Cerebrospinal fluid uric acid levels associated with disease severity in patients with anti-N-methyl-d-aspartate receptor encephalitis.

INTRODUCTION: Uric acid (UA) is an important natural antioxidant and strong peroxynitrite scavenger, but little is known about central nervous system (CNS) levels of UA in patients with anti-N-methyl-d-aspartate receptor encephalitis (NMDARE).

METHODS: Cerebrospinal fluid (CSF) and serum levels of UA were determined in 72 patients with anti-NMDARE and 111 controls with non-inflammatory neurological diseases (NINDs). Serum UA levels were also evaluated in 132 healthy controls (HCs). CSF neuron-specific enolase (NSE) and blood-brain barrier (BBB) index were evaluated in patients with anti-NMDARE. The association of CSF UA levels with anti-NMDARE and its clinical parameters were evaluated in the patients.

RESULTS: CSF UA levels were lower in patients with anti-NMDARE than in patients with NINDs, especially in patients with severe impairments (modified Rankin Scale [mRS] scores >3 vs. ≤ 3, p = 0.006). Furthermore, serum UA levels in patients with anti-NMDARE were significantly lower than in patients with NINDs and HCs. CSF UA levels were significantly associated with mRS scores, and serum UA levels in patients with anti-NMDARE. Furthermore, CSF/serum UA ratio was significantly associated with BBB index.

CONCLUSIONS: CSF UA levels associated with disease severity and serum UA levels in patients with anti-NMDARE. And CSF/serum UA ratio correlated with BBB index, indicating that CSF and serum UA levels change similarly with BBB permeability in anti-NMDARE patients.