Investigation of biochemical factors related to non-bothersome nocturnal urination.

We investigated the factors related to nocturnal urination that was not considered bothersome by comparing various parameters between subjects who felt nocturnal urination as bothersome and those who did not. A total of 94 persons (50 males and 44 females) were enrolled. They urinated >or= once per night. Each subject's perception of nocturnal urination was examined, and the subjects were divided into a bothersome group and a non-bothersome group. Blood biochemical data and urinary condition were compared between the two groups and various subgroups. There were 60 subjects (56 +/- 17 years old) in the non-bothersome group, and 34 subjects (57 +/- 17 years old) in the bothersome group. The serum melatonin level was significantly lower and the total score of the International Prostatic Symptom Score questionnaire (IPSS) and the quality of life (QOL) score were significantly higher in the bothersome group than in the non-bothersome group. Among 50 subjects with nocturnal urination >or= twice per night, the serum melatonin level was also significantly lower and the QOL score was significantly higher in the bothersome group than in the non-bothersome group. In conclusion, nocturnal urination might be not considered bothersome when subjects maintain sufficient levels of melatonin.