Renal failure index (RFI)

Required inputs

• Urine Na mEq/L
• Serum Cr
• Urine Cr

Equation or source

Espinel CH. JAMA 1976;236:579.

Provenance and release status

Equation / algorithm

UNa × PCr / UCr. >1 favors intrinsic AKI.

Formula version

rfi-v1

Tool version

2.4.0

Clinical risk class

B. CLINICAL DECISION-SUPPORT CALCULATOR

Release status

Under clinical review

Source status

Direct primary source identifier not yet resolved

Clinical review status

Under clinical verification

Clinical review date

Clinical review date not yet documented

DOI / PMID / direct guideline identifier not yet documented.

Assumptions

• Entered values and units are accurate and apply to the population described by the cited source.
• The published equation or rule is being used without a patient-specific clinical adjustment.

Important limitations

• The result does not replace clinical assessment or establish a diagnosis.
• Performance outside the source population may differ.