An urea N result of 9 mg/dL is obtained by a technologist. What is the urea concentration?

• A. 3.2 mg/dL
• B. 4.2 mg/dL
• C. 18.0 mg/dL
• D. 19.3 mg/dL

Answer: (D)

To convert urea nitrogen to total urea concentration, multiply by about 2.14. This factor comes from their molecular weights (urea has two nitrogens and a molecular weight of ~60, while nitrogen is ~28). So 9 mg/dL of urea nitrogen × 2.14 = 19.26 mg/dL, which rounds to 19.3 mg/dL.