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Blood Sciences

Blood Test Information

minimum sample volume required ~ 4ml

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Test Code: CPE

Tube type: EDTA

Special instructions
Send separate Glucose (fluoride) sample.
Sample must be received in lab within 24 hours of collection.

Sent away to Bristol Royal Infirmary

Reference range
240 - 1500 (In fasted but but hypoglycaemic individuals)


Linked to

Turnaround Time
7 days

Department: Biochemistry

Clinical Application
C-peptide is released at the time of endogenous insulin secretion. Discrepancy between c-peptide and insulin measurements can help in the differential diagnosis of hypoglycaemia (low c-peptide values seen in factitious exogenous insulin-induced disorder.

C-peptide may also be measured when querying if the patient is a type 1 or 2

Interpretation of random / post prandial C-peptide for investigation of patients with established diabetes mellitus (>3 years since onset)
Values greater than 300 pmol/L indicate substantial insulin secretion and is associated with type 2 DM, MODY and absence of absolute insulin requirement.
Values between 100 and 300 pmol/L indicate intermediate insulin secretion
C-peptide results less than 100 pmol/L indicate severe insulin deficiency and individuals should be manage as type 1 DM

During a hypoglycaemic episode (glucose ≤2.6 mmol/L) , a C-Peptide concentration greater than 150 pmol/L is inappropriately raised and is highly suggestive of hyperinsulinism. C-peptide is considered appropriately suppressed if less than 50 pmol/L. Indeterminate values i.e. 50 - 150 pmol/L require measurement of beta hydroxybutyrate to determine if hyperinsulinism is present.


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