For artifactual or pseudohyperkalemia, which factor is a common laboratory cause?

• A. Sample Hemolysis
• B. Prolonged tourniquet and clenching leading to hemoconcentration
• C. Thrombocytosis (use plasma)
• D. Blood transfusion (storage lesion)

Answer: (A)

Pseudohyperkalemia happens when potassium is released into the sample after the blood has been drawn, so the measured level looks higher than the patient’s true blood potassium. The most common laboratory cause is hemolysis of the blood sample. When red blood cells rupture, their large store of intracellular potassium spills into the serum or plasma, pushing the measured value up even though the patient’s actual potassium isn’t elevated. This is why samples that are damaged during collection or handling—visibly hemolyzed ones or those processed slowly—often show spuriously high potassium.

Other factors can contribute in specific situations but are less universal. Prolonged tourniquet time or clenched fists can cause changes from hemoconcentration, but they’re not the typical cause of pseudohyperkalemia. Thrombocytosis can lead to higher potassium in serum because platelets release potassium during clotting, so using plasma instead of serum helps prevent that artifact. Stored blood in transfusions can leak potassium from aging red cells, but that’s a transfusion-related storage lesion rather than a routine lab artifact in a single sampled patient. The key idea is that in vitro cell rupture releases potassium, giving a falsely high result.