What are the symptoms of hypokalemia?

Written by Gan Jun
Endocrinology
Updated on March 07, 2025
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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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How is hypokalemia diagnosed?

Hypokalemia refers to a blood potassium level below 3.5mmol/L. Clinically, it is mainly diagnosed through electrolyte tests and arterial blood gas analysis, which can confirm whether a patient has low potassium. After developing hypokalemia, patients may experience symptoms such as fatigue and limb weakness. At this point, treatment should include the oral administration of sustained-release potassium chloride tablets or intravenous infusion of potassium chloride, as well as advising the patient to consume potassium-rich vegetables and fruits to correct hypokalemia. Prolonged hypokalemia can lead to arrhythmia and even endanger the patient’s life. (Medications should be used under the guidance of a clinical doctor, according to the specific situation.)

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How to treat hypokalemia?

After the occurrence of hypokalemia, there are generally two methods of potassium supplementation clinically. The first is oral potassium supplementation, which is relatively safe, and one can also eat fruits or vegetables rich in potassium. The second method is intravenous potassium supplementation. The first thing to note with intravenous supplementation is the patient's urination status. If the patient’s urination is normal, potassium chloride can be administered intravenously but must be diluted. In clinical practice, the concentration of intravenous potassium chloride generally does not exceed 0.3%, so we must pay attention to the concentration during potassium supplementation.

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Clinical manifestations of hypokalemia

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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Why does hypokalemia cause abnormal acidic urine?

Hypokalemia is characterized by a reduction in the concentration of potassium ions in the extracellular fluid, which causes the transfer of three potassium ions from inside the cells to the outside, while two sodium ions and one hydrogen ion move from the outside to the inside of the cells. Due to the decreased concentration of hydrogen ions in the extracellular fluid, metabolic alkalosis can easily occur. At the same time, due to the reduction of blood potassium, the potassium-sodium exchange in the renal tubules decreases. Renal tubular cells secrete more hydrogen ions to exchange with sodium ions, and the reabsorption of bicarbonate ions increases, raising the pH value. This metabolic alkalosis increases the number of hydrogen ions inside the cells and the kidney's hydrogen secretion, thus making the urine acidic, often referred to as paradoxical aciduria.

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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.