Measurement of Whole-Blood Potassium—Is It Clinically Safe?

Potassium measurement in whole-blood specimens is fast and convenient and is increasingly offered as an adjunct to blood gas analysis. However, the presence of hemolysis in whole-blood samples cannot be determined by such analytical systems at present. There thus is a risk of reporting misleadingly increased whole-blood potassium for unrecognized hemolyzed samples, with potential for subsequent patient misdiagnosis and mistreatment. The real importance of this theoretical concern is unclear. This study describes the prevalence of hemolysis in blood-gas specimens and assesses the subsequent misreporting of whole-blood potassium as a result of hemolysis. It also assesses the importance of low sample volume, age, and gender as risk factors for sample hemolysis.For 10 days, whole-blood potassium was measured with an AVL Omni 6 blood gas analyzer (Roche Diagnostics) in all arterial blood-gas specimens received by the laboratory. The manufacturer’s suggested reference interval for whole-blood potassium is 3.5–4.5 mmol/L. All blood-gas specimens are collected with BD Preset 3-mL …