Loop diuretics on the NCLEX
Furosemide and the loop class: K+ loss, ototoxicity, dehydration, what to monitor.
Loop diuretics block Na/K/2Cl cotransport in the loop of Henle. Powerful and fast. The NCLEX tests potassium loss, dehydration, and ototoxicity.
Common drugs
Furosemide (Lasix), bumetanide, torsemide, ethacrynic acid (rare, for sulfa allergy).
Action and use
Massive diuresis. Used for HF (fluid overload), pulmonary edema, HTN (less common), hypercalcemia.
Side effects
Hypokalemia (replace or pair with K-sparing). Hyponatremia, hypocalcemia, hypomagnesemia. Ototoxicity with rapid IV push or with aminoglycosides. Dehydration. Sulfa cross-reactivity (use ethacrynic acid if sulfa allergic).
Push slow
IV furosemide push at 20 mg/min max. Faster = ototoxicity risk.
Monitor
K+, Mg+, BUN/creatinine, daily weights, I&O, orthostatic BP.
Frequently asked
Best time to give furosemide?
Morning, to avoid nocturia. Last dose by mid-afternoon for ambulatory patients.
K+ supplements with furosemide?
Often yes. Or pair with spironolactone. Don't combine with ACE/ARB without monitoring.
Quick check
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