Which sample-related issue can cause a falsely elevated potassium measurement?

Which sample-related issue can cause a falsely elevated potassium measurement?

• A. Lipemia
• B. Hemolysis
• C. Lipid interference
• D. Clotting

Answer: (B)

Potassium is mostly inside cells, especially red blood cells. When a sample is hemolyzed, red cells rupture and release their potassium into the plasma or serum, raising the measured potassium level above the true circulating value. This is the classic reason for a falsely elevated potassium result, and it signals the importance of checking the sample for hemolysis before trusting the result. Lipemic samples mainly interfere with tests that rely on optical measurements, and potassium is measured with an ion-selective electrode, so lipemia typically doesn’t cause a false high. Clotting can cause some potassium release from platelets in serum, but the most consistent and common cause of an artifactual elevation is hemolysis.

Potassium is mostly inside cells, especially red blood cells. When a sample is hemolyzed, red cells rupture and release their potassium into the plasma or serum, raising the measured potassium level above the true circulating value. This is the classic reason for a falsely elevated potassium result, and it signals the importance of checking the sample for hemolysis before trusting the result. Lipemic samples mainly interfere with tests that rely on optical measurements, and potassium is measured with an ion-selective electrode, so lipemia typically doesn’t cause a false high. Clotting can cause some potassium release from platelets in serum, but the most consistent and common cause of an artifactual elevation is hemolysis.