What are the clinical indications for Furosemide (Lasix)?

Clinical Indications for Furosemide (Lasix)

Furosemide is primarily indicated for the treatment of edema associated with congestive heart failure, cirrhosis of the liver, and renal disease, including nephrotic syndrome, as well as for the treatment of hypertension either alone or in combination with other antihypertensive agents. 1

Primary Indications

1. Edema Management

• Heart Failure

  • First-line diuretic therapy for acute heart failure syndromes
  • Initial IV dosing: 20-40 mg in acute heart failure patients 2
  • For patients on chronic oral therapy, IV bolus should be at least equivalent to oral dose 2
  • Oral dosing typically starts at 40 mg daily, can be increased based on response

• Cirrhosis with Ascites

  • Added to aldosterone antagonists when there is inadequate response to aldosterone antagonists alone
  • Starting dose: 40 mg/day, can be increased stepwise to maximum 160 mg/day (in 40 mg steps) 2
  • Particularly indicated when patients develop hyperkalemia on aldosterone antagonists
  • For recurrent ascites, combination therapy with aldosterone antagonist plus furosemide is recommended 2

• Renal Disease

  • Effective for edema in nephrotic syndrome
  • Used in chronic kidney disease with volume overload
  • High doses (up to 720 mg/day orally) may be needed in resistant cases 3

• Congenital Nephrotic Syndrome

  • Starting dose: 0.5-2 mg/kg per dose IV or orally up to six times daily
  • Maximum dose: 10 mg/kg per day
  • Often given in conjunction with albumin infusions 2

2. Hypertension

• Used as monotherapy or in combination with other antihypertensive agents
• Note: Patients not adequately controlled with thiazides will likely not be adequately controlled with furosemide alone 1
• In pediatric patients with hypertension: Initial dose 0.5-2 mg/kg/day, maximum 6 mg/kg/day 2

Special Clinical Scenarios

Acute Heart Failure Management

• IV furosemide (20-40 mg) recommended for all acute heart failure patients 2
• For patients already on chronic oral therapy, IV dose should be at least equivalent to oral dose 2
• May be administered at the end of albumin infusions (0.5-2 mg/kg) in patients with congenital nephrotic syndrome 2

Pediatric Indications

• Edema associated with heart failure, renal disease, or hepatic disease
• Pediatric dosing: 1-2 mg/kg/dose, up to 6 mg/kg/day 2, 4
• In infants with normal renal function, 1 mg/kg IV dose typically provides significant diuresis 4

Dosing Considerations

• Heart Failure: Start with 40 mg oral daily, can be increased based on response
• Cirrhosis: Add 40 mg when aldosterone antagonists are insufficient, increase stepwise to maximum 160 mg/day 2
• Maximum weight loss during therapy:
  • 0.5 kg/day in patients without edema
  • 1 kg/day in patients with edema 2

Contraindications and Cautions

• Discontinue furosemide if:

  • Severe hyponatremia (serum sodium <120 mmol/L)
  • Progressive renal failure
  • Worsening hepatic encephalopathy
  • Incapacitating muscle cramps 2
  • Severe hypokalemia (<3 mmol/L) 2

• Use with caution in:

  • Patients with renal impairment
  • Hyponatremia
  • Electrolyte disturbances
  • Hepatic encephalopathy (generally contraindicated) 2

Monitoring During Therapy

• Frequent clinical and biochemical monitoring, particularly during the first month of treatment 2
• Monitor electrolytes, especially potassium and sodium
• Monitor renal function
• Assess fluid status and weight changes
• High doses of furosemide (>6 mg/kg/day) should not be given for periods longer than 1 week 2

Clinical Pearls

• Loop diuretics work by inhibiting chloride reabsorption at the ascending limb of the loop of Henle
• Response is related to the concentration of the drug in urine rather than in plasma 5
• In cirrhosis, absorption may be delayed ("flip-flop" model), but bioavailability is generally comparable to normal subjects 6
• Torasemide can be considered in patients with weak response to furosemide 2
• For resistant edema, combination with thiazide diuretics may be more effective than increasing furosemide dose alone 2

Remember that while furosemide provides effective symptom relief in heart failure, some studies suggest it may transiently worsen hemodynamics for 1-2 hours after administration, so careful monitoring is essential in acute settings 2.