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Renal Function

Urea:Creatinine Ratio



  • In the presence of raised creatinine, urea disproportionately higher than creatinine suggests a prerenal cause such as hypovolaemia, heart failure or shock.
    • Interpretation

    • Elevated ratio: >100:1
    • Reduced ratio: <40:1

Elevated Urea:Creatinine Ratio

  • A urea:creatinine ratio >100:1 is commonly used as a marker of prerenal renal failure. Any cause of isolated urea elevation may also elevate the ratio.
    • Causes of Elevated Urea:Creatinine Ratio

    • Prerenal renal failure - hypovolaemia, sepsis, renal venoconstriction
    • Dehydration
    • Protein load - GI bleed (especially upper GI), high protein diet
    • Catabolic state - trauma, sepsis, starvation, corticosteroids

Reduced Urea:Creatinine Ratio

    • Causes of Reduced Urea:Creatinine Ratio

    • Severe liver failure
    • Low protein intake - low protein diet, malnutrition, malabsorption, alcoholism
    • Muscle breakdown - body building, rhabdomyolysis
    • Pregnancy
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