Summary

Background: Hyponatremia is common among hospitalized children, including those with community acquired pneumonia. The prevalence and severity of hyponatremia were reported to correlate with disease. However, data regarding the association between hyponatremia and causative infectious pathogens are limited and results are inconsistent.

Objectives: To investigate the associations between sodium levels, severity and causative pathogen in children with pneumonia.

Methods: A retrospective study of all children (< 18 years) hospitalized with pneumonia from 1 January 2018 to 31 December 2020. Admission sodium levels were compared to the presumed etiological pathogens, clinical parameters, and inflammatory markers.

Results: Among 751 (52% males) children, 10 (1%) had sodium levels < 130 mEq/L, 187 (25%) had mildly decreased levels 130–134 mEq/L, and the remaining 554 (74%) had normal levels 135–145 mEq/L. Sodium levels < 130 mEq/L were found in 7/236 (3%) of the patients with presumed bacterial pneumonia, in 0/20 of patients with presumed atypical-bacterial, and in only 3/495 (0.6%) of the patients with a presumed viral infection, P < 0.001. Sodium levels < 135 mEq/L conferred an odds ratio of 3.1 (95% confidence interval [95%CI] 2.1–4.3) and levels < 130 mEq/L an odds ratio of 6.8 (95%CI 1.8–33.0) for bacterial infection, P < 0.001 for both. Hyponatremia was also inversely associated with high white blood cell counts, absolute neutrophil cell counts, and C-reactive protein levels.

Conclusions: Hyponatremia was common among children hospitalized with pneumonia and was associated with elevated inflammatory markers and presumed bacterial pneumonia.