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?

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.

This is because potassium sparing diuretics do not lower potassium levels in the blood, unlike other types of diuretics.Potassium is an essential electrolyte that serves nerve and muscular functions and is regulated by the kidneys.Low potassium levels can cause irregular heartbeats and other problems. Therefore, patients taking potassium sparing diuretics should avoid food sources that are high in potassium, such as bananas, avocados, spinach, and potatoes.

Choice A is wrong because thiazide diuretics, such as hydrochlorothiazide, can cause low potassium levels in the blood.

Patients taking thiazide diuretics may need to take potassium supplements or eat more potassium-rich foods to prevent hypokalemia.

Choice B is wrong because osmotic diuretics, such as mannitol, do not affect potassium levels in the blood.

They work by increasing the amount of water in the urine, but do not alter the electrolyte balance.

Osmotic diuretics are mainly used to treat cerebral edema and glaucoma.

Choice D is wrong because loop diuretics, such as furosemide, can also cause low potassium levels in the blood.

They work by inhibiting the reabsorption of sodium and water in the loop of Henle, a part of the kidney.

Loop diuretics are used to treat edema and heart failure.

Normal ranges for potassium in the blood are 3.5 to 5.0 millimoles per liter (mmol/L).