BUN Creatinine Ratio Calculator

Calculate the ratio of blood urea nitrogen (BUN) to serum creatinine to help determine the cause of acute kidney injury.

Enter Values

BUN (mg/dL)

Serum Creatinine (mg/dL)

Enter values above and click Calculate to see your result.

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Ratio = BUN / Serum Creatinine

A high ratio (>20:1) suggests a pre-renal cause, while a lower ratio (<10:1) may suggest intrinsic renal damage.

BUN 40, Creatinine 1.0 -> Ratio 40.

A normal ratio is typically between 10:1 and 20:1.

A high ratio often indicates "pre-renal" causes such as dehydration, congestive heart failure, or gastrointestinal bleeding.

This usually indicates kidney damage (intrinsic renal disease) or an obstruction (post-renal).

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