Radiologic Predictors of Hyponatremia in Children Hospitalized With Community-Acquired Pneumonia Miguel Glatstein, MD,*Þ Roni Rozen, MD,* Dennis Scolnik, MB ChB,þ§ Ayelet Rimon, MD,* Galia Grisaru-Soen, MD,||¶ Stephen Freedman, MD,þL and Shimon Reif, MD¶ 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 in- vestigated whether there is a link between the radiological pattern seen in patients with CAP and the occurrence of HNa, hypothesizing that chil- dren with moderate and severe HNawould have a lobar-segmental pattern on chest radiograph. Methods: The medical files and chest radiographs of 54 children with moderate to severe HNa (sodium G130 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 oc- curred 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. Key Words: pneumonia, hyponatremia, lobar-segmental pneumonia, interstitial pneumonia, syndrome of inappropriate antidiuretic hormone secretion (Pediatr Emer Care 2012;28: 764Y766) H yponatremia (HNa) is commonly seen in pediatric emer- gency departments, and 20% of cases occur in patients with pneumonia. 1 The association between pulmonary disease and the development of HNa is well known, and HNa has been described in patients with lung cancer, 2 pulmonary tuberculosis, 3 pneu- monia, 4 Legionella infection, 5 and chronic obstructive pulmo- nary disease. 6 A recent pediatric study showed that mild HNa is common in children with community-acquired pneumonia (CAP) and that the degree of HNa is associated with severity of CAP, as assessed by fever, need for hospitalization, and non- specific serum inflammatory markers. 7 The association between pneumonia and HNa was first noted by Stormont and Waterhouse 4 in 1962. Since then, case reports and small studies failed to elucidate the pathogenesis of the HNa or to link it to specific etiologic causes of pneu- monia. 8 Hyponatremia associated with pediatric pneumonia is most commonly due to the syndrome of inappropriate anti- diuretic hormone secretion (SIADH). 9 This syndrome is char- acterized by HNa and hypoosmolality and results from the inappropriate and continued secretion and/or action of anti- diuretic hormone despite normal or increased plasma volume. 10 Shingi and Dhawan 8 found that HNa was associated with more severe disease in pediatric pneumonia and hypothesized that SIADH was the likely cause for this finding. In their study, 68% of pediatrics patients of HNa with CAP had laboratory parameters typical of SIADH. 8 Dreyfuss et al 11 found that patients with pneumonia have a significant reduction in their ability to lower their urine osmolality. Furthermore, plasma anti- diuretic hormone levels at corresponding serum sodium levels were significantly increased during episodes of pneumonia, rela- tive to levels after recovery. 12 This has prompted some experts to recommend maintenance fluid rates of 50% in children with pneumonia complicated by HNa. 13 Only 2 studies on the asso- ciation between HNa and pneumonia have been published in re- cent years: an adult study in United States 9 and a pediatric study in Italy, 14 but neither studied radiological parameters associated with HNa. The aim of our study was to determine if there are any radiological parameters associated with the development of HNa in patients with CAP. We hypothesized that children with moderate and severe HNa would have a lobar-segmental pattern of airspace disease on chest radiograph. METHODS A retrospective chart review was performed of patients younger than 16 years with moderate to severe HNa and ra- diologically confirmed CAP admitted to our hospital during the 2 years from January 1, 2009, to December 1, 2010. Chest ra- diographs were classified as showing either lobar-segmental or interstitial pneumonia by a radiologist blinded to labora- tory results. Severity of HNa was defined as mild HNa = serum sodium concentration 131Y135 mmol/L, moderate HNa = 126Y130 mmol/L, and severe HNa = less than 125 mmol/L (the normal values for serum sodium at our institution are 135Y145 mmol/L). Only patients with moderate or severe HNa were included in our study. Patients who had received intravenous fluids before being assessed in the emergency department were excluded, as were those in whom the diagnosis was made only after admission for another diagnosis. Data extracted included demographic information, history of illness, hemodynamic sta- tus, admission laboratory values, and radiological pattern of ORIGINAL ARTICLE 764 www.pec-online.com Pediatric Emergency Care & Volume 28, Number 8, August 2012 From the *Division of Pediatric Emergency Medicine, Department of Pedi- atrics, Dana Children’s Hospital; and †Division of Clinical Pharmacology and Toxicology, Ichilov Hospital, University of Tel Aviv, Tel Aviv, Israel; Divi- sions of ‡Pediatric Emergency Medicine and §Clinical Pharmacology and Toxicology, Department of Pediatrics, The Hospital for Sick Children, Uni- versity of Toronto, Toronto, Ontario, Canada; Divisions of ||Infectious Dis- ease and ¶Pediatric Medicine, Department of Pediatrics, Dana Children’s Hospital, University of Tel Aviv, Israel; and LDivisions of Gastroenterology, Hepatology, and Nutrition, Department of Paediatrics, The Hospital for Sick Children and Child Health Evaluative Sciences, The Hospital for Sick Children Research Institute, Health Policy Management and Evaluation, The University of Toronto, Toronto, Ontario, Canada. Disclosure: The authors declare no conflict of interest. Reprints: Miguel M. Glatstein, MD, Division of Pediatric Emergency Medicine, Dana Children’s Hospital, 6 Weizman St, Tel Aviv 64239, Israel (e-mail: Nopasara73@hotmail.com). Copyright * 2012 by Lippincott Williams & Wilkins ISSN: 0749-5161 Copyright © 2012 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.