Lactic acid levels in cerebrospinal fluid from patients with systemic lupus erythematosus.

Cerebrospinal fluid (CSF) samples from 22 patients with systemic lupus erythematosus (SLE) and 20 samples from normal controls were studied for lactic acid levels. Ten samples were obtained from SLE patients with active central nervous system (CNS) involvement and 12 from SLE patients with inactive CNS disease. The mean CSF lactic acid level in patients with SLE was 17.24 +/- 1.25 mg/dl (range 31-10.2 mg/dl) which was not statistically different to the normal control mean of 14.75 +/- 0.9 mg/dl (range 9-28 mg/dl). Thus, lactic acid levels in active or inactive CNS disease of SLE appear to be normal. Due to the fact that lactic acid levels are elevated in the CSF of patients with bacterial meningitis, lactic acid levels can be of potential value in the differentiation between bacterial meningitis and CNS involvement of SLE.