From the Guidelines
The use of Lasix (furosemide) is not recommended when serum creatinine is elevated due to a prerenal cause, as it can worsen kidney injury by further decreasing blood volume. Signs of acute kidney injury include decreased urine output (oliguria or anuria), fluid retention leading to edema, and elevated blood levels of creatinine and blood urea nitrogen (BUN) 1. Other signs may include electrolyte imbalances, metabolic acidosis, and in severe cases, confusion or shortness of breath. The diagnosis of acute kidney injury is based on the KDIGO criteria, which include a rise in creatinine of >0.3 mg/dl within 48 hours or a 50-99% increase in creatinine from baseline within 7 days, as well as urine output of <0.5 ml/kg/h for more than 6 hours 1. In prerenal acute kidney injury, the primary issue is reduced blood flow to the kidneys. Therefore, the focus should be on addressing the underlying cause of reduced renal perfusion, such as treating hypovolemia, improving cardiac output, or managing sepsis. The appropriate management typically involves:
- Careful fluid resuscitation to improve renal perfusion
- Monitoring urine output
- Addressing the root cause of the prerenal injury In some cases, this may involve administering intravenous fluids, treating infections if present, or managing heart failure. It's crucial to closely monitor kidney function, electrolyte levels, and fluid balance during treatment. Once renal perfusion is restored and kidney function begins to improve, diuretics like Lasix may be considered if there's volume overload, but this should be done cautiously and under close medical supervision. A study by Cotter et al. found that high-dose nitrate therapy was associated with reduced rates of hospital death, myocardial infarction, and intubation in patients with acute heart failure syndrome, whereas high-dose furosemide was associated with worse outcomes 1. Therefore, caution is warranted when using diuretics in patients with acute kidney injury, and the focus should be on addressing the underlying cause of reduced renal perfusion.
From the FDA Drug Label
As with any effective diuretic, electrolyte depletion may occur during furosemide therapy, especially in patients receiving higher doses and a restricted salt intake Hypokalemia may develop with furosemide, especially with brisk diuresis, inadequate oral electrolyte intake, when cirrhosis is present, or during concomitant use of corticosteroids, ACTH, licorice in large amounts, or prolonged use of laxatives. All patients receiving furosemide therapy should be observed for these signs or symptoms of fluid or electrolyte imbalance (hyponatremia, hypochloremic alkalosis, hypokalemia, hypomagnesemia or hypocalcemia): dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, arrhythmia or gastrointestinal disturbances such as nausea and vomiting. Reversible elevations of BUN may occur and are associated with dehydration, which should be avoided, particularly in patients with renal insufficiency
The signs of acute kidney injury that may be associated with furosemide therapy include:
- Oliguria
- Azotemia
- Reversible elevations of BUN
- Electrolyte imbalance (e.g. hypokalemia, hypomagnesemia, hypocalcemia)
- Dehydration
It is not beneficial to use Lasix (furosemide) when serum creatinine is elevated due to a prerenal cause, as furosemide may worsen dehydration and electrolyte imbalance, particularly in patients with renal insufficiency 2. In fact, the drug label recommends that furosemide be discontinued if increasing azotemia and oliguria occur during treatment of severe progressive renal disease 2.
From the Research
Signs of Acute Kidney Injury
- Increase in serum creatinine level with or without reduced urine output 3, 4
- Abrupt deterioration in kidney function 3
- Decrease in urine output to less than 0.5 mL/kg/hour for 6 hours 4
- Increase in serum creatinine level of 0.3 mg/dL or more within 48 hours, or an increase of 1.5 times or more of the baseline level within 7 days 4
Use of Lasix (Furosemide) in Acute Kidney Injury
- Treatment with fluid resuscitation or diuresis is guided by the volume status 4
- Furosemide may be used to manage fluid overload in patients with acute kidney injury, but its use should be cautious and guided by the patient's volume status and renal function 3, 4
- In patients with prerenal acute kidney injury, the use of furosemide may be beneficial in managing fluid overload, but it is essential to address the underlying cause of the prerenal injury 3, 5
Management of Acute Kidney Injury
- Fluid resuscitation and avoidance of nephrotoxic medications 3
- Correction of electrolyte imbalances and management of underlying cause 3, 4
- Renal replacement therapy (dialysis) may be indicated in severe cases 3, 6
- Early determination of etiology, management, and long-term follow-up of acute kidney injury are essential to improve outcomes 5