Clinical Significance of Immunoglobulin G4

IgG4 is a class of immunoglobulins whose normal levels in most adults range between 1.0 and 4.5 g/L. When certain diseases or immune system abnormalities are present, IgG4 levels can significantly increase, a condition commonly known as IgG4-related disease (IgG4-RD). The most common manifestation of IgG4-RD is inflammatory tissue proliferation, which can affect multiple organs and tissues, including the kidneys, head and neck, thorax, liver, gastrointestinal tract, breasts, bladder, blood vessels, and nervous system. Therefore, accurate diagnosis of IgG4-RD is crucial to enable physicians to implement appropriate treatment strategies. Furthermore, precise treatment for patients with elevated IgG4 levels can alleviate suffering and improve outcomes.