Hypokalemia is a Recognized Side Effect of Furosemide in Congestive Heart Failure
The correct answer is A. Hypokalemia - this is a well-established and common side effect of furosemide therapy in patients with congestive heart failure, occurring in approximately 3.6% of hospitalized patients receiving the medication.
Evidence from Guidelines and Drug Labels
Furosemide causes hypokalemia through increased urinary potassium excretion, particularly with brisk diuresis, inadequate oral electrolyte intake, or when cirrhosis is present. 1 The FDA drug label explicitly warns that hypokalemia may develop with furosemide therapy, especially with higher doses and restricted salt intake, and that digitalis therapy may exaggerate the metabolic effects of hypokalemia, particularly myocardial effects. 1
European Heart Journal guidelines consistently identify hypokalaemia, hypomagnesaemia, and hyponatraemia as major side effects of loop diuretics including furosemide, alongside hyperuricaemia, glucose intolerance, and acid-base disturbances. 2
Clinical Significance and Monitoring
All patients receiving furosemide should be observed for signs of hypokalemia including weakness, lethargy, muscle cramps, muscular fatigue, arrhythmia, or gastrointestinal disturbances. 1 The guidelines recommend checking blood pressure, renal function, and electrolytes 1-2 weeks after each dose increment, at 3 months, and subsequently at 6-month intervals. 2
Serum electrolytes, particularly potassium, should be determined frequently during the first few months of furosemide therapy and periodically thereafter. 1 This is especially critical in patients vomiting profusely or receiving parenteral fluids. 1
Supporting Research Evidence
Large-scale surveillance data confirms hypokalemia as the second most common adverse reaction to furosemide, occurring in 3.6% of 2,367 hospitalized patients receiving the medication (78% of whom had congestive heart failure as the indication). 3 The study found that among furosemide recipients who also received potassium supplements or potassium-sparing diuretics, hypokalemia was less frequent, less severe, and of slower onset. 3
Additional research demonstrates that high-dose furosemide (10 mg/kg/day) causes more severe hypokalemia than lower doses, with one patient in a comparative study sustaining sudden death while experiencing severe hypokalemia. 4
Why the Other Options Are Incorrect
- Bronchospasm (B) is not a recognized side effect of furosemide and is more commonly associated with beta-blockers
- Hypoglycemia (C) is incorrect - furosemide actually causes hyperglycemia, with increases in blood glucose and alterations in glucose tolerance tests documented in the FDA label 1
- Hemolytic anemia (D) is not a characteristic side effect of furosemide, though blood dyscrasias should be monitored as with many medications 1
Management Strategies
Potassium-sparing diuretics should only be used if hypokalaemia persists after initiation of therapy with ACE inhibitors and diuretics, with careful monitoring of serum potassium and creatinine after 5-7 days and titration accordingly. 2 The guidelines recommend starting with 1-week low-dose administration and rechecking every 5-7 days until potassium values are stable. 2
For patients with diuretic-induced hypokalemia despite concomitant ACE inhibitor therapy, adding potassium-sparing diuretics such as spironolactone (25-100 mg daily), amiloride (5-10 mg daily), or triamterene (50-100 mg daily) is more effective than chronic oral potassium supplements. 2, 5