Potassium is the major intracellular cation. The concentration of potassium in the erythrocytes is approximately 23 times the concentration in plasma. For this reason, only unhemolyzed samples must be used. Decreased levels of extracellular potassium are characterized by weakness in the muscles, irritability, paralysis, accelerated heartbeat, and eventually cardiac arrest, and may be caused by a poor intake of potassium in the diet, by a redistribution of extracellular potassium, and by an increased loss of body fluids
rich in potassium. Abnormally elevated levels of extracellular potassium produce mental confusion, general weakness, numbness, flaccid paralysis in the extremities, a slowed heart rate, and eventually collapse of the peripheral vascular system and cardiac arrest. Causes of increased potassium levels may be linked to
inappropriate intravenous therapy, dehydration, shock, diabetic ketoacidosis, and severe burns.