What is the appropriate dose of Lasix (furosemide) for a patient with heart failure and impaired renal function, specifically with an estimated glomerular filtration rate (eGFR) of 36?

From the Guidelines

For a patient with heart failure and an eGFR of 36 ml/min/1.73m², an appropriate starting dose of Lasix (furosemide) would be 20-40 mg once or twice daily, with careful monitoring and dose adjustments based on response. The reduced kidney function requires caution as furosemide is primarily eliminated by the kidneys. Start at the lower end of the dosing range if the patient is diuretic-naive or has not recently taken loop diuretics.

Key Considerations

• Monitor for clinical response (improvement in symptoms, weight loss, fluid status) and watch for side effects including electrolyte abnormalities (particularly potassium, sodium, and magnesium), worsening kidney function, and dehydration.
• Regular laboratory monitoring of electrolytes and kidney function is essential, initially within 3-7 days of starting therapy or changing doses.
• The dose may need to be increased gradually if the patient shows inadequate response, potentially up to 80-120 mg daily in divided doses for patients with significant fluid overload and diuretic resistance.

Mechanism and Rationale

Furosemide works by inhibiting sodium and chloride reabsorption in the loop of Henle, promoting diuresis to reduce fluid overload in heart failure, but this mechanism becomes less efficient with declining kidney function, often necessitating higher doses in patients with reduced eGFR, as supported by the guidelines from the European Society of Cardiology 1.

Clinical Guidance

It is recommended to regularly monitor symptoms, urine output, renal function, and electrolytes during use of i.v. diuretics, and to give diuretics either as intermittent boluses or a continuous infusion, with the dose and duration adjusted according to the patient's symptoms and clinical status 1.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Edema Therapy should be individualized according to patient response to gain maximal therapeutic response and to determine the minimal dose needed to maintain that response. The usual initial dose of Furosemide tablets is 20 to 80 mg given as a single dose. The dose may be raised by 20 or 40 mg and given not sooner than 6 to 8 hours after the previous dose until the desired diuretic effect has been obtained.

The appropriate dose of Lasix (furosemide) for a patient with heart failure and impaired renal function, specifically with an estimated glomerular filtration rate (eGFR) of 36, is not directly stated in the drug label.

• Key consideration: The dose should be individualized according to patient response.
• Initial dose: The usual initial dose is 20 to 80 mg given as a single dose.
• Dose adjustment: The dose may be raised by 20 or 40 mg and given not sooner than 6 to 8 hours after the previous dose until the desired diuretic effect has been obtained.
• Caution: When doses exceeding 80 mg/day are given for prolonged periods, careful clinical observation and laboratory monitoring are particularly advisable 2.

From the Research

Diuretic Strategies for Heart Failure with Impaired Renal Function

The management of heart failure with reduced ejection fraction (HFrEF) in patients with chronic kidney disease (CKD) requires careful consideration of diuretic therapy. For a patient with an estimated glomerular filtration rate (eGFR) of 36, the following points are relevant:

• High-dose furosemide may be effective in patients with severe chronic congestive heart failure and significantly reduced renal function, with a mean endogenous creatinine clearance of 0.53 mL/s/1.73 m2 (32 mL/min/1.73 m2) 3.
• The use of high-dose loop diuretics may be associated with hypokalemia and hyponatremia, but not with reduced survival after multivariate and propensity adjustment 4.
• Metolazone administration may be helpful in patients taking an elevated loop diuretics dose, with better decongestion and diuretic response observed in patients receiving metolazone compared to those receiving traditional loop diuretic treatment 5.
• The starting dose of mineralocorticoid receptor antagonist therapy should be low (e.g., 6.25-12.5 mg daily or 12.5 mg every other day) and can be uptitrated based on the patient's renal function and serum potassium, with an eGFR ≥ 30 mL/min per 1.73 m2 6.
• Loop diuretics are an essential component of therapy for patients with acute decompensated heart failure, but there are few prospective data to guide their use, with no significant differences in patients' global assessment of symptoms or in the change in renal function when diuretic therapy is administered by bolus as compared with continuous infusion or at a high dose as compared with a low dose 7.

Key Considerations

• The presence of CKD should not preclude the use of a renin-angiotensin system inhibitor, although patients should be monitored frequently for worsening renal function and hyperkalemia 6.
• Sacubitril/valsartan is not recommended in patients with an eGFR < 30 mL/min per 1.73 m2 6.
• The sodium-glucose cotransporter 2 inhibitors are effective at reducing adverse cardiovascular and renal outcomes in patients with HFrEF and CKD (eGFR ≥ 25 mL/min per 1.73 m2 with dapagliflozin or ≥ 20 mL/min per 1.73 m2 with empagliflozin) 6.

Diuretic Dosing

• High-dose furosemide (250 to 4000 mg/d) may be effective in patients with severe chronic congestive heart failure and significantly reduced renal function 3.
• The dose of furosemide should be adjusted based on the patient's renal function and response to therapy, with a low dose (equivalent to the patient's previous oral dose) or a high dose (2.5 times the previous oral dose) used in patients with acute decompensated heart failure 7.