Test Overview
Test Methodology

Chemiluminescence

Test Usage

Evaluate residual beta cell function in patients with diabetes mellitus treated with insulin, low in instances of surreptitious injection of insulin, elevated in insulin autoimmune hypoglycemia, workup of hypoglycemia and to aid in the diagnosis of insulinoma with glucose and insulin assays.

Reference Range *

1.0-5.2 ng/ml (fasting)

Test Details
Days Set Up
Monday, Wednesday, Friday
Analytic Time

8 hours

Soft Order Code
CPEP
MiChart Code
C-Peptide
Synonyms
  • Connecting Peptide
  • C-Peptide Reactivity
  • CPR
  • Endogenous Insulin, Marker
  • Insulin C-Peptide
  • C PEPTIDE
  • CPEP
  • C-PEPTIDE
Laboratory
Chemical Pathology
Section
Special Chemistry
Specimen Requirements
Collection Instructions

Collect specimen in green top tube from a fasting patient (red top tube is acceptable). Place specimen on ice immediately after collection and keep cold until ready to aliquot. Centrifuge, aliquot plasma into a plastic vial and freeze within 1 hour of collection.

Special Handling

Fasting specimen. Place on ice immediately. Must arrive in lab or aliquot and freeze within 2 hours.

Alternate Specimen
SST (not preferred). Heparinized plasma transported on ice is the preferred collection and handling; specimens must be assayed or aliquotted and frozen within 2 hours of collection. If CD personnel are unsure of a sample's validity for c-peptide testing, please consult with chemistry staff. [10/05]
Normal Volume
1 mL plasma
Minimum Volume
0.5 mL plasma
Billing
CPT Code
84681
Fee Code
23359
LOINC
Z15-8