Correcting Potassium Concentrations Measured in Hemolyzed Serum, Plasma, and Whole Blood Samples

BACKGROUND: Despite clinical laboratories' efforts to instruct proper techniques for sample collection and handling, specimen hemolysis remains a major preanalytical problem, with the highest rates seen from blood of patients drawn from the emergency department and intensive care units. Of all the analytes that are affected by the presence of hemolysis, the interpretation of potassium is the most clinically significant. Equations have been developed to estimate potassium results following measurement of free hemoglobin. CONTENT: We reviewed the need and methodology for correcting serum or plasma concentrations using serum and plasma free hemoglobin levels from published reports. Hemolysis detection is also now available for potassium tests conducted on whole blood samples. SUMMARY: Correcting for hemolysis using equations involving hemoglobin analysis sometimes produces inaccurate results for potassium and may not be appropriate. Qualitative comments such as a sample being "likely" abnormal may be acceptable. Reporting a range of corrected potassium results may also be appropriate.