Analytical and clinical comparison between two different chemiluminescent enzyme immunoassays for the measurement of C-peptide in serum

摘要

BACKGROUND: Connecting peptide (C-peptide) is the cleavage product of proinsulin and is released in blood in equimolar amounts to insulin. Compared to the latter, C-peptide has a longer plasma half-life and is less affected by hemolysis, therefore could be a useful marker of insulin production. We aimed to compare the analytical performance of two different chemiluminescent enzyme immunoassays (CLEIA) for the measurement of C-peptide in serum. METHODS: Overall, 106 subjects (median age: 51 [20-75]; M/F: 72/34) with available serum samples were included in the study; 14 (13.2%) had a diagnosis of impaired fasting glucose (IFG) and 28 (26.4%) of type 2 diabetes mellitus (T2DM). C-peptide was measured in serum by Elecsys? C-peptide (Roche, Mannheim, Germany) and by Lumipulse? c-Peptide (Fujirebio, Tokyo, Japan) CLEIAs. RESULTS: Median C-peptide levels measured by Elecsys? and Lumipulse? were comparable in our study cohort (2.6 [0.3-13.3] ng/mL vs. 2.54 (0.01-10.50) ng/mL, respectively; P=0.665). No random differences were observed between the two methods; the analytical agreement between both was satisfactory. C-peptide serum values were strongly correlated to insulin concentration (r_s=0.626, P0.7 for the discrimination between patients with and without overt T2DM. CONCLUSIONS: The Elecsys? and Lumipulse? C-peptide CLEIAs showed an adequate analytical agreement. The measurement of serum C-peptide may represent a valid surrogate of pancreatic β-cell function with a potential useful application in the clinical setting.