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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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.)

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Is hyperkalemia acidosis?

Hyperkalemia is not acidosis, but during acidosis, the hydrogen ions of the gastric fluid within cells enter the cells, causing the potassium ions inside the cells to move to the extracellular fluid, resulting in hyperkalemia. Clinically, it is commonly seen in organic acidosis, lactic acidosis, diabetic ketoacidosis, and acute renal failure causing acidosis. Once hyperkalemia occurs and is diagnosed, immediate treatment should be administered. First, the primary disease should be treated; next, serum potassium should be reduced. In particularly severe cases, bedside hemofiltration can be administered, and the cardiotoxic effects of hyperkalemia should be mitigated.

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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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Why should calcium be supplemented for hyperkalemia?

When high potassium levels trigger ventricular automaticity, it is recommended to administer calcium to counteract its cardiotoxicity. This is because during hyperkalemia, the excitability of the myocardium significantly increases. Calcium ions do not affect the distribution of potassium inside and outside the cells, but they can stabilize the excitability of the heart. Therefore, even if a patient's blood calcium level is normal, calcium should be injected immediately when there is severe arrhythmia. Calcium ions only temporarily counteract the toxicity of potassium to the heart and do not reduce the concentration of potassium in the blood. Thus, they can only serve as a short-term emergency medication. (Medication should be used under the guidance of a doctor.)

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What are the symptoms of hyperkalemia?

The effects of hyperkalemia on the body mainly include the following aspects: First, the impact on muscle tissue: mild hyperkalemia can cause slight tremors in muscles. If the potassium levels continue to rise, this can lead to decreased neuromuscular excitability, resulting in limbs becoming weak and flaccid, and even leading to delayed paralysis. Second, the impact on the cardiac system: it can cause a decrease in myocardial excitability, conductibility, and automaticity. The electrocardiogram shows a depressed P wave, widened QRS complex, shortened QT interval, and peaked T waves. Third, hyperkalemia affects acid-base balance and can lead to metabolic acidosis during hyperkalemia.