Ref: Digoxin Toxicity with Normal Digoxin and Serum Potassium Levels: Beware of Magnesium, the Hidden Malefactor. Rao MPR et al. J Emerg Med 2013 May 16 [Epub ahead of print]
"In the discussion of this case, the authors touch on the following important points:
- Enhanced automaticity and impaired conduction are hallmarks of digoxin toxicity.
- Hypokalemia and hypomagesemia sensitize the myocardium to digoxin
- Digoxin toxicity can be precipitated by conditions such as hypokalemia, hypomagnesemia or hypothyroidism, even if the digoxin level is “normal”.
- Administration of magnesium is contraindicated in patients with bradycardia, AV block, or severe renal failure.
The key take-home lessons:
- Do not depend solely on laboratory values to diagnose digoxin toxicity.
- If digoxin toxicity is suspected, check the magnesium level."