Which electrolyte abnormality increases the risk of digoxin toxicity?

Which electrolyte abnormality increases the risk of digoxin toxicity?

• A. Hyperkalemia
• B. Hypomagnesemia
• C. Hypercalcemia
• D. Hypokalemia

Answer: (B)

Low magnesium increases the risk of digoxin toxicity because magnesium plays a role in how digoxin interacts with the Na+/K+-ATPase pump in heart cells. When magnesium is deficient, digoxin’s inhibitory effect on that pump becomes more pronounced, leading to greater intracellular calcium buildup and a higher likelihood of dangerous cardiac effects such as bradycardia and arrhythmias. Correcting the magnesium deficiency helps reduce this risk and is a key part of treating digoxin toxicity. While other electrolyte disturbances can influence toxicity (for example, very low potassium can also raise risk), the question highlights that low magnesium specifically heightens sensitivity to digoxin.

Low magnesium increases the risk of digoxin toxicity because magnesium plays a role in how digoxin interacts with the Na+/K+-ATPase pump in heart cells. When magnesium is deficient, digoxin’s inhibitory effect on that pump becomes more pronounced, leading to greater intracellular calcium buildup and a higher likelihood of dangerous cardiac effects such as bradycardia and arrhythmias. Correcting the magnesium deficiency helps reduce this risk and is a key part of treating digoxin toxicity. While other electrolyte disturbances can influence toxicity (for example, very low potassium can also raise risk), the question highlights that low magnesium specifically heightens sensitivity to digoxin.