Is Urine Production Rate at Night Uniform or Phasic in Patients Treated for Clinically Significant Nocturia?

A recent study from the European Urology Focus journal, “Differential Nocturnal Diuresis Rates Among Patients With and Without Nocturnal Polyuria Syndrome” the Veterans Affairs Health System analyzed frequency-volume charts of adult males with two or more nocturnal voids. After excluding patients with diuretic use, obstructive sleep apnea, chronic kidney disease, diabetes insipidus or edema, 130 subjects were included.  

The group was split those with nocturnal polyuria (NP) and those without NP. The study sought to determine if the urine production rate at night was uniform or phasic in a patient treated for clinically significant nocturia.  

The night was split into the early part of the night, which was the diuresis rate during the first uninterrupted period (FUSP), and the late part of the night, which was the diuresis rate of the sleeping hours after the first uninterrupted awaking and the time when the individual awakens with the intention of rising. 

The result showed that those with NP (and no identifiable contributory comorbidities, medication, behavioral patterns, etc.) had different rates of urine production in the early part of the night compared to the latter part of the night.  There was a higher nocturnal diuresis rate that occurs up to the first awakening and then a drop of the diuresis rate after the first awakening. These findings were only seen in the NP population, as the rates of diuresis were fairly constant in the non-NP-patients.  

So, like many well-done poignant studies, there are no other questions that we need to answer.  Do the different rates of diuresis in this NP population reflect differences in sleep architecture in the early part of the night vs the sleep architecture in the later part of the night? Will the diuresis rate during the FUSP alone (an easy measure to obtain with recording the volume of a single void and the time with which this void occurred) allow us to accurately predict the presence of NP?  Will these data help determine response to antidiuretic medication? Though we now may have more questions, this work helps us understand nocturia and NP more clearly. Job well done.

Written by: Benjamin Brucker, MD 

Pelvic Health Weekly Newsletter