Urinalysis in patients with neuromyelitis optica spectrum disorder

Background and purpose Increasing evidence has demonstrated that aquaporin-4 (AQP4) immunoglobulin G causes damage to the kidney in neuromyelitis optica spectrum disorder (NMOSD). However, changes in urinalysis in NMOSD have not been investigated thus far. Our objective was to evaluate the changes in urinalysis in NMOSD patients. Methods Case data were collected from 44 patients with AQP4 antibody-positive NMOSD, 53 patients with multiple sclerosis (MS) and 79 age- and sex-matched healthy controls. Analyses of early morning urine and 24-h urine samples comparing NMOSD with MS patients were conducted. Results In the acute phase, urine pH levels (P < 0.001) and urine specific gravity levels (P < 0.001) from NMOSD patients were significantly higher and lower, respectively, than for MS patients. 24-h urine sodium and 24-h urine volume from NMOSD patients were significantly higher than for MS patients (both P = 0.001). A 24-h urine volume higher than 2500 ml (odds ratio 11.7, 95% confidence interval 1.863-73.066) and a 24-h urine sodium higher than 200 mmol (odds ratio 16.0, 95% confidence interval 2.122-120.648) are more likely to occur in NMOSD patients in the acute phase than in MS patients. Conclusions The urinalysis results were significantly different between NMOSD patients and MS patients. The pathophysiological changes in AQP4 antibody-positive NMOSD patients were not limited to the central nervous system.