Hyponatremia and treatment outcomes in patients with tuberculosis

<bold>Background:</bold> Hyponatremia may be present in patients with TB, but its clinical significance is not well understood. This study aimed to identify risk factors for the occurrence of hyponatremia at diagnosis of tuberculosis (TB) and the impact of hyponatremia on the outcome of TB treatment. <bold>Methods:</bold> This is a single-center, retrospective study. Patients diagnosed and treated for TB at Chonnam National University Hospital from 2010 to 2017 who had baseline sodium measured were enrolled. Hyponatremia was defined as a serum sodium level of 135.o mmol/L or less at the time of TB diagnosis. <bold>Results:</bold> A total of 759 TB patients were enrolled in the study, of which 176 (23.2%) were in the hyponatremia group. The serum sodium level of the hyponatremia group was significantly lower than that of the non-hyponatremia group (mean 132.5 vs. 139.3 mmol/L; P < 0.000). Diabetes, hypertension, and chronic kidney disease were significantly more common in the hyponatremia group. The risk factors for hyponatremia were diabetes, hypertension and high C-reactive protein level in multivariate logistic regression analysis. In multivariate analysis by logistic regression analysis, hypernatremia was associated with unfavorable outcome of TB treatment (odds ratio [OR], 2.66; 95% confidence interval [CI], 1.40-5.23; P = 0.004). In univariate analysis, hyponatremia was associated with death (OR 4.06, 95% CI, 1.94-8.51; P < 0.000), but there was no statistical significance in multivariate analysis. <bold>Conclusions:</bold> Hyponatremia is present in a quarter of patients treated for TB and is associated with an unfavorable outcome of TB treatment.