Value of serum IgG4 in the diagnosis of IgG4-related disease and in differentiation from rheumatic diseases and other diseases

• DOI: 10.1007/s10165-011-0532-6
• Publication Date: 2011-09-28T01:29:05Z
• Authors: Motohisa Yamamoto; Tetsuya Tabeya; Yasuyoshi Naishiro; Hidetaka Yajima; Keisuke Ishigami; Yui Shimizu; Mikiko Obara; Chisako Suzuki; Kentaro Yamashita; Hiroyuki Yamamoto; Toshiaki Hayashi; Shigeru Sasaki; Toshiaki Sugaya; Tadao Ishida; Ken-ichi Takano; Tetsuo Himi; Yasuo Suzuki; Norihiro Nishimoto; Saho Honda; Hiroki Takahashi; Kohzoh Imai; Yasuhisa Shinomura
• Keywords: Adult; Male; Churg-Strauss Syndrome; Mikulicz' Disease; Autoimmune Diseases; 3. Good health; Diagnosis, Differential; 03 medical and health sciences; 0302 clinical medicine; Pancreatitis; Immunoglobulin G; Rheumatic Diseases; Humans; Female

IgG4-related disease (IgG4-RD) is a novel disease entity that includes Mikulicz's disease, autoimmune pancreatitis (AIP), and many other conditions. It is characterized by elevated serum IgG4 levels and abundant IgG4-bearing plasmacyte infiltration of involved organs. We postulated that high levels of serum IgG4 would comprise a useful diagnostic tool, but little information is available about IgG4 in conditions other than IgG4-RD, including rheumatic diseases. Several reports have described cutoff values for serum IgG4 when diagnosing IgG4-RD, but these studies mostly used 135 mg/dL in AIP to differentiate from pancreatic cancer instead of rheumatic and other common diseases. There is no evidence for a cutoff serum IgG4 level of 135 mg/dL for rheumatic diseases and common diseases that are often complicated with rheumatic diseases. The aim of this work was to re-evaluate the usual cutoff serum IgG4 value in AIP (135 mg/dL) that is used to diagnose whole IgG4-RD in the setting of a rheumatic clinic by measuring serum IgG4 levels in IgG4-RD and various disorders. We therefore constructed ROC curves of serum IgG4 levels in 418 patients who attended Sapporo Medical University Hospital due to IgG4-RD and various rheumatic and common disorders. The optimal cut-off value of serum IgG4 for a diagnosis of IgG4-RD was 144 mg/dL, and the sensitivity and specificity were 95.10 and 90.76%, respectively. Levels of serum IgG4 were elevated in IgG4-RD, Churg-Strauss syndrome, multicentric Castleman's disease, eosinophilic disorders, and in some patients with rheumatoid arthritis, systemic sclerosis, chronic hepatitis, and liver cirrhosis. The usual cut-off value of 135 mg/dL in AIP is useful for diagnosing whole IgG4-RD, but high levels of serum IgG4 are sometimes observed in not only IgG4-RD but also other rheumatic and common diseases.