Radioimmunoassay of human calcitonin using labeled [Asu1,7]-human calcitonin analogue.

Abstract

Application of synthetic human calcitonin analogue ([Asu^{1, 7}]-hCT) was attempted, since it is chemically more stable than native hCT.[Asu^{1, 7}]-hCT was successfully labeled with ¹²⁵I to a specific activity ranging from 410 to 540μCi/μg. Sensitivity, recovery and reproducibility of the assay system using ¹²⁵I-labeled [Asu^{l, 7}]-hCT analogue, standard synthetic hCT and its antibodies, were 49pg/ml, 99.8±4%, and 7.95%(C. V. within assay) or 21.9%(C. V. between assays), respectively. The dilution curve of the sera obtained from patients with medullary carcinoma paralled well with the standard curve. ¹²⁵I-labeled [Asu^{l, 7}]-hCT analogue can be used for routine radioimmunoassay of hCT.