Creatinine - plasma or serum
Last updated: Friday, 04, June, 2010
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5 mL blood in lithium heparin or plain tube.
| Reference Interval|
Dependent on age.
Child (<12 years): 0.04-0.08 mmol/L
Detection of decreased glomerular filtration.
An approximate assessment of creatinine clearance can be calculated directly from plasma creatinine using a formula (eg, Cockcroft-Gault).
Increased creatinine levels occur in conditions which decrease the glomerular filtration rate. These may be pre-renal (eg, hypovolaemia, hypotension), renal or post-renal (eg, obstruction).
An artefactual increase in creatinine is seen with some methods in the presence of ketones and some cephalosporins - consult pathologist.
Levels are lower in patients with a reduced muscle mass (eg, the elderly) and this may conceal impairment of renal function.
Gault MH et al. Nephron 1992; 62: 249-256.
Eknoyan G et al. Am J Kidney Dis 2003; 42(4): 617-622.