Serum levels of IgG and IgG4 in Hashimoto thyroiditis

Abstract

Although IgG4-related disease is characterized by extensive infiltration of IgG4-positive plasma cells and lymphocytes of various organs, the details of this systemic disease are still unclear. We screened serum total IgG levels in the patients with Hashimoto thyroiditis (HT) to illustrate the prevalence of IgG4-related thyroiditis in HT. Twenty-four of 94 patients with HT (25.5%) had elevated serum IgG levels and their serum IgG4 was measured. Five of the 24 cases had more than 135 mg/dL of IgG4, which is the serum criterion of IgG4-related disease. One was a female patient who was initially treated as Graves' disease and rapidly developed a firm goiter and hypothyroidism. The biopsy of her thyroid gland revealed that follicular cells were atrophic with squamous metaplasia, replaced with fibrosis, which was compatible with the fibrous variant of HT. Immunohistochemical examination revealed diffuse infiltration of IgG4-positive plasma cells, and the serum IgG4 level was 179 mg/dL. The levels of IgG and IgG4 were positively correlated with the titers of anti-thyroglobulin antibody or anti-thyroid peroxidase antibody. In conclusion, at least a small portion of patients with HT with high titers of anti-thyroid antibodies may overlap the IgG4-related thyroiditis.

Distribution of serum immunoglobulin G4 levels in Hashimoto’s thyroiditis and clinical features of Hashimoto’s thyroiditis with elevated serum immunoglobulin G4 levels

“…Thus, patient background differed between the studies. An association between IgG4 thyroiditis and male predominance or diffuse hypoechogenicity has also been suggested in other reports [7,14]. Consistent with those studies, ultrasonography revealed that hypoechoic areas were larger in the elevated IgG4 group than in the non-elevated IgG4 group in our prospective study.…”

“…Among the HT patients in our study, 4.0% had elevated serum IgG4 levels; this proportion was higher in a previous study conducted by Kawashima et al (20.8%) [14]. This difference can be attributed in part to the method of screening patients: although Kawashima et al excluded patients with normal serum IgG levels, we selected all patients with HT prospectively; consequently, we included patients with early-stage HT.…”

Zaburzenia tarczycy związane z immunoglobuliną G4 — wyzwanie diagnostyczne i wyniki kliniczne

“…However, in contrast to the female preponderance of autoimmune (Hashimoto's) thyroiditis, there is no sex predilection for IgG4RTD. It is believed to occur equally among males and females [1,2]. Recent reports have also suggested that a small fraction of Graves' disease patients also have elevated IgG4 levels with some features suggestive of IgG4TD [21,22].…”

“…IgG4-related disease per se as an entity was recognised only in 2001, with autoimmune pancreatitis being the prototype organ involvement [1]. Thyroid involvement in IgG4RD is rare, believed to occur in < 4% of cases [1,2].…”

Clinicopathological features of Riedel&rsquo;s thyroiditis associated with IgG4-related disease in Japan

“…An association between thyroid diseases such as Graves' disease, Hashimioto's thyroiditis, and RT and IgG4-related disease (IgG4-RD) has recently been reported [11][12][13][14][15]. Patients with IgG4-RD exhibit elevated serum IgG4 levels, IgG4-positive plasma cells, and tissue fibrosis and organ dysfunction caused by lymphocyte infiltration into multiple organs [16,17].…”