When serum potassium levels exceed 5.5 millimoles per liter, it is referred to as hyperkalemia. Elevated serum potassium does not reflect an overall increase in body potassium, but due to limitations in testing methods, the clinical diagnosis of hyperkalemia still relies on combining serum potassium levels with electrocardiogram history. The causes of hyperkalemia are complex and commonly include: First, decreased renal potassium excretion, seen in acute kidney failure or insufficiency in adrenal cortical hormone synthesis and secretion, or long-term use of potassium-sparing diuretics; Second, shifts of potassium from inside the cells, often due to hemolysis, tissue damage, large-scale necrosis of tumors and inflammatory cells, shock, burns, excessive muscle contractions, acidosis, or injection of hypertonic saline or mannitol, which causes dehydration inside cells and leads to potassium leakage, resulting in hyperkalemia; Third, excessive intake of potassium-containing medications, such as high doses of potassium penicillin; Fourth, transfusion of stored blood can lead to hyperkalemia; Fifth, digitalis poisoning can cause hyperkalemia.