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Furosemide chalange test

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furosemide AND challenge

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furosemide stress test challenge acute kidney injury cirrhosis ascites guidelines

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furosemide stress test acute kidney injury

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https://pubmed.ncbi.nlm.nih.gov/31035185/

Furosemide challenge test / Furosemide stress test (FST)

A functional test of renal tubular reserve used in patients with early acute kidney injury (AKI), especially with oliguria and fluid overload. It helps predict whether AKI may progress to severe AKI or require kidney replacement therapy (dialysis). It is not a treatment to reverse AKI.

Before the test

Use only when the patient is:
  • Euvolemic or fluid overloaded
  • Hemodynamically stable, with adequate renal perfusion
  • Not significantly hypotensive or actively volume depleted
Correct hypovolemia first. Do not use it simply to “make urine” in a dehydrated or shock patient.

Protocol

Give a single IV furosemide dose:
Prior loop-diuretic useFurosemide dose
Loop-diuretic naive1 mg/kg IV
Recent/prior loop-diuretic exposure1.5 mg/kg IV
Then measure urine output carefully for 2 hours.

Interpretation

  • Urine output ≥200 mL in 2 hours: diuretic-responsive. Lower short-term likelihood of progression to severe AKI.
  • Urine output <200 mL in 2 hours: poor response. Associated with increased risk of progression to KDIGO/AKIN stage 3 AKI and possible need for dialysis.
Textbook reports cite approximately 87% sensitivity and 84% specificity for the <200 mL/2-hour threshold in suitable patients. Tintinalli's Emergency Medicine, p. 610.
The test is prognostic, so a poor result should prompt closer monitoring, nephrology/ICU involvement as appropriate, review of reversible causes, medication and fluid reassessment, and planning for renal replacement therapy if clinical indications arise. Dialysis should not be initiated from the FST result alone. Comprehensive Clinical Nephrology, p. 984.

Important cautions

Avoid or use specialist supervision in:
  • Hypovolemia, hypotension, or shock
  • Active bleeding or uncontrolled sepsis with unstable perfusion
  • Severe electrolyte deficit, especially hypokalemia
  • Known allergy to furosemide
  • Significant risk of ototoxicity with high-dose IV loop diuretic
Monitor blood pressure, urine output, creatinine, potassium, sodium, magnesium, and volume status.
A recent Cochrane review found that diuretics do not prevent AKI or reliably improve renal recovery, which supports using FST as a risk-stratification test, not as definitive AKI therapy (Cochrane review).
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