Comparison of Electrolytes and Hemoglobin Testing Between a Blood Gas Analyzer and Core Lab Analyzers

Blood gas analyzers (BGAs) are critical point-of-care testing tools in emergency departments (EDs), but their agreement with core lab analyzers for electrolytes and hemoglobin (Hb) remains uncertain. This study compared BGA and core lab results to evaluate the interchangeability of Hb/electrolytes and assess BGA turnaround time (TAT) for ED time-sensitive care.

Our retrospective analysis included 139 ED patients. We compared potassium (K⁺), sodium (Na⁺), chloride (Cl^-), Hb, hematocrit (Hct), and TAT between the GEM4000 BGA (Instrumentation Laboratory, USA), XN3000 hematology analyzer (Sysmex, Japan), and TBA-FX8 biochemical analyzer (Canon Medical Systems, Japan). Interchangeability was assessed by a three-step protocol according to Clinical Laboratory Improvement Amendments (CLIA).

Significant discrepancies existed between GEM4000 and the core labs in our institution. Interchangeability stratified by clinical acceptable limits (CAL): Cl^- and K⁺ showed good interchangeability; Hb showed moderate interchangeability; Na⁺ and Hct were poor. GEM4000 outperformed core labs in TAT: median full-cycle TAT (fcTAT) was 14.00 min and intra-laboratory TAT (labTAT) 4.00 min, versus TBA-FX8 (median fcTAT 77.00 min) and XN3000 (median fcTAT 48.00 min).

GEM4000 enhances ED care timeliness but has variable interchangeability with core labs. Caution is needed for Na⁺/Hct interpretation; clinical context (e.g., lipid/protein levels) should guide decision-making when discrepancies occur. For Hb and Hct discrepancies specifically, pre-analytical handling of BGA specimens (e.g., adequate mixing, timely testing within 30 min) should also be reviewed to rule out artifact-related errors.