Nocturnal polyuria in patients with lower urinary tract symptoms and response to alpha-blocker therapy

To determine the prevalence of nocturnal polyuria (NP, defined as a nocturnal urine fraction exceeding one third of the daily urine output in elderly men) in patients with lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH) and clinical responsiveness to alpha-blocker therapy.

Outpatients with LUTS suggestive of BPH were included. Patients filled out the International Prostate Symptom Score questionnaire and a 7-day voiding diary, and urinalysis, prostate-specific antigen measurement, uroflowmetry, and ultrasonography were performed. Patients with NP were given alpha-blocker therapy (tamsulosin 0.4 mg/day) for 6 weeks and then re-evaluated for NP and urinary symptoms.

A total of 58 outpatients were included in the study. Of these, 95% had NP. The mean frequency of nocturia was 2.73 +/- 1.44 per day. A significant correlation was found between NP and the duration of LUTS (r = 0.393, P = 0.035) and the amount of water intake within 3 hours before sleep (r = 0.731, P = 0.001). Of the patients with NP, 20 were given alpha-blocker therapy. After therapy, the peak urinary flow rate had increased significantly, but NP remained unchanged in 75% of the patients.

NP is a common symptom accompanying LUTS suggestive of BPH. Our results showed that it is significantly related to the duration of LUTS and amount of water intake before sleep. NP cannot be treated with alpha-blocker therapy, although there is improvement in LUTS suggestive of BPH.