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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Hypokalemia is formed in what way?

Hypokalemia refers to a condition where the serum potassium level is below 3.5 millimoles per liter. The primary cause of hypokalemia is the loss of potassium in the body. Hypokalemia can be classified into three types based on its cause: potassium deficiency hypokalemia, redistributive hypokalemia, and dilutional hypokalemia. Potassium deficiency hypokalemia is mainly characterized by insufficient intake or excessive excretion. Insufficient intake is typically seen in patients who are fasting, have selective eating habits, or suffer from anorexia, while excessive excretion is mainly through gastrointestinal or renal loss of potassium. Redistributive hypokalemia usually occurs due to metabolic or respiratory alkalosis, the recovery phase of acidosis, heavy usage of glucose, instances of periodic paralysis, acute emergency situations, and the use of folic acid and vitamin B12 in treating anemia or repeat transfusions of cold stored washed red blood cells. Dilutional hypokalemia, on the other hand, is mainly caused by the retention of extracellular fluid, leading to excessive water or water intoxication-induced hypokalemia.

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What are the symptoms of hypokalemia?

When the body's blood potassium level falls below 3.5 millimoles per liter, it is called hypokalemia. Hypokalemia can cause adverse symptoms in multiple systems of the body, initially causing weakness and fatigue in the limbs, flaccid paralysis, sluggish and absent tendon reflexes, and in severe cases, respiratory difficulty. At the same time, hypokalemia can lead to a series of central nervous system damages, such as apathy, a blank stare, drowsiness, and confusion; it also causes nausea, poor appetite, abdominal distension, and intestinal paralysis among other adverse gastrointestinal phenomena. Additionally, it can lead to palpitations, and rapid atrial or ventricular arrhythmias, among other adverse phenomena. Therefore, it is crucial to provide timely and proper potassium supplementation and correction of blood potassium levels for patients with hypokalemia.

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Causes of Hypokalemia

Common causes of hypokalemia include insufficient intake or prolonged inability to eat without intravenous supplementation. In such cases, while intake of potassium decreases, the kidneys continue to excrete potassium, leading to a loss of potassium in the blood. Additionally, increased excretion can cause hypokalemia, including losses from the gastrointestinal tract such as vomiting, diarrhea, and continuous gastrointestinal decompression, which results in a loss of digestive fluids rich in potassium. Potassium loss through the kidneys from prolonged use of potassium-wasting diuretics or during the polyuric phase of acute renal failure can also lead to hypokalemia. Furthermore, the shift of potassium from outside to inside the cells can cause hypokalemia.

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How to radically cure hypokalemia?

Hypokalemia must be treated with potassium supplementation while simultaneously addressing the primary condition. For mild hypokalemia, oral potassium can be given in doses of 40 to 80 mmol/day. In cases of severe hypokalemia, where blood potassium is less than 2.0 mmol/L or when life-threatening symptoms are present, intravenous potassium should be administered at a rate of 10 to 20 mmol/L per hour. Regular monitoring of blood potassium levels is necessary, especially in cases of renal dysfunction and cellular uptake impairment. For life-threatening severe hypokalemia, potassium can be administered via central venous lines with close monitoring of blood potassium levels, and the infusion rate can reach up to 40 mmol/L, which can effectively cure hypokalemia.

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Hypokalemia can cause

Hypokalemia can manifest as weakness, a bitter taste in the mouth, lack of appetite, irritability, or mood swings. In severe cases, symptoms like nausea, vomiting, drowsiness, reduced orientation ability, and confusion may occur. In terms of muscle and nerve effects, hypokalemia leads to decreased neuromuscular excitability, and when blood potassium levels fall below 2.5mmol/L, clinical symptoms of muscle weakness appear. If blood potassium levels drop below 2.0mmol/L, flaccid paralysis and disappearance or weakening of tendon reflexes may occur. In severe cases, paralysis of the respiratory muscles and even respiratory failure might develop. For the gastrointestinal tract, common symptoms include lack of appetite, nausea, and vomiting, with severe cases leading to intestinal paralysis. Hypokalemia can cause an increase in heart rate and even ventricular fibrillation, which can be fatal. Additionally, it can result in metabolic alkalosis. Hypokalemia can cause metabolic alkalosis, and vice versa, with each condition potentially leading to the other, often coexisting simultaneously.