Calbiotech C-Peptide ELISA

SUMMARY AND EXPLANATION 
Human C-Peptide has a molecular mass of approximately 3000 daltons. C-Peptide has no metabolic function. However, since C-Peptide and insulin are secreted in equimolar amounts, the immunoassay of CPeptide permits the quantitation of insulin secretion. This is the reason for the clinical interest of serum or plasma determinations of C-Peptide. Moreover, C-Peptide measurement has several advantages over immunoassays of insulin. The half-life of C-Peptide in the circulation is between two and five times longer than that of insulin. Therefore, C-Peptide levels are a more stable indicator of insulin secretion than the more rapidly changing levels of insulin. A very clear practical advantage of C-Peptide measurement arising from its relative metabolic inertness as compared to insulin is that C-Peptide levels in peripheral venous blood are about 5-6 times greater than insulin levels. Also, relative to an insulin assay, the C-Peptide assay's advantage is its ability to distinguish endogenous from injected insulin. C-Peptide has also been measured as an additional means for evaluating glucose tolerance and glibenclamide glucose tests. CPeptide levels are in many ways a better measurement of endogenous insulin secretion than peripheral insulin levels. C-Peptide may be measured in either blood or urine. With improved sensitive C-Peptide immunoassays, it is now possible to measure C-Peptide values at extremely low levels. The clinical indications for C-Peptide measurement include diagnosis of insulinoma and differentiation from factitious hypoglycemia, follow-up of pancreatectomy, and evaluation of viability of islet cell transplants. Recently, these indications have been dramatically expanded to permit evaluation of insulin dependence in maturity onset diabetes mellitus.

PRINCIPLE OF THE TEST 
The C-peptide is a solid phase direct sandwich ELISA method. The samples and conjugate reagent (anti C-peptide biotin & HRP) are added to the wells coated with Streptavidin. C-peptide in the patient’s serum binds to the matched pair Abs, forming a sandwich complex and simultaneously the complex is being immobilized on the plate through streptavidin-biotin interactions. Unbound proteins and HRP conjugate is washed off by wash buffer. Upon the addition of the substrate, the intensity of color is proportional to the concentration of C-peptide in the samples. A standard curve is prepared relating color intensity to the concentration of the C-Peptide.

STORAGE AND STABILITY 
1. Store the kit at 2 – 8°C. 
2. Keep microwells sealed in a dry bag with desiccants. 
3. The reagents are stable until expiration of the kit. 
4. Do not expose test reagents to heat, sun or strong light