Clinical manifestations of hypokalemia

Written by Wei Shi Liang
Intensive Care Unit
Updated on September 05, 2024
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The clinical manifestations of hypokalemia are diverse, with the most life-threatening symptoms affecting the cardiac conduction system and the neuromuscular system. Mild hypokalemia on an electrocardiogram presents as flattened T waves and the appearance of U waves, while severe hypokalemia can lead to fatal arrhythmias such as ventricular tachycardia and ventricular fibrillation. In the neuromuscular system, the most prominent symptoms of hypokalemia are skeletal muscle flaccid paralysis and sustained smooth muscle tension, which can involve the respiratory muscles and lead to respiratory failure. Hypokalemia can also cause insulin resistance or hinder insulin release, leading to significant glucose tolerance abnormalities. Reduced potassium excretion decreases the kidney's ability to concentrate urine, resulting in polyuria and urine with low specific gravity.

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Written by Wei Shi Liang
Intensive Care Unit
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What medicine should be taken for hypokalemia?

The treatment of hypokalemia primarily involves addressing the underlying disease. Symptomatic treatment should avoid excessive potassium supplementation, which can lead to hyperkalemia. The principle of potassium supplementation is as follows: for mild hypokalemia, such as in patients showing clinical signs, oral potassium can be administered at 40-80 millimoles per day. For patients with severe hypokalemia, or those whose gastrointestinal tract cannot utilize potassium, with potassium levels less than 2.0 millimoles per liter, intravenous potassium can be provided. An initial supplementation rate of 10-20 millimoles per hour is relatively safe. In cases of severe hypokalemia with life-threatening clinical signs, a rapid increase to 40-80 millimoles can be achieved in a short period, but close monitoring is necessary.

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Written by Wei Shi Liang
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The impact of hypokalemia on skeletal muscle

In clinical practice, hypokalemia can affect the muscular and nervous conduction systems. The most prominent symptoms of hypokalemia in the neuromuscular system are flaccid paralysis of the skeletal muscles, loss of tension in smooth muscles, and rhabdomyolysis. If the respiratory muscles are involved, it can lead to respiratory failure. Hypokalemia can also lead to insulin resistance, resulting in significantly abnormal glucose tolerance. If hypokalemia occurs clinically, it is crucial to actively treat the primary disease, appropriately supplement potassium, monitor during the supplementation process to avoid hyperkalemia, and closely monitor blood potassium levels with regular reviews.

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Written by Wang Li Bing
Intensive Care Medicine Department
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The earliest clinical manifestations of hypokalemia

Hypokalemia is also relatively common in clinical settings. If the blood potassium level falls below 3.5 mmol, it indicates that the patient has hypokalemia. Clinically, this can affect related systems. For instance, patients may experience general weakness, nausea, vomiting, loss of appetite, and even disorientation. If the patient remains hypokalemic for an extended period, it can lead to arrhythmias, such as premature atrial and ventricular contractions. Once hypokalemia occurs, it must be actively managed by correcting the low potassium levels. Clinically, this can be done by administering potassium chloride sustained-release tablets via nasogastric feeding, as well as consuming potassium-rich vegetables and fruits.

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Written by Wei Shi Liang
Intensive Care Unit
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Symptoms of hypokalemia

The clinical manifestations of hypokalemia are diverse, and the most life-threatening involve the cardiac conduction system and neuromuscular system. Mild hypokalemia is characterized on the electrocardiogram by flattened or absent T waves and the appearance of U waves. Severe hypokalemia can lead to fatal arrhythmias, such as ventricular tachycardia, ventricular fibrillation, or sudden death. In the neuromuscular system, the most prominent symptoms of hypokalemia are skeletal muscle relaxation, paralysis, and loss of tone in smooth muscles, leading to rhabdomyolysis. When respiratory muscles are involved, it can lead to respiratory failure. Hypokalemia can also cause insulin resistance or hinder insulin release, leading to significant glucose intolerance. A decrease in potassium excretion results in a reduced ability of the kidneys to concentrate urine, causing polyuria and low specific gravity urine.

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Written by Wei Shi Liang
Intensive Care Unit
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Causes of hypokalemia

Potassium is one of the essential electrolytes necessary for life. Its physiological functions mainly include maintaining cellular metabolism, regulating osmotic pressure and acid-base balance, and preserving cell stress response, etc. Daily potassium intake is about 100 millimoles, with 90% excreted through the kidneys and the remainder through the gastrointestinal tract. Common causes of hypokalemia include reduced intake, such as long-term inability to eat without timely potassium supplementation. Even though potassium intake decreases, the kidneys continue to excrete potassium, leading to potassium loss. The second cause is increased excretion, which includes losses through the gastrointestinal tract and the kidneys, both of which can lead to hypokalemia. The third cause is the movement of potassium from outside to inside the cells, which can occur during metabolic alkalosis or when glucose and insulin are administered, promoting the transfer of potassium ions into the cells, resulting in hypokalemia.