Abstract:

Objective To evaluate the performance of double-antibody sandwich enzyme-linked immunosorbent assay （ELISA）for chromogranin A （CgA）determination. Methods The precision,linearity and limit of determination of CgA determination by double-antibody sandwich ELISA were verified according to the Clinical and Laboratory Standards Institute （CLSI） EP15-A,EP6-A and EP17-A. The accuracy of CgA determination was assessed by manufacturer's quality control materials. A total of 66 neuroendocrine neoplasm patients,41 healthy subjects and 65 disease control patients were enrolled. The CgA levels in the 3 groups were determined,and receiver operating characteristic （ROC） curve was used to compare the efficiency of CgA determination in diagnosing neuroendocrine neoplasm. Results The within-run and between-run coefficients of variation （CV） of CgA determination by double-antibody sandwich ELISA were <14.00% and <8.00%,respectively. For accuracy evaluation,the relative bias was 4.51%,when the mean o. Results was within the indicated range. There was a good linear correlation（Y=0.793X-3.791,r²=0.988） in the range of 8-740 ng/mL. The limit of determination was 7.93 ng/mL. The difference of CgA levels in neuroendocrine neoplasm,healthy control and disease control groups had statistical significance （P<0.000 1）. The area under curve（AUC）of CgA determination in distinguishing healthy subjects and neuroendocrine neoplasm patients was 0.741,when the cut-off value was 47.18 ng/mL. The sensitivity was 78.8%,and the specificity was 68.3%.Conclusions CgA determination by double-antibody sandwich ELISA has good performance in precision,accuracy,linearity and limit of determination,which meets clinical needs. Serum CgA levels increase in patients with neuroendocrine neoplasm. CgA could be a marker for distinguishing healthy subjects and neuroendocrine neoplasm patients.

Key words: Chromogranin A, Neuroendocrine neoplasm, Sensitivity, Specificity, Receiver operating characteristic curve, Area under curve