BUN Creatinine Ratio Calculator
Calculate BUN/creatinine ratio to assess kidney function and identify prerenal vs intrinsic renal causes
Calculate BUN/Creatinine Ratio
Normal range: 8-20 mg/dL (2.9-7.1 mmol/L)
Normal range: 0.7-1.3 mg/dL (62-115 µmol/L)
BUN/Creatinine Ratio Result
Formula: BUN/Creatinine Ratio = BUN (mg/dL) ÷ Creatinine (mg/dL)
Normal range: 10-20 (prerenal >20, intrinsic renal <10)
Medical Disclaimer
This calculator is for educational purposes only and should not replace professional medical advice. BUN/creatinine ratio interpretation must be considered alongside clinical presentation, medical history, and other laboratory findings. Always consult healthcare professionals for medical decisions.
Example Calculation
Case: Dehydrated Patient
BUN: 26 mg/dL
Serum Creatinine: 0.87 mg/dL
Calculation
BUN/Creatinine Ratio = 26 ÷ 0.87
Ratio = 29.9
Interpretation: High ratio (>20) suggests prerenal cause
Normal Values Reference
BUN (Blood Urea Nitrogen)
Normal: 8-20 mg/dL
Normal: 2.9-7.1 mmol/L
Serum Creatinine
Normal: 0.7-1.3 mg/dL
Normal: 62-115 µmol/L
BUN/Creatinine Ratio
Normal: 10-20
Prerenal: >20
Intrinsic renal: <10
Clinical Significance
Helps differentiate prerenal from intrinsic renal causes of elevated creatinine
Useful in acute kidney injury evaluation
Assists in determining underlying pathophysiology
Guides further diagnostic workup and treatment
Understanding BUN/Creatinine Ratio
What is BUN/Creatinine Ratio?
The BUN/creatinine ratio is a laboratory parameter that compares blood urea nitrogen levels to serum creatinine levels. Both substances are waste products filtered by the kidneys, but they behave differently in various disease states.
Clinical Applications
- •Differentiating prerenal from intrinsic renal causes
- •Evaluating acute kidney injury
- •Assessing hydration status
- •Monitoring kidney function
Interpretation Guidelines
High Ratio (>20)
Suggests prerenal cause - kidney hypoperfusion leading to increased urea reabsorption
Normal Ratio (10-20)
Indicates normal kidney function and balanced protein metabolism
Low Ratio (<10)
Suggests intrinsic renal disease - impaired urea reabsorption capacity