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Test Code CPTDE C-Peptide

Important Note

This test may be affected by biotin interference. Patients on high dose biotin (5mg/day or more) should not have samples drawn until at least 24 hours after the last biotin administration.

Specimen and Container/Tube

Specimen Type: Serum

Preferred Specimen: Red Top

Other Acceptable specimens: Serum/Gold Top, Plasma/Li-Heparin Mint Green Top, Plasma/Lavendar K2 Top, Plasma/Lavendar K3 Top

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

  • Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples should be centrifuged within 2 hours of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into a plastic tubes containing a minimum of 0.2 mL of specimen.
  • Samples must then be sent refrigerated at 2-8oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours

Reference Values

Test

Age

Sex

Reference Range

CPTDE

All

All

0.3 - 2.35 pmol/mL

Note: Reference ranges are based on i-house studies performed at the University of Chicago Medicine by the Clinical Chemistry Laboratories per the Roche cobas 8000 modular analyzer series e801 System Installation Workbook and the e801 C-Peptide product insert.

Critical Values

Analyte

Unit

Low

High

Age

N/A

N/A

N/A

N/A

N/A

CPT Codes

84681

LOINC Codes

14633-2

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL

Specimen Stability

Storage Temperature

Stability

Room Temperature

4 hours

Refrigerated

24 hours

Frozen

1 month

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Test Components

C-Peptide

Clinical Indications

Aid in the diagnosis and treatment of patients with abnormal insulin secretion.

Methodology

Electrochemiluminescence immunoassay (ECLIA) (Roche Diagnostics)

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
  • Measurements of C-peptide, insulin and glucose are used as an aid in differential diagnosis of hypoglycemia (factitious hypoglycemia caused by hyperinsulinism) to ensure an appropriate management and therapy of the patients.
  • C-peptide is measured basally, after fasting and after stimulation and supression tests. Due to high prevalence of endogenous anti-insulin antibodies C-peptide concentrations reflect the endogenous pancreatic insulin secretion more reliably in insulin-treated diabetics than the levels of insulin itself. Measurements of C-peptide may therefore be an aid in assessment of a residual β-cell function in the early stages of type 1 diabetes mellitus and for the differential diagnosis of latent autoimmune diabetes of adults (LADA) and type 2 diabetes.
  • C-peptide measurements are also used to assess the sucess of islet transplantation and for monitoring after pancreatectomy.
  • Elevated C-peptide levels may also result from renal insufficiency and obesity.

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: Not available as STAT test

Routine Turnaround Time: up to 4 hours

Testing Schedule:  24/7

Synonyms/Keyword Search

C Peptide Connecting Peptide of Insulin

Connecting Peptide of Insulin

Last Review Date

8/19/2024