Review Question - QID 214182

This patient who presents with nausea, vomiting, and yellow halos in his vision is most likely experiencing digoxin toxicity. Digoxin decreases intracellular potassium and increases intracellular sodium and calcium.

Digoxin is a cardiac glycoside that is used to increase cardiac inotropy and contractility. It functions by acting as a direct inhibitor of the sodium potassium ATPase, which subsequently leads to indirect inhibition of sodium/calcium exchange. Together, these effects will lead to increased intracellular calcium concentration and increased myosin activity. Digoxin is one of the first drugs discovered for the treatment of congestive heart failure; however, its use is limited by significant side effects. Digoxin toxicity includes nausea, vomiting, abdominal pain, and yellow visual halos that can progress to hyperkalemia and arrhythmias.

Incorrect Answers:
Answer 1: Decreased sodium, decreased potassium, and decreased calcium would be seen in patients with decreased whole body osmolality, such as patients with syndrome of inappropriate antidiuretic hormone or severe hypovolemia.

Answer 2: Decreased sodium, increased potassium, and decreased calcium would be seen in patients with increased activity of the sodium potassium ATPase with subsequent exchange of sodium for calcium. Digoxin is an inhibitor rather than a potentiator of this pump.

Answer 4: Increased sodium, decreased potassium, and decreased calcium would be seen in patients with an overactive sodium/calcium exchanger; however, no commonly seen disease has this profile of activity.

Answer 5: Increased sodium, increased potassium, and increased calcium would be seen in patients with dehydration due to free water loss. There is no evidence that this patient is dehydrated.

Bullet Summary:
Digoxin use leads to increased intracellular sodium, decreased intracellular potassium, and increased intracellular calcium.