BUN/Creatinine Ratio Calculation

Blood Urea Nitrogen (BUN) mg/dL mmol/L

BUN concentration in blood

Serum Creatinine mg/dL μmol/L

Creatinine concentration in blood

Patient Age

Gender Select gender Male Female Other

Clinical Context Select context Routine screening Dehydration assessment Kidney disease evaluation Gastrointestinal bleeding Other

Calculate Ratio Reset

About BUN/Creatinine Ratio

The BUN/Creatinine ratio helps distinguish between prerenal, renal, and postrenal causes of kidney dysfunction.

Clinical Interpretation:

• Normal (10-20:1):
• • Normal kidney function
• • Balanced urea/creatinine
• Elevated (>20:1):
• • Prerenal azotemia
• • Dehydration
• • GI bleeding
• • High protein diet
• Low (<10:1):
• • Liver disease
• • Malnutrition
• • Pregnancy

Common Causes of Elevated Ratio:

• • Dehydration
• • Heart failure
• • Gastrointestinal bleeding
• • High protein diet
• • Corticosteroid use
• • Tetracycline antibiotics

Common Causes of Low Ratio:

• • Liver disease
• • Malnutrition
• • Pregnancy
• • Low protein diet
• • Sickle cell disease

Units Conversion:

• • BUN: 1 mg/dL = 0.357 mmol/L
• • Creatinine: 1 mg/dL = 88.4 μmol/L

Professional Resources:

• • Nephrologist
• • Primary care physician
• • Emergency medicine
• • Internal medicine