A-362 Hemolysis Detection and Flagging of Potassium Results on GEM Premier 7000 with iQM3

Background Blood gas analyzers that report whole blood potassium (K+) are vulnerable to inaccurate results due to in vitro hemolysis. GEM Premier 7000 with iQM3 (GEM 7000) automatically detects hemolysis (plasma free hemoglobin) and flags impacted K+ results. Here, we report the hemolysis impact on K+ measurements and the flagging approach used in the GEM 7000 system. Methods Hemolysis interference was assessed according to CLSI EP07c at low (3.8 mmol/L) and high (5.3 mmol/L) K+ levels. Ultrasonically-lysed whole blood was used to generate a high test pool (100% = 1000 mg/dL hemoglobin). This was mixed volumetrically with a low pool (0% = native blood) to create additional test pools (25%, 50%, and 75%) and analyzed on three (3) GEM 7000 systems. K+ bias at each test pool was calculated from the low pool to generate hemolysis interferograms. Linear regression was performed to determine the hemolysis level that exceeds the interference limit of 7%. Results Hemolysis exceeding the interference limit was ≥ 116 mg/dL for the low K+ and ≥ 147 mg/dL for the high K+ level. These correspond to an elevation of 0.27 mmol/L and 0.37 mmol/L of K+, respectively. Based on this study, the GEM 7000 triggers a hemolysis flag when the detected hemolysis exceeds 115 mg/dL. By default, GEM 7000 hemolysis flags are categorized into mild (116 -300 mg/dL), moderate (301 - 400 mg/dL), and gross (≥401 mg/dL) hemolysis. Conclusions The magnitude of the observed increase in K+ (0.277 - 0.295 mmol/L for every 100 mg/dL of hemoglobin) on the GEM 7000 due to in vitro hemolysis is consistent with previously published reports in the literature. Automated hemolysis detection and flagging of K+ results in GEM 7000 overcome the limitation of the inability to detect hemolysis in blood gas samples.