Know Rules of Thumb to Manage Loop Diuretics

Questions still come up about how to optimize loop diuretics (furosemide, etc) for volume overload or edema in heart failure.

First, ensure that patients are on target doses of meds that improve heart failure outcomes. Loop diuretics only treat SYMPTOMS.

And evaluate other possible causes of fluid retention...such as NSAID use, a high-salt diet, or nonadherence.

Then use a stepwise approach to manage loops...but keep in mind, it can be more art than science. Expect doses to fluctuate.

Stick with furosemide. There’s no good evidence other loops are more effective...despite better absorption. Plus furosemide costs pennies/month...versus about $10 for torsemide or $30 for bumetanide.

Start with 20 to 40 mg in the AM...and titrate every couple of days to the lowest dose that achieves fluid balance.

Increase the dose BEFORE adding a second dose...since loops need to reach a “threshold” concentration to cause diuresis. Think of the mantra, “double the dose until the urine flows.”

For example, titrate to 80 mg in the AM. If that’s not enough, add 80 mg in the afternoon. Expect patients with renal impairment need higher doses.

It’s okay to try switching loops if symptoms persist on max daily doses of furosemide...usually 240 mg, or up to 600 mg in kidney disease.

Consider starting an aldosterone antagonist (spironolactone, etc) if patients aren’t already on one...especially for heart failure with REDUCED ejection fraction (HFrEF) if eGFR is above 30 mL/min.

Then add a thiazide if symptoms persist. Any thiazide is okay, but go with metolazone if eGFR is below 30 mL/min.

Dispel the myth of dosing the thiazide 30 min before the loop. There’s no evidence this works better than dosing at the same time.

Keep a close eye on electrolytes and renal function.

Don’t overdo diuresis in heart failure with PRESERVED ejection fraction (HFpEF). This may worsen symptoms by decreasing preload.

Educate patients to check their weight daily...and to report worsening edema or shortness of breath.

Get more practical pearls, such as equivalent loop doses, in our chart, Loop Diuretic Use in Heart Failure.

Key References
  • Eur J Heart Fail 2019;21(2):137-55
  • Circulation 2013;128(16):e240-e327
  • Eur Heart J 2016;37(27):2129-200
  • Am J Cardiol 2020;125(1):92-9
  • Medication pricing by Elsevier, accessed Jan 2020
Prescriber's Letter. February 2020, No. 360201

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