The Incidence and Risk Factors of Hyponatremia in Pulmonary Tuberculosis

CONTEXT: The syndrome of inappropriate antidiuresis (SIAD) with euvolemic hyponatremia may occur in patients with pulmonary tuberculosis (PTB), but little is known about the clinical characteristics of SIAD-associated hyponatremia in PTB patients. OBJECTIVE: This study aimed to investigate the frequency and risk factors of hyponatremia in PTB patients. METHODS: In this retrospective chart review, we examined the incidence and severity of hyponatremia in PTB patients. Multivariate analysis was conducted to identify risk factors for hyponatremia in PTB patients. RESULTS: Of the 161 patients who were screened, after excluding patients with hyperglycemia and renal failure, we enrolled and analyzed data from 113 participants. Hyponatremia occurred in 40.7% patients (<135 mEq/L). Univariate analysis revealed that the presence of hyponatremia was associated with old age, female sex, low body mass index, high glycosylated hemoglobin, C-reactive protein (CRP), and N-terminal pro-brain natriuretic peptide. Multivariable analysis indicated that hyponatremia was strongly associated with old age (odds ratio, 1.06; 95% CI, 1.03-1.09 for every 1-year age increase) and CRP values (odds ratio, 1.15; 95% CI, 1.03-1.30 for every 1-mg/dL increase in CRP). For 86 patients with blood cortisol measurements, the cortisol level was significantly high in the hyponatremia group. CONCLUSIONS: Hyponatremia was less frequently associated with hyperglycemia, heart failure, renal failure, and other diseases that cause euvolemic hyponatremia; thus, PTB patients may have euvolemic hyponatremia due to SIAD. Administration of hypertonic saline or fluid restriction should be considered in PTB patients with hyponatremia.