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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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 Wei Shi Liang
Intensive Care Unit
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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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Written by Gan Jun
Endocrinology
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Patients with hypokalemia can have what kind of urine?

When patients have hypokalemia, they often exhibit paradoxical aciduria, which is a typical manifestation of hypokalemia. In hyperkalemia, however, there is paradoxical alkaline urine. When serum potassium ions decrease, the renal tubular epithelium reduces its potassium excretion function and instead increases hydrogen excretion, leading to increased reabsorption of sodium and bicarbonate. This results in metabolic alkalosis, causing an increase in plasma bicarbonate, unlike typical alkalosis where alkaline urine is excreted. However, in the case of hypokalemia, acidic urine is excreted, hence it is called paradoxical aciduria.

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Written by Wei Shi Liang
Intensive Care Unit
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Precautions for intravenous potassium supplementation in patients with hypokalemia

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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Written by Wei Shi Liang
Intensive Care Unit
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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.