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HelpTest Code CPEP C-Peptide, Serum
Reporting Name
C-Peptide, SUseful For
Diagnostic workup of hypoglycemia:
-Diagnosis of factitious hypoglycemia due to surreptitious administration of insulin
-Evaluation of possible insulinoma
-Surrogate measure for the absence or presence of physiological suppressibility of endogenous insulin secretion during diagnostic insulin-induced hypoglycemia (C-peptide suppression test)
Assessing insulin secretory reserve in selected diabetic patients (as listed below) who either have insulin autoantibodies or who are receiving insulin therapy:
-Assessing residual endogenous insulin secretory reserve
-Monitoring pancreatic and islet cell transplant function
-Monitoring immunomodulatory therapy aimed at slowing progression of preclinical, or very early stage type 1 diabetes mellitus
Performing Laboratory
Mayo Medical Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Patient Preparation: 12 hours before this test do not take multivitamins or dietary supplements containing biotin or vitamin B7, which are commonly found in hair, skin, and nail supplements and multivitamins.
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions:
1. Fasting: 8 hours
2. Serum gel tubes should be centrifuged within 2 hours of collection.
3. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.
Specimen Minimum Volume
0.4 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Frozen (preferred) | 30 days |
| Refrigerated | 7 days |
Reference Values
1.1-4.4 ng/mL
Reference intervals have not been formally verified in-house for pediatric patients. The published literature indicates that reference intervals for adult and pediatric patients are comparable.
Day(s) and Time(s) Performed
Monday through Friday; 5 a.m.-12 a.m., Saturday; 6 a.m.-6 p.m.
Test Classification
This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
84681
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CPR | C-Peptide, S | 1986-9 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| CRPN | C-Peptide, S | 1986-9 |
Reject Due To
|
Hemolysis |
Mild OK; Gross reject |
|
Lipemia |
Mild OK; Gross OK |
|
Icterus |
NA |
|
Other |
Autopsy specimen |
Method Name
Electrochemiluminescence Immunoassay
Forms
If not ordering electronically, complete, print, and send a General Request Form (T239) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/general-request-form.pdf).