Which electrolyte imbalance can increase the risk of digoxin toxicity?

Hypokalemia is the electrolyte imbalance that can significantly increase the risk of digoxin toxicity. Digoxin works by inhibiting the sodium-potassium ATPase pump, which leads to an increase in intracellular calcium levels and subsequently enhances cardiac contractility. However, potassium and digoxin compete for binding sites on this pump; thus, when potassium levels are low, the effects of digoxin can be amplified. This heightened sensitivity results in increased toxicity as the therapeutic margin can be easily crossed, leading to potentially dangerous effects on the heart.

In contrast, other electrolyte imbalances such as hyperkalemia can actually protect against digoxin toxicity by decreasing digoxin's binding affinity, while hyponatremia and hypercalcemia do not have the same direct impact on digoxin pharmacodynamics and toxicity risk in the context of typical clinical scenarios. Understanding these relationships is crucial for effective management of patients receiving digoxin therapy.