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Test Code LAB6504 Creatinine Clearance Timed, Blood and Urine

Performing Laboratory

St. Louis Children's Hospital Laboratory - Chemistry

Specimen Requirements

BOTH BLOOD AND TIMED URINE COLLECTION ARE REQUIRED FOR TESTING

(NOTE: 24Hr duration is preferred collection duration of urine for testing)

Blood specimen should be obtained midway into the timed period of urine collection. However, morning blood specimens are acceptable for use with 5 hr urine collections. 

Patient Preparation: None

Collection Container/Tube:

Preferred: 

     Urine: Plain, brown-orange 24-hour urine collection container without preservatives    

     Blood: Mint green-top Lithium heparin (MNTGRN LiHep) tube

Acceptable: Blood: Green samplette/microtainer; plain red-top tube or Gold SST gel tube

Specimen Collection Volume: 

          Urine: Entire urine specimen collected over timed period required

          Blood: 2.0 mL (minimum 0.6 mL)                     

Submission Container/Tube: If specimen is coming from outside facility, mix well and measure total volume before making aliquot with a minimum of 1.0 mL of urine into a plastic leak-proof, screw-capped tube for transport labeling with volume and duration times or send entire 24-hr urine jug.

Special Instructions: 

  1. Refrigerate urine specimen during collection
  2. Note collection start and stop dates and times on collection container
  3. Call lab at 314-454-4268 to obtain 24-hour collection jug if needed
  4. Follow instructions on "Urine Collection"

Sample Rejection

Mislabled or unlabeled specimens

Logistics

Test Availability: Monday-Sunday

Cut-off time: None, performed as received

Turnaround Time: Same Day; 2 hours from receipt in performing lab

Reference Values

Reference Interval: 

CREATININE, BLOOD  
<6 years: 0.1-0.6 mg/dL
6-13 years: 0.2-0.8 mg/dL
13-19 years  
     Males: 0.4-1.2 mg/dL
     Females: 0.4-1.0 mg/dL
≥ 19 years  
     Males: 0.8-1.3 mg/dL
     Females: 0.6-1.1 mg/dL

 

CREATININE, URINE: No reference intervals established

CREATININE CLEARANCE: No reference intervals established

Critical Value: None established

 

Methodology

Enzymatic Colorimetric

Limitations

  • NA

Additional Information

FOR SLCH CORE LABORATORY USE ONLY

Lab Processing Instructions: 

    Urine: Mix well and measure total volume collected. Centrifuge an aliquot of the urine to clear any precipitates aliquoting cleared urine into a Roche false-bottom tube for testing.. 

    Blood: Centrifuge to separate. If specimen is collected in a microtainer or plain, red-top tube aliquot specimen into a Roche false-bottom tube for testing.

Processed Volume: minimum 0.3 mL of each urine and plasma/serum

Analyte Stability:

Specimen Type Temperature      Time
urine (without preservative)     Ambient 2 days  
  Refrigerated     3 days   
  Frozen  6 months       

 

Specimen Type Temperature      Time
Whole blood (unprocessed) Ambient 8 hours
Plasma/Serum (processed) Refrigerated (preferred) 1 month
  Ambient 5 days
  Frozen indefinitely

 

NOTE: Total volume of specimen collected and collection duration period is required. Note this information on the aliquot container label and into LIS system

If urine collection duration is between 18 hours and 30 hours, the specimen should be ordered as a 24 Hour collection (24HR Urine, Creat Clear)

Test Classification and CPT Code

82575

LOINC

Creatinine in Urine:   2161-8

Creatinine, plasma:   2160-0

Volume Ur:    19153-6

Duration:       13362-9

Last Reviewed

06/2025