C-Peptide
Label Mnemonic: CPEP
Epic code: LAB521
Order form: Laboratory Requisition
Supply order: Supply Order Form
Billing: Billing Policies
CPT code: 83519
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
Sample Processing:
Centrifuge at a speed and time necessary to get barrier separation of plasma/serum and cells within 1 hour of collection. Send specimen in original tube. Do Not transfer to another tube.
Each sample must be labeled with at least TWO full patient identifiers (First/Last Name & DOB are sufficient for non-UIHC affiliated clients) to avoid sample rejection/delays.
Sample Storage:
Refrigerate.
All sample storage requirements are intended for delivery to UIHC within 24 hours of collection for testing. If samples won't arrive in this time period, please call the UIHC Core Lab for alternative storage/shipping instructions (319-356-3527).
Transport Instructions:
Place labeled specimen into zip-lock type biohazard bag; seal bag.
Place completed requisition into outside pocket of bag.
Transport in cooler with refrigerated coolant packs.
CPT Code:
83519
 
See Additional Information:
Biotin Interference with Immunoassays