Potassium is the major intracellular cation. The concentration in erythrocytes is approximately 23 times the concentration in plasma. Decrease of extracellular potassium is characterized by muscle weakness, irritability, and paralysis; fast heart rates and specific conduction effects are apparent on electrocardiographic examination. Plasma potassium levels less than 3.0 mmol/L are associated with marked neuromuscular symptoms and evidence of a critical degree of intracellular depletion. Abnormally high extracellular potassium levels produce symptoms of mental confusion, weakness, numbness, and tingling of the extremities. The symptoms are apparent at potassium levels greater than 7.5 mmol/L; levels greater than 10.0 mmol/L are in most cases fatal.

SST, minimum volume 1 mL.
Do not allow serum/plasma to remain on the cells aftercentrifugation. Potassium from the red cells will diffuse into theserum, giving falsely elevated results. Gross lipemic specimensshould be cleared by ultracentrifugation

Stability
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days