How to use furosemide (loop diuretic) in patients with decreased Glomerular Filtration Rate (GFR) or Impaired Renal Function?

From the Guidelines

Furosemide can be used in patients with decreased GFR or impaired renal function, but dosage adjustments and careful monitoring are necessary. According to the most recent and highest quality study 1, for patients with mild to moderate renal impairment (GFR 30-60 ml/min), start with a standard dose of 20-40 mg orally or intravenously, which can be increased gradually as needed. For severe renal impairment (GFR <30 ml/min), higher doses are typically required, often starting at 40-80 mg and potentially increasing up to 160-200 mg per dose. Some key points to consider when using furosemide in patients with decreased GFR or impaired renal function include:

• The medication may need to be administered more frequently or at higher doses because reduced kidney function impairs drug delivery to its site of action in the loop of Henle.
• Monitor patients closely for signs of excessive diuresis, electrolyte imbalances (particularly potassium, sodium, calcium, and magnesium), dehydration, and further deterioration of renal function.
• Regular assessment of blood pressure, electrolytes, and renal function is essential, with testing frequency based on clinical stability and dose changes.
• Despite impaired kidney function, furosemide remains effective because it works on the tubular lumen side of the nephron, reaching its site of action through active secretion into the proximal tubule rather than through glomerular filtration, as noted in earlier studies 1.
• Additionally, the 2021 KDIGO guideline 1 recommends using loop diuretics as first-line therapy for edema management in patients with nephrotic syndrome, and suggests twice daily dosing of loop diuretics, with the option to switch to a longer-acting loop diuretic if necessary.
• It is also important to restrict dietary sodium intake to less than 2.0 g/d, as recommended in the 2021 KDIGO guideline 1.
• Other diuretics, such as thiazides, may be less effective in patients with reduced kidney function, and their use should be tailored to the individual patient's needs, as suggested in the 2012 ESC guideline 1.

From the FDA Drug Label

In patients with renal insufficiency, reversible elevations of BUN may occur and are associated with dehydration, which should be avoided, particularly in patients with renal insufficiency Furosemide tablets may increase the ototoxic potential of aminoglycoside antibiotics, especially in the presence of impaired renal function Furosemide tablets combined with angiotensin converting enzyme inhibitors or angiotensin II receptor blockers may lead to severe hypotension and deterioration in renal function, including renal failure.

Use of Furosemide in Patients with Decreased GFR:

• Furosemide can be used in patients with decreased Glomerular Filtration Rate (GFR) or impaired renal function, but with caution.
• Patients with renal insufficiency are at risk of reversible elevations of BUN, which are associated with dehydration.
• The combination of furosemide with other medications, such as aminoglycoside antibiotics, angiotensin converting enzyme inhibitors, or angiotensin II receptor blockers, may increase the risk of ototoxicity, hypotension, or deterioration in renal function.
• Key Considerations:
  • Monitor serum electrolytes, particularly potassium, and renal function regularly.
  • Avoid dehydration and correct abnormalities promptly.
  • Use lower doses and adjust according to the patient's response.
  • Avoid concomitant use with certain medications, such as aminoglycoside antibiotics, unless necessary.
  • Monitor for signs of ototoxicity, hypotension, or deterioration in renal function. 2 2 3

From the Research

Furosemide Use in Patients with Decreased GFR

• Furosemide, a loop diuretic, can be effective in patients with decreased Glomerular Filtration Rate (GFR) or impaired renal function, particularly in controlling volume overload 4.
• In patients with chronic kidney disease, loop diuretics like furosemide can be more effective than thiazide diuretics in managing volume overload, but the combination of both can be particularly effective 4.
• The use of small doses of furosemide in chronic kidney disease patients with residual renal function undergoing hemodialysis can increase urinary volume and sodium excretion compared to patients not using this drug 5.

Mechanism of Action and Effects on GFR

• Diuretics, including furosemide, act predominantly on tubular sites and do not increase glomerular filtration rate (GFR) 6.
• Furosemide can induce increases in urinary excretion of sodium, potassium, and other electrolytes, which can be beneficial in patients with impaired renal function 7.
• However, acute administration of furosemide may cause a decline in GFR, particularly in subjects with diastolic dysfunction 8.

Clinical Implications

• The combination of low doses of diuretics acting at different functional sites of electrolyte reabsorption in the nephron can be superior in saluretic potency to increasing the dose of either diuretic alone 7.
• Furosemide can be used in patients with decreased GFR, but careful monitoring of renal function and electrolyte balance is necessary to avoid adverse effects 4, 5.
• The choice of diuretic and dosage should be individualized based on the patient's specific condition and response to treatment 4, 6, 7, 5, 8.