Which factor in blood sample handling can cause artifactual hyperkalemia?

• A. Prolonged tourniquet application or excessive fist clenching
• B. Sample hemolysis
• C. Thrombocytosis
• D. All of these

Answer: (D)

Artifactual hyperkalemia happens when potassium is released during the handling of the blood sample rather than from the patient’s actual blood potassium level. Potassium is mostly inside cells, so anything that damages cells or triggers their leakage can falsely raise the measured value. Prolonged tourniquet time or vigorous fist clenching cause local muscle ischemia and contraction, pushing potassium from muscle cells into the sample. Hemolyzed samples let potassium spill out from red blood cells, directly elevating the reading. Thrombocytosis adds more platelets that release potassium during clotting, so serum potassium can be higher when there are many platelets. Because all these factors can elevate potassium in vitro, they can all contribute to artifactual hyperkalemia.