May be of value in the assessment of residual pancreatic function in insulin treated diabetics, diagnosis of insulinoma and for investigation for covert insulin administration. It is suggested that an endocrinologist be consulted.
Pre-Testing Requirements - Fasted overnight. Fasting and 2 hour postprandial plasma glucose levels are useful INITIAL screening tests. Please send these results with C-peptide.
Transport to lab on water/ice slurry if haemolysis likely.
Ambient (8 - 24 degrees Celsius)
Transport to lab ambient for up to 5 days if no hemolysis, otherwise frozen.
A deficient plasma C-peptide response to a defined protein/carbohydrate meal is seen in diabetes mellitus. For most clinical purposes the 24-hr urinary C-peptide excretion gives an adequate and more convenient index of endogenous pancreatic function. Excessive urinary C-peptide excretion is seen in insulinoma. Deficient C-peptide excretion is seen in diabetes mellitus and in hypoglycaemia due to the administration of exogenous insulin.
350 – 750 pmol/L (fasting, BMI <25)
Roche Cobas e411
$40.81 (Exclusive of GST)
Measure glucose at the same time.
At room temperature, C-peptide is sensitive to hemolysis, and the rate of C-peptide loss increases with the degree of hemolysis. For example, at a level of 0.8g Hb/L, 10% of C-peptide is lost after 24 hours at room temperature.
C-peptide in plasma is not stable long-term at -20o. Loss is of the order of 2% per month. Stable at -40o or lower.