Circadian Rhythms in Water and Solute Handling in Adults with a Spinal Cord Injury

To evaluate nocturnal urine production and circadian rhythms of renal functions (glomerular filtration, water and solute diuresis) in adults with a spinal cord injury compared to controls.

This prospective observational study was conducted in Ghent University Hospital, Belgium. Participants were asked to perform a 24h urine collection and a blood sample was taken to calculate diuresis rate and renal clearance of creatinine, free water, solutes, sodium and urea.

A total of 119 subjects were divided into patients with a spinal cord injury (n=32) and controls with (n=68) and without nocturnal polyuria (n=19). Spinal cord injured patients showed no circadian rhythms in diuresis rate or in renal clearance of creatinine, free water, solutes, sodium and urea. Controls without nocturnal polyuria reported a lower nighttime diuresis rate and lower nighttime clearance of creatinine, solutes, sodium and urea compared to daytime. Controls with nocturnal polyuria had no circadian rhythms in diuresis rate and creatinine clearance and a significant increase in nocturnal free water clearance compared to daytime.

Comparing the mechanisms underlying nocturnal urine production between patients with a spinal cord injury and controls revealed important differences. Spinal cord injured patients showed absent circadian rhythms in renal clearance of creatinine (glomerular filtration), free water (water diuresis) and solutes such as sodium and urea (solute diuresis).Future research needs to evaluate the role of patient stratification for finding the most effective and safe (combination of) treatment(s) for spinal cord injured patients with complaints or complications related to nocturnal polyuria.

The Journal of urology. 2016 Aug 06 [Epub ahead of print]

M A Denys, A Viaene, A S Goessaert, F Vanhaverbeke, P Hoebeke, A Raes, K Everaert

Department of Urology, Ghent University Hospital, Ghent, Belgium. Electronic address: ., Department of Physical medicine and orthopedic surgery, Ghent University Hospital, Ghent, Belgium., Department of Urology, Ghent University Hospital, Ghent, Belgium., Department of Urology, AZ Nikolaas, Sint-Niklaas, Belgium., Department of Urology, Ghent University Hospital, Ghent, Belgium., Department of Pediatric Nephrology, Ghent University Hospital, Ghent, Belgium., Department of Urology, Ghent University Hospital, Ghent, Belgium.