melatonin values between cases and controls, but patients had lower peak values than controls at 04.00 hours, and higher melatonin levels at 24.00 hours, but with no significant differences. CONCLUSION: There was some evidence for minor disturbances in the circadian rhythm of melatonin as a cause of enuresis, but the rhythm was not grossly disrupted.