1. What is BUN-to-Creatinine Ratio?

The BUN-to-creatinine ratio is a measurement used to help determine the cause of acute or chronic kidney disease or dehydration. It compares the levels of blood urea nitrogen (BUN) to creatinine in your blood.

2. How Does the Calculator Work?

The calculator uses a simple ratio formula:

Where:

• BUN — Blood urea nitrogen concentration in mg/dL
• Creatinine — Serum creatinine concentration in mg/dL

Explanation: The ratio helps differentiate between pre-renal (before the kidney) and intrinsic renal (within the kidney) causes of kidney dysfunction.

3. Clinical Significance

Normal Range: Typically 10:1 to 20:1 (10-20).
High Ratio (>20:1): May suggest pre-renal causes like dehydration, heart failure, or gastrointestinal bleeding.
Low Ratio (<10:1): May suggest intrinsic kidney disease, liver disease, or malnutrition.

4. Using the Calculator

Tips: Enter BUN and creatinine values in mg/dL. Both values must be greater than zero. The result is unitless (a ratio).

5. Frequently Asked Questions (FAQ)

Q1: Why is the BUN/creatinine ratio important?
A: It helps distinguish between different causes of kidney dysfunction and guides appropriate treatment.

Q2: What can affect the BUN/creatinine ratio?
A: Protein intake, hydration status, liver function, muscle mass, and certain medications can all affect the ratio.

Q3: Is the ratio different for children?
A: Yes, children typically have lower ratios (around 10:1) due to higher metabolic rates and lower muscle mass.

Q4: Can medications affect the ratio?
A: Yes, corticosteroids and tetracyclines can increase BUN, while cimetidine and trimethoprim can increase creatinine.

Q5: When is the ratio not useful?
A: In end-stage renal disease or when both BUN and creatinine are markedly elevated, the ratio may lose diagnostic value.