Quantitative analysis of elevated serum Golgi protein-73 expression in patients with liver diseases

Background: Golgi protein-73 (GP73) is a newly identified candidate serum marker for liver diseases. The utility of this biomarker remains limited, largely due to the lack of quantitative information. The aims of this study were to quantify serum GP73 (sGP73) in healthy individuals and in patients with liver diseases, and to validate sGP73 as a biomarker for early diagnosis of liver disease. Methods: Recombinant GP73 was used to generate monoclonal (mAb) and polyclonal antibodies (pAb). Using these antibodies in a quantitative enzyme-linked immunosorbent assay, GP73 was measured in serum from 263 patients with various forms of liver and other diseases. Results: The median sGP73 in patients with liver disease was significantly higher (P < 0.001) than in healthy individuals and in patients with other diseases. When sGP73 was used to detect liver disease, it had a sensitivity of 82% and a specificity of 80% at the optimal cut-off value of 85.5 mu g/L. The area under the receiver-operating characteristic curve was 0.9. Conclusion: sGP73 concentration in patients with liver disease was three-fold higher than in healthy individuals. However, sGP73 concentrations did not differ significantly between patients from each liver disease group. Furthermore, sGP73 was not significantly elevated in patients with diseases other than liver disease compared with healthy individuals. These results suggest that sGP73 may be used as a serum marker for the diagnosis of liver disease.