Relationship between pancreatic and/or extrapancreatic lesions and serum IgG and IgG4 levels in IgG4-related diseases

Objective: We aimed to investigate the relationship between the number of involved organs or regions and serum immunoglobulin G (IgG) and immunoglobulin G4 (IgG4) levels. Methods: The number of pancreatic and/or extrapancreatic lesions and serum IgG and IgG4 levels were examined by groups in 46 patients with IgG4-related diseases at diagnosis prior to the initiation of steroid treatment: group A (one region involved, n=7), group B (two regions involved, n=11), group C (three regions involved, n=12), group D (four regions involved, n=9) and group E (five to seven regions involved, n=7). Results: Both serum IgG and IgG4 levels increased with the number of inflamed regions. Mean serum IgG levels were 15.11, 18.65, 20.92, 23.29 and 30.98g/L while the mean IgG4 levels were 3.99, 4.70, 4.70, 9.86 and 16.49g/L in group A, B, C, D and E, respectively. Regression analysis also suggested that IgG4 was positively correlated with the number of regions involved. Additionally, serum IgG4 was higher in patients with multiple lesions when accompanied by sclerosing sialadenitis. Conclusion: Patients having IgG4-related disease with high serum IgG and IgG4 levels should be systematically examined for involved lesions.