Rapid communicationLow serum vitamin D levels and anti-N-methyl-d-aspartate receptor encephalitis: A case-control study

•Serum 25(OH)D levels were reduced in anti-NMDAR encephalitis patients.•25(OH)D levels were lower in female subgroup than that in male subgroup.•25(OH)D levels were lower in severe impairment subgroup than that in mild symptoms subgroup.•25(OH)D levels were lower in those with limited treatment than those with favorable treatment.•Serum 25(OH)D levels were significantly associated with age, disease severity.

BackgroundLow vitamin D levels are associated with autoimmunity, but the relationship with anti-N-Methyl-d-aspartate receptor (anti-NMDAR) encephalitis is unknown.Methods25(OH) D levels and clinical and cerebrospinal fluid parameters were evaluated in 30 patients with anti-NMDAR encephalitis and compared with 90 age-, sex-, and season-matched healthy controls.Results25(OH)D levels were lower in patients with anti-NMDAR encephalitis compared to controls (43.89 ± 17.91 vs 64.24 ± 24.38 nmol/L, p < 0.001), especially for females (vs males, p = 0.008), aged ≤30 years (vs > 30 years, p = 0.002), severe impairment (mRS ≥ 5) (vs mRS < 5, p = 0.018), and limited treatment responses (vs favorable treatment, p = 0.02). Serum 25(OH)D levels were associated with age (r = 0.393, p = 0.032), and mRS (r = −0.417, p = 0.022).ConclusionsOur data showed that serum 25(OH)D levels were reduced in patients with anti-NMDAR encephalitis.