Abstract
IgG4 measurement was adopted in the new version of Japanese diagnostic criteria for autoimmune pancreatitis proposed in 2006. The sensitivity and specificity of IgG4 for the diagnosis of autoimmune pancreatitis were 80% and 98%. However, IgG4 is not pathognomonic, because a high serum IgG4 concentration was also associated with a few cases of pancreatic cancer. The sensitivity and specificity of IgG were 80% and 98%, respectively. Sensitivities of disease non-specific autoantibodies of anti-nuclear antigen (ANA) and rheumatoid factor (RF) were 60% and 20%∼30%, respectively. Disease specific autoantibodies of anti-SSA, anti-SSB and anti-mitochondrial antibody showed negative results. A comparative study using identical sera showed the best diagnostic result for IgG4. Additional measurements of ANA and RF further improved the results of IgG4, though combined measurement of IgG4 and IgG showed no advantage. Because IgG4 measurement in Japan is costly, it would be useful to measure IgG combined with ANA and RF for the diagnosis of autoimmune pancreatitis.
