Data shift thinking on nocturia’s causes, treatment

November 20, 2018

 Waking up at night to urinate is by far the most bothersome lower urinary tract symptom. 

Dr. Badlani, a Urology Times editorial consultant, is professor of urology at Wake Forest Baptist Medical Center, Winston-Salem, NC.

Waking up at night to urinate is by far the most bothersome lower urinary tract symptom. It is clear now that nocturia has a distinct pathophysiology from daytime urinary frequency with some overlapping causes. However, its impact on quality of life and health is profound.

It disproportionately affects the elderly, physically disabled, and those overweight. Although the incidence in women may be slightly higher (almost 30% in a recent study using the NHANES database [see article "Nearly 30% of U.S. women report nocturia"), it is present in men as well. During my early years in urology, nocturia was the index that determined if an older man underwent TURP. Today it is clear that urologic causes are way down the list of etiologies.

Fluid shift from the lower extremities resulting in higher urine output is a common cause that can be improved with leg elevation in the evening and restricting intake 2 hours prior to bedtime. Additionally, if the patient takes a diuretic in the morning, changing the time to late afternoon may reduce output at night. Thus, a frequency and volume chart at night compared to the day is by far the most useful diagnostic tool.

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A medical history is critical, including the presence of sleep apnea, cardiopulmonary conditions, recurrent lower extremity edema, and sleep-cycle disturbance. Drugs such as diuretics and lithium can cause excessive output.

One might be surprised that obstetrical history was found to have no association with nocturia in the NHANES study, since urinary symptoms are affected by the obstetrical history. The postulate here is the significant time interval between the obstetrical event and the age where nocturia is a bother leads to a recall bias.

Lack of effective medical therapy has frustrated many patients and physicians, but oral desmopressin was used by <5% in one study (World J Urol Oct. 4, 2018 [Epub ahead of print]) for fear of electrolyte imbalance, particularly in the elderly. A newer nasal spray formulation has a shorter half-life and is perhaps safer.

Reduced bladder capacity and incomplete emptying in men, particularly due to obstruction, is easier to treat, whereas medical causes such as sleep apnea, diabetes, and renal disease require a significant effort on the patient’s part.

Catastrophic events such as falls and fractures while getting up at night are a major burden in the elderly, and in the REDUCE trial sub-analysis, “Nocturia was associated with increased mortality risk (hazard ratio [HR] = 1.72; 95% CI 1.15-2.55) independent from demographics and medical comorbidities” (Prostate Cancer Prostatic Dis Sept. 13, 2018 [Epub ahead of print]).

Waking up at night can be frustrating for many patients, especially if it takes a while to drift back into dreamland, which leaves them tired and sleep-deprived the next day. To paraphrase singer Alison Krauss: I don’t look for bliss, just contentment of a good night’s sleep!