What is the major cause of artifactual hyperkalemia in blood samples?

• A. Sample hemolysis
• B. Sample hemolysis, thrombocytosis
• C. Sample hemolysis, excessive fist clenching
• D. Sample hemolysis, thrombocytosis, prolonged tourniquet use or excessive fist clenching

Answer: (D)

The major cause of artifactual hyperkalemia in blood samples is multifactorial, and understanding the mechanisms behind these contributing factors is essential for accurate laboratory results.

Sample hemolysis is a primary concern because when red blood cells rupture, they release potassium into the serum, artificially elevating its concentration. This is particularly problematic when samples are processed incorrectly, such as through rigorous handling or extended storage times at room temperature.

The presence of thrombocytosis can also affect potassium levels. When there is an increased number of platelets in the blood, it can lead to elevated potassium readings due to the release of potassium during the clotting process.

Additionally, prolonged tourniquet use or excessive fist clenching prior to blood collection can cause stasis, leading to hemoconcentration. This concentration effect can further skew potassium measurements, as cellular contents may diffuse into the plasma more effectively under these conditions.

Considering these factors collectively provides a comprehensive understanding of why D is the correct answer. It encompasses all the significant contributors to artifactual hyperkalemia, allowing for a better grasp of laboratory practices and the importance of proper sample handling to avoid misleading results.