The difference between hyperkalemia and hypokalemia

Written by Wei Shi Liang
Intensive Care Unit
Updated on September 01, 2024
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Potassium ions are one of the essential electrolytes necessary for human life. Their physiological functions include maintaining cell metabolism, regulating osmotic pressure and acid-base balance, and preserving cell emergency functions, among others.

The normal concentration of serum potassium is between 3.5 and 5.5 millimoles per liter. If it falls below 3.5 millimoles per liter, it is categorized as hypokalemia. If it exceeds 5.5 millimoles per liter, it is categorized as hyperkalemia.

Common causes of hypokalemia include insufficient potassium intake, excessive potassium excretion, and the shifting of potassium from outside to inside the cells. The main causes of hyperkalemia include increased intake or reduced excretion of potassium, as well as substantial movement of potassium from inside the cells to the outside. Whenever hyperkalemia or hypokalemia occurs, it should be actively managed.

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Hyperkalemia is seen in which diseases?

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.

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Clinical manifestations of hyperkalemia

The clinical manifestations of hyperkalemia are not specific. Early symptoms often include numbness in the limbs, sensory abnormalities, extreme fatigue, and muscle pain. In severe cases, there can be difficulties in swallowing, speaking, and breathing, paralysis of the limbs, and tendon reflexes may disappear. The central nervous system may show signs of restlessness, fainting, and confusion. Some may experience a slow heart rate, ventricular fibrillation, and in the most severe cases, it can lead to cardiac arrest. Other symptoms may include nausea, vomiting, diarrhea, and other gastrointestinal symptoms.

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Common causes of hyperkalemia

Hyperkalemia is caused by increased intake or decreased excretion, or by the transfer of potassium ions from inside the cells to the outside. Increased intake generally does not cause hyperkalemia in individuals with normal kidney function, unless potassium is supplemented intravenously in excessive amounts or too quickly. Moreover, decreased excretion is a major cause of hyperkalemia, typically seen in renal failure, deficiency of adrenocortical hormones, and primary renal tubular disorders in potassium secretion. Additionally, a large transfer of potassium ions from inside the cells to the outside can occur in conditions such as massive cell breakdown, acidosis, tissue hypoxia, periodic paralysis, and insulin deficiency.

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Causes of Hyperkalemia

Common causes of hyperkalemia in clinical settings include: First, it is related to excessive intake. Generally, a high-potassium diet under normal kidney function does not cause hyperkalemia. It only occurs when there is excessive or rapid intravenous potassium supplementation, or when kidney function is impaired. Second, hyperkalemia caused by reduced excretion. Common reasons include renal failure, lack of adrenocortical hormones, and primary renal tubular potassium secretion disorders, all of which can cause hyperkalemia. Third, a large transfer of potassium ions from inside the cells to the outside can also cause hyperkalemia.

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How is hyperkalemia treated?

For hyperkalemia, commonly used clinical treatments include firstly diuretics, which increase the excretion of potassium, thus increasing its discharge from the body. Additionally, hypertonic glucose with insulin is used intravenously to facilitate the movement of potassium from outside to inside the cells. Sodium bicarbonate can also be used to correct acidosis, which can likewise reduce blood potassium levels. When hyperkalemia causes ventricular arrhythmias, calcium injections should be administered immediately to counteract the cardiac toxicity of high potassium. If these treatments do not result in significant effects and the condition is critical, emergency hemodialysis or peritoneal dialysis can be performed to lower blood potassium levels. (Medication should be administered under the guidance of a doctor.)