Furosemide Response Index (FRI) Calculator

Furosemide Response Index (FRI): Explanation and Clinical Context The Furosemide Response Index (FRI) is a clinical tool designed to quantify the early response of patients with acute decompensated heart failure (ADHF) to intravenous loop diuretics. It is calculated as the urine output (mL/hour) divided by the administered loop diuretic dose (mg/day). FRI allows clinicians to identify patients with poor diuretic response early, which has been associated with higher risk of congestion, prolonged hospitalization, and adverse outcomes.

Interpretation is generally stratified as poor response (<0.5 mL/hr per mg), moderate response (0.5–1.0 mL/hr per mg), and good response (>1.0 mL/hr per mg). This tool helps guide adjustments in diuretic therapy, consideration of combination diuretic strategies, and informs clinical decision-making in volume management.