BUN-to-Creatinine Ratio Calculator

How to calculate BUN-to-Creatinine ratio?

Blood Urea Nitrogen (BUN) and Serum Creatinine are two metabolic waste products excreted by the kidneys. BUN reflects urea production from protein breakdown, while Creatinine is produced at a steady rate by muscle metabolism. Analyzing the ratio between these two markers helps healthcare providers identify the source of kidney stress or injury.

Ratio = BUN (mg/dL) / Serum Creatinine (mg/dL)

Using the calculator: an example

A patient presents with a BUN level of 45 mg/dL and a Serum Creatinine level of 1.5 mg/dL.

Step-by-step calculation:

• Divide BUN by Creatinine (45 / 1.5)
• The result is 30:1
• Interpret result as elevated (suggesting dehydration)

Frequently Asked Questions

What is a normal range?
Typically 10:1 to 20:1.

Can diet affect the result?
Yes, very high protein intake can increase BUN levels.

What causes a low ratio?
Acute tubular necrosis, low protein intake, or severe liver disease.