Editing Pharmacology – RN Practice Questions (section)

==Question 2==
A client with heart failure takes digoxin 0.25 mg daily and furosemide 40 mg twice daily. The client reports nausea, anorexia, and seeing yellow-green halos around lights. Vital signs show an apical pulse of 52 and regular. Which laboratory value should the nurse review first?
# Serum sodium
# Serum potassium
# Serum albumin
# Serum calcium

'''Answer:''' 2 (B) Serum potassium.

''Rationale:'' The client is describing classic digoxin toxicity. Hypokalemia, a very common effect of loop diuretics such as furosemide, potentiates digoxin binding at the sodium-potassium ATPase pump and precipitates toxicity even when the digoxin level is within the usual reference range of 0.5 to 2.0 ng/mL. Potassium is therefore the highest priority value. Sodium, albumin, and calcium can influence drug handling in general, and severe hypercalcemia can worsen digoxin toxicity, but potassium is the immediate and far more common culprit in this scenario, and it is directly correctable.