The Effect on the Kidney in Patients With Anti-N-methyl D-aspartate Receptor Antibody Encephalitis

Objectives: The function of the N-methyl-D-aspartate receptor (NMDAR) in the kidney has been studied. However, the effect on the kidney from anti-NAMDAR antibody encephalitis has not been investigated thus far. Methods: Case data were collected from 82 patients with anti-NMDAR antibody encephalitis and 166 age- and sex-matched healthy controls (HCs). Clinical characteristics, urinalysis [including urine pH and urine specific gravity (SG)], serum creatinine (Scr), and estimated glomerular filtration rate (eGFR) based on Cr levels were evaluated. Results: At initial admission, urine pH levels and urine SG levels in anti-NMDAR antibody encephalitis patients were significantly higher and lower, respectively, than HCs (both p < 0.001). There were no significant differences in Scr and eGFR between anti-NMDAR antibody encephalitis patients and HCs. Urine pH levels in patients with anti-NMDAR antibody <1:32 were significantly lower than those in patients with anti-NMDAR antibody ≥1:32 (p = 0.029). Urine pH levels were significantly lower (p = 0.004) and urine SG levels were significantly higher (p = 0.027) in a follow-up evaluation 3 months after treatment. Conclusions: The changes in urinalysis occur in patients with anti-NMDAR antibody encephalitis. The pathophysiological changes in anti-NMDAR antibody encephalitis were not limited to the CNS.