C Peptide (Insulin C-Peptide)
Code:
CEPEP
Sample Type:
EDTA plasma (Purple Top) or Serum (Gold Top)
Random urine – plain, no preservative
Minimum volume: 1 mL
Ref Ranges/Units:
Interpretation depends on the clinical context and glucose level. Please contact the duty biochemist if advice is required.
Turnaround:
Within 1-2 weeks
Stability:
4 hours at 15‐25°C
24 hours at 2‐8°C
30 days at ‐20°C
Freeze only once
Special Precautions/Comments:
EDTA plasma or urine are preferred sample types as they are more stable.
If serum sample, send to laboratory immediately for separation and freezing.
Additional Information:
Proinsulin is cleaved to form insulin and C-peptide in equimolar concentrations in pancreatic beta-cells. C-peptide has a longer half-life than insulin, and therefore can be used as a more reliable marker of endogenous insulin production. A paired plasma glucose sample is useful for interpretation.
Measurement of C-peptide is mainly used in the investigation of hypoglycaemia or to differentiate between insulin-deficient diabetes (type 1) and insulin-resistant diabetes (type 2). It can also be useful in assessing the need to initiate insulin therapy in patients with type 2 diabetes.
South of Tyne & Wear Pathology Centre
