Creatinine - plasma or serum

Last updated: Friday, 04, June, 2010

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Item Process
Specimen

5 mL blood in lithium heparin or plain tube.

Method

Spectrophotometry.

Reference Interval

Dependent on age.

Child (<12 years): 0.04-0.08 mmol/L
Adult female: 0.05-0.11 mmol/L
Adult male: 0.06-0.12 mmol/L.

Application

Detection of decreased glomerular filtration.

An approximate assessment of creatinine clearance can be calculated directly from plasma creatinine using a formula (eg, Cockcroft-Gault).
See Creatinine clearance.

Interpretation

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.
See also Table 1.

Reference

Gault MH et al. Nephron 1992; 62: 249-256.

Eknoyan G et al. Am J Kidney Dis 2003; 42(4): 617-622.