Clinical manifestations of hyperkalemia

Written by Wei Shi Liang
Intensive Care Unit
Updated on September 04, 2024
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The clinical manifestations of hyperkalemia mainly affect the cardiovascular system, often presenting with slowed heart rate and various arrhythmias. When the blood potassium level is between 6.6 and 8.0 mmol/L, a tent-shaped T-wave can be observed. Rapid increases in blood potassium can lead to ventricular tachycardia, and even ventricular fibrillation. A gradual increase in blood potassium can cause conduction blocks, and in severe cases, cardiac arrest. Sudden death in severe hyperkalemia is mainly due to ventricular fibrillation and cardiac arrest. The second aspect is symptoms related to the neuromuscular system. As the concentration of potassium ions in the extracellular fluid increases, the resting membrane potential drops, leading to muscle weakness and even paralysis, typically more pronounced in the lower limbs and extending upward along the trunk. In severe cases, some patients may experience difficulty in swallowing and breathing difficulties. Symptoms involving the central nervous system mainly include restlessness, confusion, and fainting.

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Written by Wei Shi Liang
Intensive Care Unit
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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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Written by Chen Li Ping
Endocrinology
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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
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Can hyperkalemia be cured?

The main focus is on the cause of hyperkalemia. If hyperkalemia is due to consuming foods rich in potassium, administration of potassium-containing solutions, transfusion of stored blood, use of potassium-sparing diuretics like spironolactone, or prolonged venipuncture causing severe shaking of the blood sample during transport, addressing these causes can prevent the occurrence of hyperkalemia. If hyperkalemia is caused by certain diseases, such as renal failure or adrenal insufficiency, active treatment of the underlying disease is required. If the renal failure is acute, recovery of kidney function might prevent the recurrence of hyperkalemia. However, if there is chronic renal insufficiency, there tends to be a higher recurrence rate of hyperkalemia. Therefore, whether hyperkalemia can be cured largely depends on identifying the underlying cause.

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Written by Wei Shi Liang
Intensive Care Unit
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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
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Why does hyperkalemia cause acidosis?

The concentration of potassium ions in serum is 3.5 to 5.5 millimoles per liter, and concentrations above 5.5 millimoles per liter are considered hyperkalemia. In the state of hyperkalemia, potassium ions in the extracellular fluid move into the intracellular fluid, while hydrogen ions in the intracellular fluid move to the extracellular fluid. At this time, through a compensatory mechanism, there is an increase in hydrogen ions in the extracellular fluid, significantly higher than normal levels, resulting in acidosis. Therefore, hyperkalemia often accompanies metabolic acidosis, which in turn affects the renal tubular epithelial cells, causing an abnormal alkaline urine. This is the main reason why hyperkalemia leads to acidosis.