Creatinine Clearance

CPT Code(s):


Collection Procedure:

Serum gel tubes should be centrifuged within 2 hours of collection.

Specimen Requirements:

Type: Peripheral blood

  • Serum, gel
  • Plasma, gel

Sample Volume: 0.5 mL serum

Stability (collection to time of analysis/testing):

  • Refrigerated: 7 days
  • Frozen: 1 year
Unacceptable Conditions: Moderate and gross hemolysis


Estimation of glomerular filtration rate


This Creatinine procedure is a kinetic modification of the Jaffe procedure, in which creatinine reacts with picric acid at alkaline pH to form a yellow orange complex. However, this reaction is not completely specific for creatinine since other reducing substances such as glucose, pyruvate, ascorbic acid, and acetoacetates will react with picrate to form a similar color. Fabiny and Ertingshausen found that alkaline creatinine picrate reaches maximum color development at a different rate than pseudo-creatinine material. Cook utilized different reaction rates of alkaline picrate positive substances to obtain greater specificity with the Jaffe reaction. The rate of change in absorbance at 520/800nm is proportional to the creatinine concentration in the sample.


Within 24 hours