Expression Of Serum IgG4 In Patients With Hepatobiliary And Pancreatic Diseases

Objective: To investigate the expression and clinical significance of serum IgG4 in hepatobiliary and pancreatic diseases.Methods: A retrospective analysis was conducted based on the clinical data from patients with hepatobiliary and pancreatic diseases in the First Affiliated Hospital of Fujian Medical University between January 2016 and May 2018.Serum IgG4 levels were compared between patients with IgG4-related diseases(IgG4-RD)and non-IgG4-RD by non-parametric test and the potential factors affecting serum IgG4 levels were explored.The area under receiver operating characteristics(AUROC)curve was employed to explore the best cutoff value of serum IgG4 level for the diagnosis of IgG4-RD.Results: A total of 610 patients were enrolled,including 10 cases in the IgG4-RD group and 600 cases in the non-IgG4-RD group.The median serum IgG4 levels in IgG4-RD group and non-IgG4-RD group were significantly different [10.95(7.42-12.60)g/L vs 0.62(0.35-1.11)g/L,Z=-5.267,P<0.001].According to the diagnostic threshold of IgG4 recommended by guidelines,112(18.36%)patients in overall population had an elevated IgG4 level >1.35g/L,including 10 in IgG4-RD group and 102 in non-IgG4-RD group.When a cutoff value of 4.68 g/L was set,the AUROC for serum IgG4 in differentiating IgG4-RD from non-IgG4-RD was 0.985(95% CI=0.956-1.000,P < 0.001).The sensitivity,specificity and Youden index were 90%,100% and 0.90,respectively.There was a significant correlation between serum IgG4 levels and age,IgG,IgE,TBIL,ALP,ALB,GLO,E%(P<0.05).Serum IgG4 levels increased with age.In patients with the age under 25 years,the average serum IgG4 level was 0.53(0.28-0.87)g/L,while in the patients with older age(?70 years old),IgG4 level was 0.76(0.41-1.43)g/L.Serum IgG4 levels in men were significantly higher than in women [0.73(0.41-1.31)g/L vs 0.55(0.30-0.88)g/L,Z=-4.098,P< 0.001].According to the main diagnostic information of the subjects,a subgroup analysis of 600 patients in the non-IgG4-RD group was carried correspondingly.As a result,102 patients were detected with a high serum IgG4 level of 1.35 g/L,including 16 patients with hepatobiliary and pancreatic tumors(16.67%),10 cases with autoimmune liver disease(16.13%),28 cases with liver disease of definite etiology(16.97%),20 cases with unexplained liver disease(24.10%),15 cases with non-neoplastic biliary disease(16.30%),13 cases of non-neoplastic pancreatic disease(12.75%),the proportion of patients with serum IgG4 levels and elevated serum IgG4 was not significantly different between the above groups(P>0.05).Then a subgroup analysis of patients with autoimmune liver disease,The serum IgG4 levels in patients with AIH was 0.72(0.58-1.13)g/L,higher than in PBC patients [0.58(0.32-0.83)g/L] and in patients with overlap syndrome(AIH+PBC)[0.48(0.34-0.81)g/L],however there ware no statistically significant differences(P>0.05).Conclusions: Elevated serum IgG4 levels are observed in non-IgG4-RD patients.Serum IgG4 levels in men were significantly higher than in women.The serum IgG4 levels are significantly correlated with age.Moreover,a higher diagnostic cutoff(4.68g/L)may help to improve the specificity and accuracy for diagnosis of IgG4-RD.