PURPOSE OF REVIEW: To review the published literature within the last 18 months that comment on the causes of nocturia, varying with age. The causes are categorized into organized subsets: nocturnal polyuria, storage or reduced bladder capacity, 24-h polyuria, and sleep-associated nocturia. RECENT FINDINGS: Prevalence of nocturia is high, but has been reported at varying rates in the epidemiologic studies. Similarly, reported incidence has a high rate of variability. Nocturia causes were associated with nocturnal polyuria, bladder storage issues, metabolic syndrome, abnormal bowel habits, obesity, Parkinson's disease, global polyuria, insomnia, sleep disturbances, heart failure, anxiety, and depression. Although age was commented on in many articles, it was never the primary examined variable. SUMMARY: There is a lack of standardization in definition and classification of the causes of nocturia. Confounding variables included a lack of use of a standard definition of nocturia, identifying nocturia at its true onset, and a fundamental underutilization of frequency volume charts to identify patients with nocturia. The confounding variables make it difficult to compare studies. Thus, the strength of conclusion on cause will be better defined when standards are set controlling definition, identification, and diagnosis.
