Urea

Urea is the end product of protein catabolism. Elevated urea blood levels are associated with hyperuremia or azotemia.

Reference Ranges

Adults
Global17 – 43 mg/dL2.8 – 7.2 mmol/L
Women < 50 years15 – 40 mg/dL2.6 – 6.7 mmol/L
Women > 50 years21 – 43 mg/dL3.5 – 7.2 mmol/L
Men < 50 years19 – 44 mg/dL3.2 – 7.3 mmol/L
Men > 50 years18 – 55 mg/dL3.0 – 9.2 mmol/L
Children
1 – 3 years11 – 36 mg/dL1.8 – 6.0 mmol/L
4 – 13 years15 – 36 mg/dL2.5 – 6.0 mmol/L
14 – 19 years18 – 45 mg/dL2.9 – 7.5 mmol/L
BUN in serum/Plasma
Adults
Global7.94– 20.1 mg/dL2.8 – 7.2 mmol/L
Women < 50 years7.01 – 18.7 mg/dL2.6 – 6.7 mmol/L
Women > 50 years9.81 – 20.1 mg/dL3.5 – 7.2 mmol/L
Men < 50 years8.87 – 20.5 mg/dL3.2 – 7.3 mmol/L
Men > 50 years8.41 - 25.7 mg/dL3.0 – 9.2 mmol/L
Children
1 – 3 years5.14 – 16.8 mg/dL1.8 – 6.0 mmol/L
4 – 13 years7.01 – 16.8 mg/dL2.5 – 6.0 mmol/L
14 – 19 years8.41 – 21.0 mg/dL2.9 – 7.5 mmol/L
Urea/Creatinine ratio20 – 35 [(mg/dL)/(mg/dL)]25 – 40 [(mmol/L)/(mmol/L)]
Urea in Urine26 – 43 g/24h0.43 – 0.72 mol/24h
Each laboratory should check if the reference ranges are transferable to its own patient population and determine own reference ranges if necessary. For diagnostic purposes, the results should always be assessed with the patient’s medical history, clinical examinations and other findings.

Increased in

  1. Impaired renal function
  2. Pre-renal azotaemia e.g. congestive heart failure, shock etc.
  3. Post-renal azotaemia
  4. Gastro-intestinal bleeding
  5. High protein diet
  6. Drugs: corticosteroids, tetracyline

Decreased in

  1. Pregnancy (third trimester)
  2. Severe liver insufficiency
  3. Overhydration
  4. Malnutrition especially decreased protein intake
  5. Lipoid nephrosis

Conversion

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mg/dL
mmol/L

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