C-Peptide
Label Mnemonic: CPEP
Epic Lab Code: LAB521
Downtime Form: A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
Chemistry
6240 RCP
356-3527
Specimen(s):
Plasma
Collection Medium:
Plasma Separator Tube 4.5 mL
Alternate Collection Media:
Call laboratory for additional acceptable specimen collection containers.
Minimum:
5 mL whole blood in light green top tube (adults) or TWO Microtainer® devices (pediatric patients).
Testing Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around Time:
1 hour (upon receipt in laboratory)
Reference Range:
1.1-4.4 ng/mL in fasting specimens

Reference interval applies to fasting specimens. To convert to nmol/L, multiply ng/mL by 0.33.
Comments:
This assay may be significantly impacted by high-dose biotin (>5 mg dose) taken within previous 12 hours. High concentrations of biotin may lead to falsely decreased results. These concentrations may be found in patients taking over-the-counter supplements with biotin content much higher than nutritional requirements for biotin. Specimens should not be collected until at least 12 hours after the last dose.

Fasting sample preferred.
Test Limitations:
Hemolysis: No significant interference up to an H index of 300 (approximate hemoglobin concentration: 300 mg/dL).

Lipemia: No significant interference up to an L index of 2000 (approximate triglycerides concentration: 4000 mg/dL). Note there is poor correlation between turbidity and triglyceride concentration.

Icterus: No significant interference up to an I index of 50 (approximate conjugated and unconjugated bilirubin concentration: 50 mg/dL).
Methodology:
Electrochemiluminescence Immunoassay
CPT Code:
83519
 
See Additional Information:
Biotin Interference with Immunoassays