Search...
⌘K
FEUrea
FEUrea
used to differentiate prerenal from intrinsic acute kidney injury, especially in patients receiving diuretics where FENa is unreliable
FEUrea
FEUrea
used to differentiate prerenal from intrinsic acute kidney injury, especially in patients receiving diuretics where FENa is unreliable
Instructions
To calculate, input urine urea, plasma urea, urine creatinine, and plasma creatinine. This test measures how much filtered urea is excreted in urine compared to creatinine clearance. Ensure that all values are from the same collection time. Interpretation must be paired with clinical assessment for accurate diagnosis.
Overview
When to use
Why use
Evidences
Interpretation
FEUrea (%) | Interpretation |
< 35% | Suggests prerenal azotemia (hypoperfusion, volume depletion) |
35–50% | Indeterminate, requires further evaluation |
> 50% | Suggests intrinsic renal injury (e.g., ATN) |
Fractional excretion of urea estimates the percentage of filtered urea excreted in urine: FEUrea = (Urine urea × Plasma creatinine) / (Plasma urea × Urine creatinine) × 100; a classic cutoff uses FEUrea <35–40% to suggest sodium/urea avidity compatible with “prerenal” physiology, and higher values to suggest intrinsic tubular injury
https://pmc.ncbi.nlm.nih.gov/articles/PMC10371381/
In an unselected multicenter ICU cohort (n=203), FEUrea poorly distinguished transient (hypoperfusion) from persistent AKI (AUC 0.59; sensitivity 63%, specificity 54% at 35% cutoff), reflecting sepsis and mixed pathophysiology
https://pmc.ncbi.nlm.nih.gov/articles/PMC3387621/
Prospective heart failure data show FEUrea is meaningfully altered by loop diuretics: mean FEUrea rose by ~5.6% at peak diuresis, reclassifying 27% of patients across the 35% threshold; thus, FEUrea is not immune to diuretic effects and timing matters
https://pmc.ncbi.nlm.nih.gov/articles/PMC7798124/
Narrative updates suggest FEUrea may outperform FENa in diuretic-treated AKI and remain a useful adjunct, but both indices have limited reliability in sepsis and critical illness with complex physiology
Overview
When to use
Why use
Evidences
The Fractional Excretion of Urea (FEUrea) is a clinical tool used in nephrology to assess the etiology of acute kidney injury (AKI). Unlike sodium, whose excretion is affected by diuretics, urea handling by the kidney is relatively preserved, making FEUrea particularly valuable in patients receiving loop or thiazide diuretics.
FEUrea is widely used when evaluating AKI in patients on diuretics, where FENa may be falsely elevated. It is a rapid, inexpensive, and non-invasive calculation requiring only standard laboratory tests. However, its limitations include reduced accuracy in patients with advanced chronic kidney disease, protein-energy malnutrition, or sepsis, where urea handling may be altered.
Clinically, FEUrea provides important insights into the underlying mechanism of AKI and helps guide management, particularly in determining whether aggressive fluid resuscitation is appropriate or whether intrinsic renal damage is more likely.
Overview
When to use
Why use
Evidences
Interpretation
FEUrea (%) | Interpretation |
< 35% | Suggests prerenal azotemia (hypoperfusion, volume depletion) |
35–50% | Indeterminate, requires further evaluation |
> 50% | Suggests intrinsic renal injury (e.g., ATN) |
Fractional excretion of urea estimates the percentage of filtered urea excreted in urine: FEUrea = (Urine urea × Plasma creatinine) / (Plasma urea × Urine creatinine) × 100; a classic cutoff uses FEUrea <35–40% to suggest sodium/urea avidity compatible with “prerenal” physiology, and higher values to suggest intrinsic tubular injury
https://pmc.ncbi.nlm.nih.gov/articles/PMC10371381/
In an unselected multicenter ICU cohort (n=203), FEUrea poorly distinguished transient (hypoperfusion) from persistent AKI (AUC 0.59; sensitivity 63%, specificity 54% at 35% cutoff), reflecting sepsis and mixed pathophysiology
https://pmc.ncbi.nlm.nih.gov/articles/PMC3387621/
Prospective heart failure data show FEUrea is meaningfully altered by loop diuretics: mean FEUrea rose by ~5.6% at peak diuresis, reclassifying 27% of patients across the 35% threshold; thus, FEUrea is not immune to diuretic effects and timing matters
https://pmc.ncbi.nlm.nih.gov/articles/PMC7798124/
Narrative updates suggest FEUrea may outperform FENa in diuretic-treated AKI and remain a useful adjunct, but both indices have limited reliability in sepsis and critical illness with complex physiology
Frequently Asked Questions
Features and Services FAQs
Discover the full range of features and services we offer and how to use them.
Ready to Transform Your Practice?
Join thousands of clinicians saving hours daily with AI-powered documentation.
14-day free trial • No setup fees
Ready to Transform Your Practice?
Join thousands of clinicians saving hours daily with AI-powered documentation.
14-day free trial • No setup fees
Ready to Transform Your Practice?
Join thousands of clinicians saving hours daily with AI-powered documentation.
14-day free trial • No setup fees
DocScrib
AI-powered medical documentation platform revolutionizing clinical workflows through intelligent patient management and secure documentation.
DocScrib
AI-powered medical documentation platform revolutionizing clinical workflows through intelligent patient management and secure documentation.
DocScrib
AI-powered medical documentation platform revolutionizing clinical workflows through intelligent patient management and secure documentation.