Urea, Serum/Plasma


Urea is a major by-product of protein metabolism; urea is synthesised in the liver from ammonia as a result of deamination of amino acids. The kidneys clear more than 90% of blood urea. Urea is freely filtered by the glomerulus and not secreted by the tubules. However, a large portion (40-70%) is passively reabsorbed from the renal tubules. Urea concentration in the blood can vary with diet, hepatic function and numerous disease states.


Urea is frequently requested along with Creatinine to aid in the differential diagnosis of prerenal (cardiac compensation, water depletion or increased catabolism), renal (acute glomerulonephritis, chronic nephritis, polycystic kidney, nephrosclerosis and tubular necrosis) and postrenal (urinary tract obstruction)

Sample Type, Quantity & Conditions

1 ml Serum 1 ml Li-Heparin or K2-EDTA Plasma Stability: 7 Days at 15-25 °C 7 Days at 2-8 °C 1 Year at (-15)-(-25) °C

Special Precautions

Normal Range

Adults: 13-49 mg/dL Infants (< 1 Year): 9-41 mg/dL Children: 11-39 mg/dL

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