BUN/Creatinine Ratio Calculator
Calculate the BUN-to-creatinine ratio with SI unit conversion.
Content updated: View sources
Do not divide total urea mmol/L directly by creatinine mg/dL.
BUN/creatinine ratio
—
Converted BUN
—
Converted creatinine
—
Inputs: BUN mg/dL; creatinine mg/dL
About
This calculator normalizes urea or BUN and creatinine to BUN mg/dL and creatinine mg/dL before calculating their ratio. BUN measures only the nitrogen portion of urea, so total urea mmol/L is not numerically interchangeable with BUN mg/dL. The ratio is contextual laboratory information and is not sufficient on its own to identify a cause of kidney dysfunction.
Formula
Interpretation
Interpretation: Hydration and kidney function affect both values. GI bleeding, protein intake, catabolic states or corticosteroids, liver urea production, and muscle mass can alter the ratio independently.
Limitation: A numerical ratio should be reviewed with trends, the individual analytes, clinical context, and the laboratory method rather than treated as a stand-alone classification.
Worked example: BUN 20 mg/dL and creatinine 1.0 mg/dL gives a ratio of 20.
FAQ
Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.