Urea reduction ratio

Required inputs

• Pre BUN
• Post BUN

Equation or source

Lowrie EG. NEJM 1990;323:1001.

Provenance and release status

Equation / algorithm

URR = (pre − post) / pre × 100.

Formula version

urr-v1

Tool version

2.4.0

Clinical risk class

C. HIGH-RISK CLINICAL CALCULATOR

Release status

Temporarily unavailable

Source status

Direct primary source identifier not yet resolved

Clinical review status

Clinical verification incomplete; active calculation unavailable

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 is a calculated estimate, not a prescription, treatment order, or diagnosis.
• Local protocols, the full clinical context, and the primary source must be checked before use.