Precautions for intravenous potassium supplementation in patients with hypokalemia

Written by Wei Shi Liang
Intensive Care Unit
Updated on September 02, 2024
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Patients with hypokalemia should closely monitor their blood potassium levels when receiving intravenous potassium supplementation, rechecking potassium levels within 1-4 hours after supplementation. Continuous electrocardiogram monitoring is necessary to closely observe any changes in the electrocardiogram and prevent life-threatening hyperkalemia. In patients with renal impairment, the potassium supplementation should be 50% of that for normal patients, and it is generally considered that the daily potassium supplementation should not exceed 100-200 mmol. For patients with severe hypokalemia, the total daily potassium supplementation can reach 240-400 mmol, but blood potassium levels should be closely monitored to prevent hyperkalemia. Peripheral administration of high-concentration potassium can irritate the vein wall, causing pain and phlebitis. Generally, it is considered that the rate of potassium supplementation through peripheral veins should not exceed 40 mmol/L.

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Why does hypokalemia cause alkalosis?

Hypokalemia can cause metabolic alkalosis because it leads to the intracellular movement of hydrogen ions. In hypokalemia, potassium shifts from the inside to the outside of the cell to compensate for the decreased serum potassium. As an exchange, hydrogen ions from the gastric fluid move into the cells, causing cellular alkalosis and intracellular acidosis. Additionally, due to potassium deficiency in the renal tubular epithelial cells, the potassium-sodium exchange decreases and the sodium-hydrogen exchange increases, leading to enhanced excretion of hydrogen ions and increased reabsorption of bicarbonate ions, resulting in hypokalemia-induced metabolic alkalosis, which needs to be promptly addressed clinically.

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How is hypokalemia tested?

Hypokalemia can be diagnosed by drawing 3-5ml of venous blood for biochemical and electrolyte tests. Patients with hypokalemia may experience weakness or even paralysis, hence it is crucial to actively treat by replenishing potassium. During potassium supplementation, it is also important to clarify the underlying cause of the hypokalemia in order to solve the issue from its root. Otherwise, merely supplementing potassium might result in recurring hypokalemia.

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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.

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Can people with hypokalemia smoke?

Hypokalemia is not directly related to smoking. However, once hypokalemia occurs, there is definitely an underlying disease. In the case that the primary disease is not controlled, it is advisable to avoid smoking. Potassium is an essential electrolyte for life, and its physiological functions mainly include maintaining cellular metabolism, regulating osmotic pressure, acid-base balance, and maintaining cell stress functions. Once hypokalemia occurs, active treatment should be implemented, primarily addressing the primary disease, symptomatic treatment with potassium supplementation, and avoiding the occurrence of hyperkalemia. The principle of potassium supplementation is that for mild hypokalemia without clinical manifestations, oral potassium should be given; in cases of severe hypokalemia, intravenous potassium supplementation should be administered immediately. Intravenous potassium should ideally not use peripheral veins but establish a central vein, and the speed of potassium supplementation and the monitoring of potassium levels should be controlled.

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Clinical symptoms of hypokalemia

Hypokalemia has diverse clinical manifestations. The most life-threatening symptoms involve the cardiac conduction system and the neuromuscular system. In mild hypokalemia, the electrocardiogram (ECG) shows flattened T waves or their disappearance, along with the appearance of U waves. Severe hypokalemia can lead to lethal arrhythmias, such as ventricular tachycardia, ventricular fibrillation, or sudden death. In the neuromuscular system, the most prominent symptoms of hypokalemia are in the skeletal muscle, presenting as sluggish paralysis and loss of tone in the smooth muscle, leading to rhabdomyolysis. If respiratory muscles are affected, it may result in respiratory failure. Hypokalemia can also cause insulin resistance and obstruct insulin release, leading to significant glucose tolerance abnormalities. Decreased potassium excretion reduces the kidney's ability to concentrate urine, resulting in polyuria.