Hyponatremia is an inflammatory marker in children with community-acquired pneumonia

Background:

Hyponatremia (HNa) is the most common electrolyte imbalance in clinical practice. HNa is a common finding in children with community-acquired pneumonia (CAP), usually attributed to the syndrome of inappropriate antidiuretic hormone secretion (SIADH). In children with CAP, HNa has been associated with severity. Cytokines as IL-6 may be involved in the occurrence of HNa. We hypothesized that HNa is associated with inflammation and severity in children with CAP. Our abjective is to analyze the association of HNa with severity, inflammatory makers and bacterial etiology in children with CAP.

Methods:

A cohort of hospitalized children with CAP was analyzed. Children were prospectively recruited in 2 hospitals in Madrid, Spain, from April 2012, to March 2015. Clinical and laboratory markers were recorded, including severity features and inflammatory markers. Also, an extensive microbiological work-up was implemented.

Results:

A total of 151 children were recruited. HNa (serum sodium ≤ 135 mM/L) was present in 60/151 patients (39.7%). Sodium ≤ 130 mM/L was present in 5/151 (3.3%) patients. HNa was associated to leucocyte count > 15000/mm³ [p 0.042, OR 1.4 (CI 95% 1.02-1.96)], neutrophil count > 10000/mm³ [p 0.01, OR 1.5 (1.1-2.1)], C-Reactive Protein (CRP) > 40 mg/L [p<0.001, OR 1.5 (CI 95% 1.2-1.8)] and PCT > 1 ng/mL [p<0.001, OR 3 (CI 95% 1.8-4.7)]. Sodium and CRP had a linear correlation (Pearson p<0.001, R -0.393, Spearman p<0.001, R -0.452). HNa was associated with CAP caused by typical bacteria [p<0.001, OR 4.5 (CI 95% 1.8-10)] and O₂ saturation < 92% [p=0.042, OR 1.3 (CI 95% 1.1-1.4)] at admission. Sodium ≤ 130 mM/L was associated to moderate to severe work of breathing [p=0.05, OR 2.6 (CI 95% 1.2-5.7)]. No association was found regarding clinical signs of dehydration, pediatric intensive care unit admission, complicated CAP, need of high flow oxygen-therapy or WHO stage severity.

Conclusion:

Hyponatremia is a common finding in hospitalized children with CAP. HNa has good correlation with inflammatory biomarkers, with typical bacterial etiology and with some severity clinical parameters at admission (SatO₂ < 92% and work of breathing). HNa can be considered as an inflammatory marker.