Mild hyperkalemia clinical manifestations

Written by Gan Jun
Endocrinology
Updated on November 01, 2024
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When blood potassium exceeds 5.5 millimoles per liter, it is referred to as hyperkalemia. Clinically, mild manifestations of hyperkalemia commonly involve the cardiovascular system, including bradycardia, audible enlargement of the heart, and weakened heart sounds. The electrocardiogram may show a shortened QT interval and peaked T waves. Symptoms related to the neuromuscular system include numbness in the lips and limbs, muscle soreness, and, in severe cases, paralysis of the respiratory muscles, which can lead to suffocation. All cases of hyperkalemia present various degrees of metabolic acidosis or azotemia, among other symptoms.

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Written by Wei Shi Liang
Intensive Care Unit
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Does hyperkalemia cause a fast or slow heart rate?

Hyperkalemia often causes a slowed heart rate and is associated with various arrhythmias. When serum potassium is between 6.6 to 8.0 mmol/L, tented T-waves may be observed. When serum potassium levels rise rapidly, it can lead to ventricular tachycardia or even ventricular fibrillation. On the other hand, a slow increase in serum potassium can cause conduction blocks, and in severe cases, may lead to cardiac arrest. These are the heart rate changes caused by hyperkalemia, which typically result in a slower heart rate.

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Written by Wei Shi Liang
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The difference between hyperkalemia and hypokalemia.

Hypokalemia refers to a serum potassium concentration lower than 3.5mmol/L, and its clinical manifestations are diverse. The most life-threatening symptoms involve the cardiac conduction system and the neuromuscular system. Mild hypokalemia shows on an electrocardiogram as flattened T waves and the appearance of U waves, while severe hypokalemia can lead to fatal arrhythmias, such as torsades de pointes and ventricular fibrillation. In terms of the neuromuscular system, the most prominent symptom of hypokalemia is the loss of tone in smooth muscles and flaccid paralysis in skeletal muscles, which, when involving respiratory muscles, can lead to respiratory failure. Hyperkalemia, on the other hand, refers to a serum potassium concentration exceeding 5.5mmol/L, mainly presenting clinical symptoms in cardiac and neuromuscular conduction. Severe cases can cause bradycardia, atrioventricular conduction block, and even sinus arrest. Mild hyperkalemia, with levels between 5.5 to 6.0mmol/L, shows on an electrocardiogram as peaked T waves. As hyperkalemia continues to increase, it can lead to lengthening of the PR interval or disappearance of the P wave, QRS widening, and eventually cardiac arrest. Regarding the neuromuscular system, the clinical manifestations of hyperkalemia are very similar to those of hypokalemia, including weakness and paralysis of skeletal and smooth muscles.

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Written by Wei Shi Liang
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The effects of hyperkalemia on the body

Hyperkalemia affects the body mainly in three aspects. Firstly, hyperkalemia impacts muscle tissues, clinically manifesting as symptoms such as muscle tremors. Secondly, the effect of hyperkalemia on the heart primarily manifests as decreased excitability, conductivity, and automaticity of the myocardium. It affects electrocardiograms, characterized by a depressed P wave, widened QS wave, reduced R wave, and elevated T wave. Thirdly, hyperkalemia affects acid-base balance; during hyperkalemia, potassium efflux from cells can lead to metabolic acidosis, resulting in alkaline urine.

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Endocrinology
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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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Causes of hyperkalemia

The causes of hyperkalemia may include: First, excessive intake, such as consuming too much high-potassium food, medications with high potassium content, including some traditional Chinese medicines, potassium penicillin, stored blood, and excessive potassium supplementation. Second, it could be due to decreased potassium excretion by the kidneys. When renal insufficiency, acute or chronic renal failure occurs, it is often accompanied by severe hyperkalemia. Third, there is also decreased potassium secretion by renal tubules. When there is a deficiency of corticosteroids, there can be degenerative, asymptomatic hyperkalemia. Hyperkalemia can also occur when renal tubules are insensitive to aldosterone. Fourth, medications that reduce potassium excretion, such as the use of potassium-sparing diuretics, angiotensin-converting enzyme inhibitors, other nonsteroidal anti-inflammatory drugs, cyclosporine, etc., can also cause hyperkalemia. Fifth, the shift of potassium from inside the cells to the extracellular fluid, which can be caused by tissue damage, hypoxia, or the use of certain medications, leading to hyperkalemia.