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Hypokalemia
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.
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.
The difference between hyperkalemia and hypokalemia.
Hypokalemia refers to a serum potassium concentration lower than 3.5mmol/L, and its clinical manifestations are diverse. The most life-threatening symptoms involve the cardiac conduction system and the neuromuscular system. Mild hypokalemia shows on an electrocardiogram as flattened T waves and the appearance of U waves, while severe hypokalemia can lead to fatal arrhythmias, such as torsades de pointes and ventricular fibrillation. In terms of the neuromuscular system, the most prominent symptom of hypokalemia is the loss of tone in smooth muscles and flaccid paralysis in skeletal muscles, which, when involving respiratory muscles, can lead to respiratory failure. Hyperkalemia, on the other hand, refers to a serum potassium concentration exceeding 5.5mmol/L, mainly presenting clinical symptoms in cardiac and neuromuscular conduction. Severe cases can cause bradycardia, atrioventricular conduction block, and even sinus arrest. Mild hyperkalemia, with levels between 5.5 to 6.0mmol/L, shows on an electrocardiogram as peaked T waves. As hyperkalemia continues to increase, it can lead to lengthening of the PR interval or disappearance of the P wave, QRS widening, and eventually cardiac arrest. Regarding the neuromuscular system, the clinical manifestations of hyperkalemia are very similar to those of hypokalemia, including weakness and paralysis of skeletal and smooth muscles.
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.
The difference between hyperkalemia and hypokalemia
Potassium ions are one of the essential electrolytes necessary for human life. Their physiological functions include maintaining cell metabolism, regulating osmotic pressure and acid-base balance, and preserving cell emergency functions, among others. The normal concentration of serum potassium is between 3.5 and 5.5 millimoles per liter. If it falls below 3.5 millimoles per liter, it is categorized as hypokalemia. If it exceeds 5.5 millimoles per liter, it is categorized as hyperkalemia. Common causes of hypokalemia include insufficient potassium intake, excessive potassium excretion, and the shifting of potassium from outside to inside the cells. The main causes of hyperkalemia include increased intake or reduced excretion of potassium, as well as substantial movement of potassium from inside the cells to the outside. Whenever hyperkalemia or hypokalemia occurs, it should be actively managed.
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.
How to replenish potassium for hypokalemia
After the occurrence of hypokalemia, we usually adopt oral potassium supplementation or intravenous potassium supplementation. Oral potassium supplementation is the safest method clinically, and patients can also be advised to consume potassium-rich fruits or vegetables, etc. On the other hand, there is intravenous potassium supplementation, which must be decided based on the patient's urine output. Generally, potassium supplementation can be carried out only when the patient's urine output is more than 500 milliliters per day. However, the concentration of potassium must be diluted and not administered undiluted to prevent arrhythmias and so on.