C-Peptide

Test Code

CPEP

Quest Code

372

Alias/See Also

C-Peptide, Insulin
CPEP
C PEPTIDE
C Peptide

CPT Codes
84681

Preferred Specimen

1 mL serum

Patient Preparation
Patients should fast 12 hours prior to collection.

Minimum Volume

0.5 mL

Transport Container

Plastic screw-cap vial

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 4 days
Refrigerated: 7 days
Frozen: 7 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Plasma • Gross hemolysis

Methodology
Immunoassay (IA)

Setup Schedule

Set up: Mon-Sat a.m.; Report available: Next day

Reference Range

0.80-3.85 ng/mL

Clinical Significance

C-Peptide is useful in the evaluation of pancreatic beta cell function (e.g., helping distinguish type 1 from type 2 diabetes mellitus, or monitoring patients who have received islet cell or pancreatic transplants) and for determining the source of insulin in patients with hyperinsulinemic hypoglycemia (e.g., distinguishing insulin-secreting tumors from exogenous insulin administration). It is also sometimes measured as an additional means (more resistant to hemolysis than is insulin itself) for evaluating glucose tolerance tests.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

Last Updated: June 19, 2020

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.