SAN FRANCISCO—Risk factors for nocturnal polyuria, including underlying comorbidities, may be underreported in standard history taking, according to researchers presenting at the American Urological Association’s 2018 annual meeting.

Harjot Singh, BS, of SUNY Downstate College of Medicine in Brooklyn, New York, and colleagues assessed the prevalence of potential risk factors for nocturnal polyuria in 524 patients (338 male and 186 female, aged 12 and older) with lower urinary tract symptoms (LUTS). The team defined 2 groups using the nocturnal polyuria index (NPi), calculated as the nocturnal urine volume divided by 24-hour urine volume. Nocturnal polyuria (NP+) was distinguished from normal nocturnal urine production (NP-) at an NPi cutoff of 0.33 (nightly urine volume in excess of 33% of 24-hour urine volume).

Of the 145 NP+ patients (mean age 71.5 years), 66% were male and 34% were female. Of 379 NP- patients (mean age 60 years), 64% were males and 36% were females. On average, the NP+ and NP- groups had 11.8 vs 10.6 voids daily, respectively, and 3.5 vs 1.3 voids nightly, respectively.

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Only age, number of voids per 24 hours, and nocturia episodes strongly correlated with nocturnal polyuria, Dr Singh’s team reported. Overactive bladder was overrepresented relative to the general population (19% vs 10.7%). Some nocturnal polyuria risk factors were underreported compared with the general population, such as pedal edema and sleep apnea. With regard to medication classes, only alpha1-blockers were significantly associated with nocturnal polyuria.

“We were surprised to see a lack of correlation between nocturnal polyuria and its known causes, such as sleep apnea and pedal edema,” Singh told Renal & Urology News. “We also did not identify any new risk factors for nocturnal polyuria, likely due to the small sample size. The data suggest that risk factors for nocturnal polyuria may be underreported in standard history taking. The-24 hour frequency volume chart remains the gold standard for diagnosing nocturnal polyuria.”

The team urged future studies with larger study populations and separate analyses of men vs women. Detailed medication assessment is also warranted.

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Singh H, Weiss J, Blaivas J, et al. Risk factors for nocturnal polyuria. Presented at the American Urological Association 2018 annual meeting in San Francisco, May 18–21. Poster MP79-15.