Urea – Creatinine Ratio

Source:http://lifeinthefastlane.com/education/investigations-tests/urea-creatinine-ratio/

The relationship of urea and creatine is dependent on serum laboratory units used to determine the cause of acute kidney injury.

• In the US the urea is expressed as BUN (Blood Urea Nitrogen) in mg/dL. Elsewhere Urea (U) is expressed as mmol/L
• Similarly Creatinine (Cr) is expressed as mg/dL in the US and µmol/L elsewhere

Therefore two ratio’s exist to compare serum Urea and Creatinine levels

• BUN : Cr ratio with US units of mg/dL : mg/dL
• Urea: Cr ratio ith SI Units of mmol/L: µmol/L (providing Urea is >10mmol/L)
• Cr: Urea ratio with SI Units of µmol/L: mmol/L (providing Urea is >10mmol/L)