Measure the urea concentration in blood serum or plasma
Convert urea to blood urea nitrogen using the formula:
BUN = Urea concentration × 0.467
If urea is reported in mg/dL, multiply by 0.467 to get BUN in mg/dL
If urea is reported in mmol/L, multiply by 2.8 to get BUN in mg/dL
To convert BUN back to urea, use:
Urea = BUN × 2.14
Ensure the same units are used consistently in the calculation
Use the laboratory’s reported reference method or conversion factor if provided