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Test Code LAB66 Creatinine, Plasma

Performing Laboratory

St. Louis Children's Hospital Laboratory - Chemistry

Specimen Requirements

Note: This test is also available as part of LAB17, Comprehensive Metabolic Panel (CMP); LAB15, Basic Metabolic Panel (BMP); and LAB19, Renal Function Panel. See Common Panel Test Combinations to avoid duplicate requests if needed.

 

Patient Preparation: None

Collection Container/Tube:

Preferred: Mint green-top lithium heparin (MNTGRN LiHep) tube

Acceptable: Green samplette/microtainer, plain red-top tube, Gold SST gel tube, or Lavender-top (EDTA) tube

Submission Container/Tube: If specimen is coming from outside facility and collected in a microtainer, plain red-top tube, or lavender-top (EDTA) tube aliquot processed sample into a plastic vial for transport (labeling with specimen type).

Specimen Collection Volume: 1.0 mL (minimum 0.6 mL)

Special Instructions: None

 

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: 

AGE MALES     FEMALES      
<6 years: 0.1-0.6 mg/dL 0.1-0.6 mg/dL
6-13 years: 0.2-0.8 mg/dL    0.2-0.8 mg/dL
13-19 years: 0.4-1.2 mg/dL 0.4-1.0 mg/dL
>or= 19 years: 0.8-1.3 mg/dL 0.6-1.1 mg/dL

Critical Value: None established

 

Methodology

Enzymatic Colorimetric 

Limitations

  • Drugs: No interference was found at therapeutic concentrations using common drug panels. Exceptions: Rifampicin, Levodopa and Calcium dobesilate (e.g. Dexium) cause artificially low creatinine results. N-ethylglycine at therapeutic concentrations and DL-proline at concentrations 1 mmol/L (115 mg/L) give falsely high results. Dicynone (Etamsylate) at therapeutic concentrations may lead to false-low results.
  • As tested according to CLSI recommendation, Methyldopa causes artificially low creatinine results.
  • Venipuncture immediately after or during the administration of Metamizole may lead to falsely low results. A significant interference may occur at any plasma Metamizole concentration.
  • 2-Phenyl-1,3-indandion (Phenindion) at therapeutic concentrations interferes with the assay.
  • In very rare cases gammopathy, in particular type IgM (Waldenström's macroglobulinemia), may cause unreliable results

 

Additional Information

FOR SLCH CORE LABORATORY USE ONLY

Lab Processing Instructions: Promptly centrifuge to separate. If specimen is collected in microtainer, plain red-top tube, or lavender-top tube aliquot sample into a Roche false-bottom tube for testing (labeling aliquot with specimen type).

Processed Volume: 0.3 mL plasma/serum

Specimen Stability Information

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

Test Classification and CPT Code

82565

LOINC

2160-0

Last Reviewed

06/2025