C-Peptide radioimmunoassay (RIA) is an invaluable aid in diagnosis of diabetes, insulinoma and hypoglycaemia. An RIA for C-peptide was developed by using a polyclonal antibody for human C-peptide raised in rabbits and validated using human serum samples. Tyrosyated C-peptide was radioiodinated to a specific activity of around 283 µCi/µg by conventional chloramine-T method. The detection limit of the assay (90% binding) was 0.43 ng/mL and the ED50 value was 8.5 ng/mL. The assay with the standard range of 0.3–18 ng/mL and low non-specific binding provide superior assay features. Separation of the bound from free complex was carried out using 22% polyethylene glycol. Intra-assay and inter-assay variations were found to be < 11.5% along with analytical recovery of 90–104%. No cross reactivity was observed with proinsulin, glucagon, somatostatin, insulin and pancreatic polypeptide.The developed assay can be used for the routine analysis of clinical samples.

中文翻译：

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用于估计人血清中 C 肽的放射免疫测定法的发展

C 肽放射免疫分析 (RIA) 是诊断糖尿病、胰岛素瘤和低血糖的宝贵辅助手段。C 肽的 RIA 是通过使用多克隆抗体开发的，用于在兔中培养的人 C 肽，并使用人血清样本进行验证。通过常规氯胺-T 方法将酪氨酸化 C 肽放射性碘化至约 283 µCi/µg 的比活。该测定的检测限（90% 结合）为 0.43 ng/mL，ED50 值为 8.5 ng/mL。具有 0.3–18 ng/mL 标准范围和低非特异性结合的检测提供了卓越的检测功能。使用 22% 聚乙二醇将结合物与游离复合物分离。发现测定内和测定间变化 < 11.5%，分析回收率为 90-104%。未观察到与胰岛素原、胰高血糖素、生长抑素、