A nurse in a provider's office is monitoring blood electrolytes for four clients who take digoxin.
Which of the following electrolyte values increases a client's risk for digoxin toxicity?

Taking a loop diuretic with supper is not advisable because it can cause nocturia, which is the need to urinate frequently at night. This can disrupt sleep and affect quality of life.Loop diuretics should be taken in the morning or early afternoon to avoid this problem.

Choice A is wrong because weighing oneself each day before breakfast is a good way to monitor fluid balance and detect any signs of fluid retention or dehydration.This can help adjust the dose of the loop diuretic as needed.

Choice B is wrong because contacting the healthcare provider if shortness of breath returns is a sensible precaution and indicates awareness of the symptoms of worsening heart failure.Shortness of breath is caused by fluid accumulation in the lungs, which loop diuretics help to prevent or reduce.

Choice C is wrong because having a banana with breakfast every morning is a good source of potassium, which can help prevent hypokalemia, a common side effect of loop diuretics.Loop diuretics increase the excretion of potassium in the urine, which can lead to low blood levels of potassium and cause muscle weakness, cramps, fatigue, arrhythmias, and increased sensitivity to digoxin.

This is because low potassium levels (hypokalemia) increase the sensitivity of the heart to digoxin and can lead to toxicity even with normal serum digoxin levels. Digoxin inhibits the sodium-potassium pump on the cardiac cells, which causes potassium to accumulate outside the cells.Low potassium levels in the blood create a larger gradient for potassium to move out of the cells, which enhances the effect of digoxin and can cause arrhythmias.

Choice B is wrong because calcium 9.2 mg/dL is within the normal range (8.5 to 10.2 mg/dL) and does not increase the risk of digoxin toxicity.However, high calcium levels (hypercalcemia) can potentiate the effects of digoxin and cause toxicity.

Choice C is wrong because sodium 140 mEq/L is within the normal range (135 to 145 mEq/L) and does not increase the risk of digoxin toxicity.However, high sodium levels (hypernatremia) can reduce the binding of digoxin to the sodium-potassium pump and decrease its efficacy.

Choice D is wrong because magnesium 2.2 mg/dL is within the normal range (1.7 to 2.4 mg/dL) and does not increase the risk of digoxin toxicity.However, low magnesium levels (hypomagnesemia) can increase the sensitivity of the heart to digoxin and cause toxicity.