Nocturnal Polyuria: What We Need to Know in 2015

Nocturnal polyuria (NP) is a prevalent yet underdiagnosed condition due to a lack of complete understanding of NP and its precise definition. The International Continence Society (ICS) defines NP as the production of an abnormally large volume of urine during sleep with normal 24-h urine production. The NUP90 definition was shown to have more discriminative power and be a stronger predictor of nocturia than the current ICS definition resulting in debate. The etiology of NP is multifactorial. Two etiologies of primary NP include increased free water clearance and high solute concentration. Obstructive sleep apnea (OSA) is also associated with NP with severity of symptoms increasing with severity of apnea. The primary treatment for NP is desmopressin, which works by decreasing urine production. Recently, a meta-analysis showed no difference between low versus high doses, suggesting that starting with a 50 μg dose may decrease the risk of side effects without compromising efficacy.