Snoring as a cause of nocturia in men with lower urinary tract symptoms

A systematic evaluation of factors associated with nocturia--the population-based FINNO study

In a case-control study with prevalence sampling, the authors explored the correlates for nocturia and their population-level impact. In 2003–2004, questionnaires were mailed to 6,000 subjects (aged 18–79 years) randomly identified from the Finnish Population Register (62.4% participated; 53.7% were female). Questionnaires contained items on medical conditions, medications, lifestyle, sociodemographic and reproductive factors, urinary symptoms, and snoring. Nocturia was defined as ≥2 voids/night. In age-adjusted analyses, factors associated with nocturia were entered into a multivariate model. Backward elimination was used to select variables for the final model, with adjustment for confounding. Although numerous correlates were identified, none affected ≥50% of nocturia cases of both sexes. The factors with the greatest impact at the population level were (urinary) urgency (attributable number/1,000 subjects (AN) = 24), benign prostatic hyperplasia (AN = 19), and snoring (AN = 16) for men and overweight and obesity (AN = 40), urgency (AN = 24), and snoring (AN = 17) for women. Moreover, correlates included prostate cancer and antidepressant use for men, coronary artery disease and diabetes for women, and restless legs syndrome and obesity for both sexes. Although several correlates were identified, none accounted for a substantial proportion of the population burden, highlighting the multifactorial etiology of nocturia.

Multifactorial nature of male nocturia

OBJECTIVES

To conduct a prospective study to determine the causes of nocturia in men.

METHODS

The study included 41 male patients (mean age 72.5 years) bothered by nocturia (two or more micturitions per night). Eleven asymptomatic young men (mean age 28.4 years) were enrolled as a control group. All completed a 3-day voiding diary. Daytime and nighttime urine samples were collected to determine osmolality and sodium and potassium levels. Urodynamic studies were performed for all patients with nocturia to evaluate for bladder outlet obstruction using the International Continence Society definition. Polysomnography was performed on selected patients to detect sleep apnea.

RESULTS

The average nighttime voiding frequency was 3.9 in the patients with nocturia. Nocturnal polyuria (NP) was found in 34 (82.9%) of 41 patients. In these patients, the nighttime urinary sodium excretion was significantly greater than the daytime excretion, with lower nighttime urine osmolality. In contrast, nighttime and daytime sodium excretion was not significantly different in patients without NP, and greater nighttime urine osmolality was noted in the patients without NP and the control group. Of the 41 patients, 24 (58.5%) had a small nocturnal bladder capacity, with detrusor overactivity in 14 of 24 patients. Eighteen patients (43.9%) had both NP and a small nocturnal bladder capacity. Another 18 patients had bladder outlet obstruction and NP. Two patients had sleep apnea.

CONCLUSIONS

Our observations have shown that a significant contributor to male nocturia is NP, which results from a disordered diurnal rhythm of sodium excretion and other unknown factors causing nocturnal urinary dilution. However, male nocturia can also be secondary to a combination of factors. Detailed workup is necessary to elucidate all causes.