Laboratory: Clinical Biochemistry  (SPECIAL CHEMISTRY)
Test Name:
C-PEPTIDE (CPEPTIDE) - (S)
Test Code: CP
Clinical Information:
Test Indications: Useful for:

1)     Hypoglycemia workup (factitious hypoglycemia, insulinoma)

2)      Assessment of insulin reserve endogenous insulin secretory reserve, monitoring pancreatic and islet cell transplant function, monitoring immunomodulatory therapy in type 1 diabetes)

 

Ordering is available only for physicians approved to use the Specialized Endocrinology Requisition See F10-50-45D Approved Physicians for Specialist Endocrinology Requisition


Patient preparation instructions: Fasting 8-12 hours.

Non-fasting specimen may be used to evaluate pancreatic reserve at the discretion of the physician.


 
Collection Devices:
Red top no gel serum tubes are also acceptable.
Specimen Required:


Serum: 1.0 mL
Pediatric Serum: 0.3 mL

Collection Information: If ordering Insulin as well, submit separate frozen specimen for each test.

Special Processing: Separate plasma/serum from cells immediately (<60 min) and freeze.

Specimen Stability:

Ambient: Not stable

Refrigerated: 24 hours

Frozen:  many months at -20C (avoid repeat freeze-thaw cycles)
Referral:

Shipping & Storage: Serum must be transferred to an aliquot tube and stored/shipped frozen.

 

Thawed samples are not suitable for testing.

 

See #110-10-05 Serum / Plasma Separation Procedure & Transport


Testing Laboratory (MB): Send specimen to Health Sciences Centre - MS5
Requisition:
Reference Values:
Reference Intervals: 260 - 1390 pmol/L

 

Reference intervals are applicable to 12h fasting collection.


Method of Analysis: DiaSorin Chemiluminescence
Availability:
Within 1 Week
Orderable by physicians specializing in endocrinology -authorized physicians only.
See Also:
More Information:
Interpretation & Assay Interferences: The assay is not affected by concentrations of bilirubin up to 12.5 mg/dL, hemoglobin up to 5000 mg/dL, or triglycerides up to 1250 mg/dL.

 

Patients with renal malfunction show elevated C-peptide values.

Food intake or therapy with ß-cell stimulating drugs (e.g. corticosteroids) increase C-peptide secretion.

 

Although HAMA-neutralizing agents are added, extremely high HAMA (human anti-mouse antibodies) concentrations may occasionally influence results.


References: Hörber S, Orth M, Fritsche A, Peter A. Comparability of C-Peptide Measurements - Current Status and Clinical Relevance. Exp Clin Endocrinol Diabetes. 2023 Mar;131(3):173-178. doi: 10.1055/a-1998-6889.