What effect does hemolysis have on potassium measurement?

• A. Hemolysis decreases potassium
• B. Hemolysis releases intracellular potassium, falsely elevating measured potassium
• C. Hemolysis has no effect on potassium
• D. Hemolysis lowers potassium falsely

Answer: (B)

Hemolysis causes potassium to rise in the measured sample because red blood cells hold a high intracellular potassium concentration, and when they burst, that potassium spills into the surrounding fluid. Normal extracellular potassium is about 3.5–5.0 mmol/L, while intracellular potassium is roughly 140 mmol/L. When hemolysis occurs, the released potassium makes the result look higher than it truly is, giving a falsely elevated potassium reading. This is why a hemolyzed sample often requires redraw or careful interpretation.

It doesn’t lower potassium, and it does affect the measurement by increasing it, so the other possibilities don’t fit. To prevent this artifact, ensure gentle blood collection, proper needle gauge, minimal fist clenching, prompt handling, and avoid shaking or rough mixing; if hemolysis is evident, redraw the sample.