Derangements of potassium regulation often lead to neuromuscular, gastrointestinal and cardiac rhythm abnormalities. The deviations to both extremes hypo- and hyperkalemia are related to the risk of cardiac arrhythmias.
Hyperkalemia is most frequently caused by renal failure frequently a trigger is suboptimal drug therapy, e. Hypokalemia usually occurrs as a complication of certain illnesses or medications. Interestingly, it was shown that 'modern' food has significantly decreased potassium content. As a result, the tendency towards mild hypokalemia is rather frequent among healthy subjects.
This can be easily corrected by the change of food habits — i. The possible causes of hypokalemia are listed in Table 1. The clinical manifestations of hypokalemia include gastrointestinal hypomotility or ileus, muscle weakness or cramping. The most dangerous aspect of hypokalemia is the risk of ECG changes QT prolongation, appearance of U waves that may mimic atrial flutter, T-wave flattening, or ST-segment depression resulting in potentially lethal cardiac dysrhythmia. The pro-arrhythmic risk of hypokalemia is significantly increased when hypokalemia occurs simultaneously with other pro-arrhythmic settings Table 2.
The QT interval is shorter. The treatment of hypokalemia depends on its severity and etiology. Unlike hyponatremia, in which the total body sodium deficit can be readily estimated, serum potassium may not accurately reflect total body stores. During diabetic ketoacidosis, serum potassium levels may be initially elevated, even when severe depletion of total body potassium is present. Correction of acidosis in diabetic ketoacidosis may cause a precipitous drop in serum potassium levels. Transient, asymptomatic, or mild hypokalemia may spontaneously resolve or may be treated with enteral potassium supplements.
Larger doses may be needed in severe depletion to replenish potassium body storage. When this cause e. The oral drugs leading to increases of potassium levels are potassium-sparing diuretics spironolactone, amiloride , potassium chloride tablets, and ACE inhibitors.
These drugs must always be used with caution to avoid hyperkalemia, which may be as dangerous as hypokalemia. Hypokalemia is a frequent disorder, especially important in cardiac patients.
As far as hyperkalemia also carries substantial risk, it is of utmost importance for a practicing cardiologist to keep the potassium levels within normal limits in all cardiac patients.
Additionally, he observes, catecholamines are frequently raised in patients with heart disease. In conclusion, the author implies that despite the associated increased risk of fatal cardiac arrhythmia sudden cardiac death , hypokalemia is often ignored in patients with heart disease. He suggests that it may be beneficial for these patients to maintain serum potassium at the high end of the normal range.
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Summarized from Kjeldson K. Hypokalemia and sudden cardiac death. Exp Clin Cardiol ; ee Disclaimer May contain information that is not supported by performance and intended use claims of Radiometer's products.
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