What are the symptoms of hyperkalemia?

Written by Wei Shi Liang

Intensive Care Unit

Updated on September 23, 2024

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Mild hyperkalemia can affect muscle tissues, causing mild muscle tremors, while severe hyperkalemia may reduce the excitability of neuromuscular functions, leading to weakness and even flaccid paralysis in the limbs. Hyperkalemia can also impact the heart, mainly resulting in decreased myocardial excitability, decreased myocardial conductivity, and decreased myocardial automaticity. The effects on the electrocardiogram (ECG) primarily manifest as low and widened P waves, widened QS complexes, decreased R waves, and elevated T waves. Regarding myocardial contractility, hyperkalemia mainly causes a decrease in contractility and can lead to metabolic acidosis.

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Written by Wei Shi Liang

Intensive Care Unit

59sec

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Common Causes of Hyperkalemia

Hyperkalemia is when the serum potassium concentration exceeds 5.5 millimoles per liter. Common causes include excessive potassium intake and large doses of potassium salts, which can lead to hyperkalemia, as well as the use of stored blood. Another cause is reduced potassium excretion; in patients with renal insufficiency, reduced urine output or anuria leads to decreased renal potassium excretion. If potassium supplementation is inappropriate at this time, or if potassium-sparing diuretics are used, severe hyperkalemia can occur. Another scenario is the leakage of intracellular potassium during respiratory and metabolic acidosis, where sodium ion exchange occurs in cells, hydrogen ions enter the cells, and potassium ions leak out to the extracellular space, which can lead to increased blood potassium. These are the common causes of hyperkalemia.

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Written by Wei Shi Liang

Intensive Care Unit

1min 31sec

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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 Chen Li Ping

Endocrinology

1min 13sec

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The Impact of Hyperkalemia on the Heart

Typically, when serum potassium exceeds 5.5 mmol/L, it is referred to as hyperkalemia. The manifestations of hyperkalemia on the cardiovascular system usually include bradycardia and arrhythmias, but generally do not lead to congestive heart failure. Sometimes, there may be cardiac enlargement and diminished heart sounds, with characteristic changes on an electrocardiogram. Finally, when serum potassium reaches 12 mmol/L, some parts of the myocardium may be excited and recover, while others have not yet depolarized, making it very easy to cause tachycardia, flutter, ventricular fibrillation, and even cardiac arrest, leading to death. Therefore, hyperkalemia is also a major cause of sudden cardiac death. Some patients with hyperkalemia may only exhibit arrhythmias and show no neuromuscular symptoms before death, thus a rapid diagnosis is crucial. The severity of hyperkalemia is generally assessed by both the measured serum potassium concentration and changes in the electrocardiogram.

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Written by Chen Li Ping

Endocrinology

58sec

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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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Written by Wei Shi Liang

Intensive Care Unit

1min

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The impact of hyperkalemia on the heart

The effects of hyperkalemia on the heart mainly manifest in the following ways: First, it affects the excitability of the myocardium, as hyperkalemia can cause reduced or even absent myocardial excitability; second, it impacts myocardial conductivity. In hyperkalemia, due to the reduced resting potential, the amplitude and speed of the action potential's phase zero decrease, leading to slowed excitability spread and reduced conductivity; third, it influences the automaticity of the myocardium. In hyperkalemia, due to slowed automatic depolarization, the automaticity is reduced. Additionally, hyperkalemia produces characteristic changes in the electrocardiogram, such as depression or disappearance of the P wave, prolongation of the PR interval, widening of the S wave, and narrowing and peaking of the T wave, which are the main changes in the electrocardiogram due to hyperkalemia.