Sodium and copeptin levels in children with community acquired pneumonia.

Copeptin has been associated with the severity of pneumonia and its complications. This study was designed to assess the usefulness of copeptin measurement in children with community-acquired pneumonia (CAP) and copeptin's relation with disease severity and sodium equilibrium. The study encompassed 311 patients (227 with pneumonia and 84 healthy controls) aged 8 days-18 years. Clinical findings and inflammatory markers were used to predict the disease severity. We found that the level of copeptin was significantly higher in patients with CAP (median 0.88 ng/mL) vs. healthy children (0.33 ng/mL; p < 0.01). ROC analysis showed a high AUC value (0.87) and the cut-off point for plasma copeptin level was 0.44 ng/mL, with a high sensitivity (89 %) and specificity (73 %) in recognizing pneumonia. Patients with higher copeptin concentrations were at higher risk of hyponatremia (OR 2.43). Yet there was only a weak reverse correlation between the sodium and the copeptin concentrations (Spearmann's rank coefficient = -0.19). The levels of copeptin were higher in hyponatremic patients (0.83 ng/mL) vs. normonatremic patients (0.69 ng/mL; p = 0.02). Copeptin elevation did not reflect the CAP severity measured with traditionally used methods. In conclusion, copeptin elevation is a promising marker of pneumonia, but it reflects neither the disease severity nor sodium concentration.