Radiologic predictors of hyponatremia in children hospitalized with community-acquired pneumonia

BACKGROUND: Hyponatremia (HNa) is the most common electrolyte imbalance seen in clinical practice and a common laboratory finding in children with community-acquired pneumonia (CAP). This study investigated whether there is a link between the radiological pattern seen in patients with CAP and the occurrence of HNa, hypothesizing that children with moderate and severe HNa would have a lobar-segmental pattern on chest radiograph. METHODS: The medical files and chest radiographs of 54 children with moderate to severe HNa (sodium <130 mmol/L) admitted with CAP over a 2-year period at our institution were retrospectively studied. Community-acquired pneumonia was defined as either lobar-segmental or interstitial by a radiologist blinded to laboratory results. RESULTS: Hyponatremia was seen more frequently in children with lobar-segmental pneumonia: 40 (74%) compared with 14 (26%) with interstitial pneumonia (P = 0.004). There was no relationship between the pattern of pneumonia seen on chest radiograph and severity of HNa; however, all 6 cases of severe HNa had lobar-segmental CAP, and all patients with complicated CAP were from the lobar-segmental group. CONCLUSIONS: We found an association between lobar-segmental CAP and moderate or severe HNa. In addition, all cases of severe HNa occurred in patients with lobar-segmental CAP. The presence of a lobar-segmental pattern on chest radiography in CAP suggests the need for assessment of electrolyte status even in patients with adequate respiratory status.