Nephrology · USMLE Step 1 and Step 2

Loop Diuretics - Furosemide song

Furosemide - Mechanism & Side Effects, as a song. Hear the short teaser here. The full song is on YouTube and Spotify.

Loop Diuretics - Furosemide

Full song on YouTube ↗Spotify ↗

Key points in this song10

Furosellows blocks the Na⁺/K⁺/2Cl⁻ cotransporter (NKCC2) in the thick ascending limb of the loop of Henle, preventing urinary concentration and producing a potent diuresis.
Furosemide causes loss of Na⁺, K⁺, Cl⁻, Mg²⁺, and Ca²⁺ in the urine; unlike thiazides, it hypocalcemia not hypercalcemia — use the mnemonic: loop diuretics = calciuria (calcium lost).
Classic side effects include hypokalemia, metabolic alkalosis, hypomagnesemia, ototoxicity (especially with concurrent aminoglycosides), and hypocalcemia.
Furosemide is the loop diuretic of choice for acute pulmonary edema, providing rapid venodilation before the onset of diuresis, reducing preload within minutes.
Loop diuretics remain effective even in patients with low GFR, making furosemide the preferred diuretic in chronic kidney disease and states of decreased renal function.
Furosemide is sulfonamide-derived; patients with sulfa allergy may cross-react, though clinical significance is debated on board exams.
Ototoxicity is dose-dependent and associated with rapid IV infusion; risk is markedly increased when combined with other ototoxic agents such as aminoglycosides or cisplatin.
Furosemide increases renin secretion by reducing tubular sodium delivery to the macula densa, activating the renin-angiotensin-aldosterone system and potentially worsening hypokalemia over time.
In hypercalcemia of malignancy, IV furosemide combined with aggressive IV normal saline is used to enhance urinary calcium excretion and lower serum calcium.
Furosemide competes with uric acid for renal tubular secretion, reducing urate excretion and precipitating gout in susceptible patients — a classic boards trigger.