Test Center

My Recent Searches

  • No Recent Search.

My Tests Viewed

  • No Test Viewed.
  • Ordering Info


Test Code


CPT Code(s)


Patient Preparation

Fasting specimen

Preferred Specimen(s)

1 mL frozen serum

Minimum Volume

0.4 mL

Alternative Specimen(s)

Refrigerated serum (within stability) • Frozen sodium heparin (green-top tube) plasma • Refrigerated sodium heparin (green-top tube) plasma (within stability)

Specimen Container

Plastic screw-cap vial

Transport Temperature


Specimen Stability

Room temperature: 24 hours
Refrigerated: 7 days
Frozen -20° C: 28 days
Frozen -70° C: 12 months

Reject Criteria

Room temperature samples received more than 24 hours after collection



Performing Laboratory

Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

Setup Schedule

Monday-Friday Evening; Report available: Next Day

Reference Range(s)

0.80-3.10 ng/mL

Clinical Significance

C-Peptide is useful in the evaluation of pancreatic beta cell function and for determining the source of insulin in patients with hyperinsulinemic hypoglycemia.

LOINC®' Code(s)

The Result and LOINC information listed below should not be used for electronic interface maintenance with Quest Diagnostics. Please contact the Quest Diagnostics Connectivity Help Desk for more information at 800-697-9302.

NOTE: The codes listed in the table below are not orderable Test Codes.

Result NameLOINC CodeComponent Name
372C-Peptide1986-9C peptide

Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.

The CPT codes provided 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 payer being billed.

LOINC assignment is based on a combination of test attributes, including the method used by the performing laboratory. For tests not performed by Quest Diagnostics, codes are assigned by the performing laboratory.

* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.