Urea - plasma or serum

Last updated: Wednesday, 31, March, 2004

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Item Process

5 mL blood in lithium heparin or plain tube.

Reference Interval

Neonate: 1.0-4.0 mmol/L
Adult: 3.0-8.0 mmol/L


Investigation of renal function.


Increased levels are seen with reduced glomerular filtration due to renal or pre-renal disease; bleeding into the gastrointestinal tract; hypercatabolic states.

Reduced values are seen in pregnancy; with water retention; with reduced synthesis as a result of decreased protein intake, severe liver disease, or urea-cycle defects.


Dossetor JB. Ann Int Med 1966; 65: 1287-1299.