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Urea

Blood Urea Nitrogen (BUN) Serum Urea
Serum (SST) mmol/L

About this test

End product of protein catabolism, synthesised in the liver. Filtered and partially reabsorbed by the kidney. Rises with renal impairment and catabolic states.

Reference Ranges

Sex Age Range Notes
All ≥ 18 yrs 2.5 – 7.8 Adult

Clinical Interpretation

Low / Decreased
Low — liver failure, malnutrition, pregnancy (haemodilution).
High / Increased
Elevated — prerenal azotaemia, AKI, CKD, high-protein diet, GI bleeding (upper GI blood raises urea disproportionately), catabolism.

Related Tests

Creatinine
Specimen
Serum (SST)
Reporting Unit
mmol/L
Category
🧪 Clinical Biochemistry

⚠ Clinical Note
Reference ranges are indicative. Always interpret results in the context of the individual patient and local laboratory reference intervals, which may vary.