The association between serum sodium levels and tuberculous meningitis compared to viral and bacterial meningitis: Multicenter retrospective cohort study

Abstract We evaluated the association between hyponatremia and tuberculous meningitis (TBM) in hopes of providing additional information for the differential diagnosis of TBM from other types of infectious meningitis, especially from viral meningitis (VM). Cross-sectional and longitudinal data involving 5,026 participants more than 18 years of age were analyzed in the total population and the propensity-matched population. The initial and lowest sodium levels and longitudinal changes in TBM, VM, and bacterial meningitis (BM) patients were compared. The initial serum sodium levels were significantly lower in the TBM patients than in the VM and BM patients (136.9 ± 5.9 vs. 139.0 ± 3.1, p < 0.001 for TBM vs. VM, and 138.3 ± 4.7 mmol/L and p < 0.001 for TBM vs. BM) and it dropped significantly more steeply to lower levels in both the TBM and BM patients compared to the VM patients. Consequently, the lowest serum sodium levels were in the order of the TBM < BM < VM patients, which were also statistically significant in all subgroups. (131.8 ± 6.4, 133.1 ± 5.1, 137.4 ± 3.7, respectively, p < 0.001). The participants with lower serum sodium levels were more likely to have a diagnosis of TBM rather than VM, and this association was more pronounced for the lowest sodium levels than the initial sodium levels (OR 8.4 (95% CI: 4.5–15.8, p < 0.001)). The baseline and longitudinal evaluation of serum sodium levels can provide supportive information for the differential diagnosis of TBM from VM or BM.