Agreement between venous blood gas and serum biochemistry measurements for sodium, potassium, chloride, and glucose in children with acute gastroenteritis: A method-comparison study

Acute gastroenteritis (AGE) is a common cause of pediatric emergency department (ED) visits and is frequently associated with dehydration and metabolic disturbances. Rapid assessment of electrolytes and glucose is essential in clinical management. Although venous blood gas analysis provides faster results, its agreement with standard serum biochemistry in pediatric AGE remains unclear. This retrospective observational study included children aged 1 month to 18 years who presented to the pediatric ED with AGE between January 1, 2024, and December 31, 2025, and underwent paired venous BGA and serum biochemical testing during the same visit. A total of 1853 paired measurements were obtained from 1191 patients, as some children contributed multiple paired measurements during repeated testing. Method comparison was performed according to Clinical and Laboratory Standards Institute (CLSI) EP09-A3 guidelines using intraclass correlation coefficients (ICC), paired comparisons, Pearson correlation, and Bland-Altman analysis. Both analyzers demonstrated acceptable intra-device reliability (ICC > 0.70). However, agreement between venous blood gas and serum biochemistry was poor for sodium, potassium, chloride, and glucose, with all inter-method ICC values below 0.70. Mean values differed significantly between methods for all parameters (P < .01). Bland-Altman analysis demonstrated wide limits of agreement (LOA) between the 2 methods; for example, glucose measurements showed a mean difference of 2.1 mg/dL with LOA ranging from -64.3 to 68.5 mg/dL. Venous blood gas electrolyte and glucose measurements are not interchangeable with serum biochemistry in children with acute gastroenteritis. While blood gas analysis may be useful for rapid screening or trend monitoring in urgent settings, confirmatory serum biochemical testing remains necessary for clinical decision-making in pediatric AGE.