Solute and Water Excretion Patterns in Patients with Nocturnal Polyuria

Abstract

Background and Aims: Nocturia is a highly prevalent and troublesome lower urinary tract symptom, with 28-36% of adults usually voiding at least twice nightly. For many patients, nocturia arises from the presence of nocturnal polyuria (NP), usually defined as being present when more than 33% of the total 24-hour urine output occurs at night while the total 24-hour urine output remains normal. We report results of an innovative evaluation in a clinical sample of 29 nocturia patients found to have NP during evaluation of their nocturia symptoms. Methods: Patients with nocturia collected 24-hour urine specimens split into two containers, one of which was collected during the daytime, the second collected during the nighttime. We analyzed patterns of solute and water excretion, comparing daytime to nighttime collections. Results: Overall the group demonstrated remarkably abnormal patterns of solute and water excretion, with the rate of urine production dramatically greater at night (mean 118 mL/hr) than during the day (mean 56 mL/hr; p