Which factors can contribute to artifactual hyperkalemia in a blood sample?

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

Answer: (D)

Artifactual hyperkalemia happens when the blood sample itself, not the patient’s true physiology, causes the potassium to appear high. Each factor described can release potassium from cells or concentrate it in the collected specimen.

Prolonged tourniquet time or excessive fist clenching forces muscle cells to release potassium and creates local hemoconcentration, both of which raise the measured potassium in the sample.

Hemolysis directly ruptures red blood cells, spilling their intracellular potassium into the serum or plasma, often causing a noticeable rise in measured potassium.

Thrombocytosis raises the amount of potassium released by platelets during clot formation, so serum from patients with very high platelet counts can show an elevated potassium level even if plasma potassium would be normal.

Because these are all preanalytical artifacts, they can all contribute to artifactual hyperkalemia, making “All of these” the best answer. To minimize this, ensure proper phlebotomy technique, avoid prolonged tourniquets and fist clenching, obtain plasma rather than serum when appropriate, and check for hemolysis before interpreting the result.