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Renal

Fractional Excretion of Urea (FEUrea)

Fraction of filtered urea excreted in urine — distinguishes prerenal from intrinsic AKI and stays valid in patients on diuretics.

Scope: Cutoffs derived largely from adult data; interpret pediatric values alongside the clinical picture.

Inputs

FieldUnitNotes
Urine urea nitrogen mg/dL 1–5000
Blood urea nitrogen (BUN) mg/dL 1–300
Urine creatinine mg/dL 1–1000
Plasma creatinine mg/dL 0.1–30

FAQ

What is the Fractional Excretion of Urea (FEUrea)?

Fraction of filtered urea excreted in urine — distinguishes prerenal from intrinsic AKI and stays valid in patients on diuretics.

What inputs does the Fractional Excretion of Urea (FEUrea) need?

Urine urea nitrogen (mg/dL), Blood urea nitrogen (BUN) (mg/dL), Urine creatinine (mg/dL), Plasma creatinine (mg/dL).

Are there any limitations?

Cutoffs derived largely from adult data; interpret pediatric values alongside the clinical picture.

Related Renal calculators

Estimated GFR (Bedside Schwartz)

Paediatric estimated GFR using the bedside Schwartz (2009) equation.

Urine Anion Gap

Urine anion gap to assess renal NH4+ excretion in normal-anion-gap metabolic acidosis.

Fractional Excretion of Sodium (FENa)

Fraction of filtered sodium excreted in urine — helps distinguish prerenal from intrinsic (ATN) acute kidney injury.

Transtubular Potassium Gradient (TTKG)

Estimates the driving force for potassium secretion in the cortical collecting duct — used to work up hyper- and hypokalaemia.

Calculated Serum Osmolality

Estimates serum osmolality from sodium, glucose and urea — compare with a measured value to derive the osmolar gap.

Fractional Excretion of Magnesium (FEMg)

Fraction of filtered magnesium excreted in urine — distinguishes renal magnesium wasting from extrarenal loss in hypomagnesaemia.

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