The Incidence and Risk Factors of Hyponatremia in Pulmonary Tuberculosis

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.

This study aimed to investigate the frequency and risk factors of hyponatremia in PTB patients.

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.

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.

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.