Daytime water restriction effective in nocturia

Researchers from Japan say that some men with nocturia should be advised to restrict their fluid intake during the day and not just at night.

The team found that, in men whose 24-hour urine production was greater than 30 mL/kg of bodyweight, water intake restriction throughout the day led to significant reductions in nocturia frequency and nocturnal urine volume.

Lead researcher Mitsuru Tani (Nara Medical University School of Medicine) and colleagues say therefore, in these patients, “water-intake guidance might be considered effective and safe as a lifestyle therapy, and should be recommended to patients before they undergo drug treatment.”

The team studied 65 male patients with nocturia as a result of nocturnal polyuria and a 24-hour urine production of more than 30 mL/kg of bodyweight. The men were instructed to reduce their water intake to produce a 24-hour urine production lower than this threshold.

One month later, all patients had significantly decreased 24-hour urine production, from a mean of 37.1 mL/kg at baseline to 26.8 mL/kg. There was also a significant decrease in nocturnal urine volume, from 910 mL to 610 mL, and in nocturia frequency, from 4.1 to 3.1 episodes a night. Overall, 44 (67%) men experienced an improvement in nocturia frequency by at least one fewer episode per night, the definition of treatment success.

Interestingly, the researchers found that the change in daytime drinking volume, but not the change in evening drinking volume, was independently associated with therapeutic efficacy of the intervention.

The team explains that conventional water intake guidance is focused primarily on excessive water intake at night as it is thought that this leads to nocturnal polyuria.

They say that their findings indicate that “it is important that water restriction be carried out not only in the evening but also during the daytime.”

They conclude in the International Journal of Urology that studies must be carried out in a clinical setting to confirm their results: “Our present findings therefore warrant a future prospective study to establish a therapy for nocturia using more appropriate intervention procedures for [nocturnal polyuria].”

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