Which electrolyte abnormality increases digoxin toxicity risk?

Which electrolyte abnormality increases digoxin toxicity risk?

• A. Hyperkalemia
• B. Hypokalemia
• C. Hypernatremia
• D. Hypocalcemia

Answer: (B)

Digoxin inhibits the Na+/K+-ATPase pump, which increases intracellular calcium and strengthens cardiac contraction. The likelihood of digoxin binding to that pump depends on potassium levels. When potassium is low, there is less competition for the binding site, so digoxin binds more readily and inhibits the pump more strongly. This raises the risk of digoxin toxicity, including dangerous arrhythmias. So hypokalemia is the electrolyte abnormality that increases toxicity risk. Hyperkalemia, by contrast, reduces digoxin binding and lowers the risk, while the other listed abnormalities do not mainline-drive digoxin toxicity.

Digoxin inhibits the Na+/K+-ATPase pump, which increases intracellular calcium and strengthens cardiac contraction. The likelihood of digoxin binding to that pump depends on potassium levels. When potassium is low, there is less competition for the binding site, so digoxin binds more readily and inhibits the pump more strongly. This raises the risk of digoxin toxicity, including dangerous arrhythmias. So hypokalemia is the electrolyte abnormality that increases toxicity risk. Hyperkalemia, by contrast, reduces digoxin binding and lowers the risk, while the other listed abnormalities do not mainline-drive digoxin toxicity.