Which is better for treating hypokalemia—oral or IV potassium?
—James Nahlik, MD, St. Louis

Optimal treatment for hypokalemia depends on the severity of the potassium deficit and the underlying etiology. In general, when a patient has mild-to-moderate hypokalemia (serum potassium between 3.0 and 3.5 mEq/L), there are few if any symptoms, and oral potassium replacement is typically the most cost-effective and efficacious option. Even moderate-to-severe hypokalemia can be successfully treated with oral replacement, but this may be progressively limited by the gastric irritation frequently seen with higher doses. In the presence of severe symptoms, profound potassium depletion, ongoing acute potassium loss, or an inability to tolerate oral therapy, IV repletion is warranted. However, rapid IV administration of potassium is potentially dangerous and can result in hyperkalemia and cardiac arrhythmia, particularly when transcellular potassium shifts are prominent. Therefore, careful monitoring is required. Further, potassium solutions with concentrations >60 mEq/L can be painful and may require infusion into a central vein (Arch Intern Med. 1990;150:613-617).
—Daniel G. Tobin, MD (111-16)

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