Serum immunoglobulin G4 levels and Graves' disease phenotype

IgG4 serum levels in Graves' orbitopathy

OBJECTIVE

IgG4-related disease (IgG4-RD) can involve many organs, including thyroid and orbital tissues. A link between IgG4, Graves' disease (GD) and Graves' orbitopathy (GO) has been proposed, but results are conflicting. Here we investigated the possible association between IgG4 and GO.

METHODS

Retrospective investigation in 297 patients with Graves' disease (GD), 152 with GO.

PRIMARY OUTCOME

prevalence of IgG4 ≥ 135 mg/dL (cut-off for IgG4-RD).

SECONDARY OBJECTIVES

(1) serum IgG4 concentrations; (2) IgG4/IgG ratio; (3) prevalence of IgG4/IgG ratio ≥ 8.0%; (4) relationship between IgG4 and eye features; (5) relationship between IgG4 and anti-TSH receptor antibodies (TRAbs).

RESULTS

Because GO patients had lower FT3 concentrations, we evaluated the main objectives in the second and third FT3 quartiles subpopulation, in which there were no relevant differences between patients with (n = 81) or without GO (n = 67) for baseline parameters. Within this population, the prevalence of IgG4 levels ≥ 135 mg/dL did not differ between patients without and with GO (17.9% vs 17.3%). No difference was observed concerning IgG4 concentrations, prevalence of IgG4/IgG ≥ 8.0%, and IgG4/IgG ratio. There was no relationship between IgG4 and eye features and no correlation between IgG4 levels and TRAb was found.

CONCLUSIONS

Our results suggest that, within GD, there is no relationship between serum IgG4 and GO.

Clinical Significance of IgG4 Serum Concentration in Graves' Disease

Elevated immunoglobulin G4 (IgG4) serum antibodies are an important feature of IgG4-related disease. However, IgG4 antibodies can play a role in autoimmune thyroid disorders. In this study, we aimed to evaluate the impact of serum IgG4 levels on clinical features of Graves' disease (GD). We recruited 60 patients with GD (48 patients without thyroid eye disease, 12 patients with moderate-to-severe Graves' orbitopathy [GO], and 25 healthy control subjects). The prevalence of high IgG4 serum concentration was 4.2% among GD patients without GO and 33.33% in patients with moderate-to-severe GO. The group with GO had significantly higher median IgG4 levels (87.9 mg/dL) than the control group (41.2 mg/dL, P = 0.034) and the GD without GO group (30.75 mg/dL, P < 0.001). Patients with thyroid nodules had lower IgG4 levels than patients without thyroid nodules, but the difference was not statistically significant (35.7 [24.8; 41.53] mg/dL vs. 43 [30.1; 92.7] mg/dL, P = 0.064). IgG4 as a diagnostic tool for moderate-to-severe GO had the following parameters: area under the curve (AUC): 0.851 (P < 0.001), at the cut-off value of 49 mg/dL, negative predictive value: 100%, positive predictive value: 48%, sensitivity: 100%, specificity: 73%. There were no significant differences between the high and normal IgG4 groups in thyroid hormones, antithyroid antibodies, and ultrasound features. Serum IgG4 levels are associated with some of the clinical features of GD and can help in the diagnostic process of the disease. More research is needed to better understand the pathophysiology of IgG4 involvement in GD.

High IgG4 serum concentration is associated with active Graves orbitopathy

BACKGROUND

The aim of the study was to evaluate the differences in clinical profile, laboratory parameters, and ophthalmological signs, and symptoms between patients with high IgG4 Graves orbitopathy and patients with normal IgG4 Graves orbitopathy.

METHODS

This was a prospective observational study. We recruited adult patients with Graves Orbitopathy(GO) referred to our clinic for further diagnostics and treatment. Eventually, 60 patients with GO were enrolled in the study. All patients underwent ophthalmological assessment, magnetic resonance imaging (MRI) of the orbits, and laboratory tests, including IgG4 serum concentration measurement. High IgG4 GO was diagnosed if the IgG4 concentration exceeded 135 mg/dl. We used both the clinical activity score (CAS) and magnetic resonance imaging (MRI) to assess the activity of GO. Eventually, active GO was defined according to MRI results.

RESULTS

Among 60 GO patients, 15 (25%) patients had elevated IgG4 levels. Patients in the high IgG4 group had a higher prevalence of active GO by MRI than patients with normal IgG4 (100% vs. 64.44%, P=0.006). They also had a higher eosinophile count in peripheral blood, a lower bilirubin level, a more frequent lower eyelid retraction, and a lower prevalence of glaucoma. There were no statistically significant differences between the groups in CAS. Patients with active GO, had higher median IgG4 level [89.95 (55.48; 171.1) vs 43.45 (32.48; 49.68) mg/dl, P<0.001]. The receiver operating characteristic (ROC) analysis for IgG4 as a marker of active GO revealed the following results: AUC 0.848 for the cut-off value of 54.2 mg/dl, sensitivity 79.5%, specificity 87.5%, positive predictive value 94.6%, negative predictive value 59.1%.

CONCLUSIONS

We demonstrated that IgG4 is a marker of GO activity. Certain differences in the clinical profile of patients with high IgG4 GO, and normal IgG4 GO were observed. More data is needed to establish whether patients with high IgG4 GO are GO patients with particularly active disease or actually represent a distinct clinical entity related to IgG4-Related Disease.

Immunoglobulin G4-Related Thyroid Disease: A Single-Center Experience and Literature Review

BACKGROUND

Immunoglobulin G4 (IgG4)-related disease is an entity that can involve the thyroid gland. The spectrum of IgG4-related thyroid disease (IgG4-RTD) includes Hashimoto thyroiditis (HT) and its fibrotic variant, Riedel thyroiditis, as well as Graves' disease. The early diagnosis of IgG4-RTD is important because it is a medically treatable disease, and a delay in the diagnosis might result in unnecessary surgery. We present a case series of IgG4-RTD with a review of the literature.

METHODS

We retrospectively reviewed the clinical presentation and the radiological and pathological findings of patients diagnosed with IgG4-RTD between 2017 and 2021 at a tertiary medical center in Korea. We also conducted a literature review of IgG4-RTD.

RESULTS

Five patients were diagnosed with IgG4-RTD during the study period. The patients' age ranged from 31 to 76 years, and three patients were men. Most patients visited the clinic for a neck mass, and hypoechogenic nodular lesions were observed on neck ultrasonography. Three patients had IgG4 HT, and two patients had IgG4 Riedel thyroiditis. All patients developed hypothyroidism that necessitated L-thyroxine replacement. The diagnosis of IgG4-RTD was confirmed after a pathological examination of the surgical specimen in the first two cases. However, the early diagnosis was possible after a core needle biopsy in three clinically suspected patients.

CONCLUSION

The diagnosis of IgG4-RTD requires clinical suspicion combined with serology and histological analyses using IgG4 immunostaining. The early diagnosis of IgG4-RTD is difficult; thus, biopsy with IgG4 immunostaining and serum IgG4 measurements will help diagnose patients suspected of having IgG4-RTD.

The characteristics and clinical significance of elevated serum IgG4/IgG levels in patients with Graves' disease

PURPOSE

This study aims to further explore the clinical and laboratory characteristics of patients with GD with high serum IgG4 based on the IgG4/IgG ratio.

METHODS

This study is a prospective observational study. A total of 25 normal controls and 84 people newly diagnosed with GD were enrolled in this study. Taking the IgG4/IgG ratio of 8% as the cutoff value, the experimental groups were further divided into two subgroups: the high IgG4/IgG subgroup and the normal IgG4/IgG subgroup. We evaluated the differences in clinical characteristics and laboratory parameters between the groups.

RESULTS

The IgG4, IgG4/IgG, and IL-17 of the newly diagnosed GD group were significantly higher than those of the normal control group (P < 0.05). The differences in age, IL-1β, IL-17, and eosinophil count between the high IgG4/IgG subgroup and the normal IgG4/IgG subgroup were statistically significant (P < 0.05). After ATD treatment, some patients developed allergies; the high IgG4/IgG subgroup was significantly higher than the normal IgG4/IgG subgroup (χ2 = 4.424, P = 0.035). After 3 months of ATD treatment in patients with GD, the TRAb in the normal IgG4/IgG subgroup were significantly lower than before (P < 0.05), while the difference in the high IgG4/IgG subgroup was not statistically significant (P > 0.05).

CONCLUSIONS

A small portion of patients with GD harbored elevated serum IgG4/IgG levels. They are younger, have higher eosinophils, and are more prone to allergies; also, they have higher levels of cytokines IL-1β and IL-17 and their remission is not easily attained after treatment with ATD; this could be due to the instability of the Th17/Treg cell balance.

Clinical relevance of serum immunoglobulin G4 in glucocorticoid therapy of Graves' ophthalmopathy

OBJECTIVE

Previous study suggested IgG4 levels were associated with the development of Graves' ophthalmopathy (GO). The aims of the present study were to investigate the role of IgG4 levels in glucocorticoid (GC) treatment in GO patients.

DESIGN

69 GO patients were enrolled. Serum thyroid hormones, thyroid antibodies, IgG, IgG4, ophthalmological examinations and orbital MRI were performed. Furthermore, the clinical outcomes (a composite response endpoint including the clinical activity score (CAS), proptosis, vision, intraocular pressure, diplopia and lid width) after high-dose intravenous GC treatment in 32 active moderate-to-severe GO patients were compared.

PATIENTS

69 consecutive patients with GO were asked to participate in the study. 32 of 69 GO patients were treated with high-dose intravenous GCs.

MEASUREMENTS

Measurement of serum IgG and IgG4, serum thyroid hormones and thyroid autoantibodies. An overall ophthalmic assessment was performed pretherapy (week 0) and post-therapy (week 12).

RESULTS

33.3% of GO patients (23/69) had elevated IgG4 levels. IgG4 levels were positively correlated with the severity and activity of GO. After GC therapy, IgG4, IgG4/IgG, vision and CAS were significantly improved in GO patients. Patients with high IgG4 levels had a significantly reduced extraocular muscle area (EOMs) and better clinical outcomes than patients with normal IgG4 levels.

CONCLUSIONS

Our results suggest a possible subgroup of elevated IgG4 GO patients, with more severe ophthalmopathy and better response to GCs treatment compare with normal IgG4 GO patients.

IgG4 as a Biomarker in Graves' Orbitopathy

Immunoglobulin G4-related disease (IgG4-RD) is a chronic inflammatory disorder associated with fibrosis and abundant tissue lymphoplasmacytic infiltrations. It typically affects the pancreas, the salivary glands, and the retroperitoneal space. However, it might also involve multiple other organs, including the orbit and the thyroid. Recent studies have suggested that IgG4 plays a role in the pathophysiology of autoimmune thyroid diseases. This ultimately led to the establishment of new clinical entities called IgG4-related thyroid disease and thyroid disease with an elevation of IgG4. The aim of this paper is to describe the pathophysiological, histopathological, and clinical features of Graves' Disease (GD) and Graves' Orbitopathy (GO) with elevated IgG4 levels. Multiple studies have demonstrated higher IgG4 serum concentrations in GD patients than in healthy euthyroid controls. Depending on the studied population, elevated serum IgG4 levels occur in 6.4-23% (average: 10.3%) of all patients with GD, 8.3-37.5% (average: 17.6%) of patients with GO, and 0-9.8% (average: 5.4%) of patients with GD without GO, while GO patients comprise 37.5-100% (average: 65.8%) of all GD patients with elevated IgG4 levels. Characteristic features of GD with elevated IgG4 levels include lower echogenicity of the thyroid gland on ultrasound examination, peripheral blood eosinophilia, higher prevalence of orbitopathy, and better response to antithyroid drugs with a tendency to develop hypothyroidism when compared to patients with GD and normal levels of IgG4. Typical signs of GO accompanied by increased concentration of IgG4 include younger age at diagnosis, and more severe course of the disease with a higher Clinical Activity Score (CAS).. We strongly recommend considering the diagnosis of GO with elevated IgG4 in patients with an established diagnosis of GD, elevated serum IgG4 levels, and clinical features of ophthalmic disease overlapping with those of IgG4-related orbital disease.

Elevated Immunoglobulin G4 Levels in Patients with Thyroid Eye Disease and Their Clinical Implications

Purpose

The purpose of this study was to assess the relationship between thyroid eye disease (TED) in patients undergoing orbital decompression and immunoglobulin G4 (IgG4) levels.

Methods

A prospective observational cohort study was conducted among 185 consecutive patients who were diagnosed with TED and underwent orbital decompression. Serum levels of IgG4 were measured, and immunohistochemical staining for IgG and IgG4 was performed in orbital adipose tissue. Data related to clinicopathologic features were analyzed.

Results

Among the 185 enrolled patients with TED, 64 (34.6%) were IgG4-positive. The IgG4-positive patients were older, had higher clinical activity scores (CAS), and had worse best-corrected visual acuity (BCVA) than the IgG4-negative patients. Higher thyrotropin receptor antibody (TRAb) levels, histopathological IgG4 counts, IgG4/IgG ratios, and dense lymphocyte infiltration were more frequently observed in IgG4-positive than in IgG4-negative patients. Definitive and probable IgG4 subtypes were independently associated with the active stage in patients with TED.

Conclusions

Our data suggest that the IgG4 subtype in TED is common. IgG4-positive patients with TED may be older, have more severe disease, and have higher clinical activity scores. IgG4 may play an important role in the pathogenesis of TED.

DIAGNOSIS OF ENDOCRINE DISEASE: IgG4-related thyroid autoimmune disease

IgG4-related disease (IgG4-RD) is fibro-inflammatory, immune-mediated, systemic disease recognized as a defined clinical condition only in 2001. The prevalence of IgG4-RD is 6/100 000, but it is likely to be underestimated due to insufficient awareness of the disease. The diagnostic approach is complex because of the heterogeneity of clinical presentation and because of rather variable diagnostic criteria. Indeed, high concentrations of IgG4 in tissue and serum are not a reliable diagnostic marker. The spectrum of IgG4-RD also includes well-known thyroid diseases including Riedel's thyroiditis, Hashimoto's thyroiditis and its fibrotic variant, Graves' disease and Graves' orbitopathy. Results from clinical studies indicate that a small subset of patients with the above-mentioned thyroid conditions present some features suggestive for IgG4-RD. However, according to more recent views, the use of the term thyroid disease with an elevation of IgG4 rather than IgG4-related thyroid diseases would appear more appropriate. Nevertheless, the occurrence of high IgG4 levels in patients with thyroid disease is relevant due to peculiarities of their clinical course.

A study of serum IgG4 levels in the clinical metamorphosis of autoimmune thyroid disease

Background

Measurement of serum IgG4 had been suggested to distinguish the unique subtypes of autoimmune thyroid disease (AITD) which demonstrated patterns of fluctuating between hyperthyroidism and hypothyroidism. However, the clinical utility of serum IgG4 measurement is inconclusive due to few studies having addressed these unusual patients compared with the specificity of serum IgG4 in healthy patients.

Aim

To investigate whether elevated serum IgG4 levels could be used as a marker to identify fluctuating AITD patients.

Materials and Methods

20 AITD patients who evolved from hyperthyroid Graves’ disease to spontaneous hypothyroidism or vice versa were compared with 40 healthy subjects, 40 patients with hyperthyroid Graves’ disease (GD) and 40 patients with subclinical or overt hypothyroid Hashimoto’s thyroiditis (HT). Serum levels of total IgG and IgG4 were measured and the proportion of elevated serum IgG4 levels (defined by serum IgG4 levels ≥ 135 mg/dL) was compared with control patients.

Results

A series of 20 Thai patients with clinical evolution of AITD was analyzed with a median follow-up at 92 months (range 3–380 months). Elevated serum IgG4 levels were not found in fluctuating AITD patients but were found in 5% of the control GD patients, 2.5% of the control HT, and 2.5% of healthy subjects which were not statistically significant between each group.

Conclusion

Our results contrasted with those of previous studies from Japan which reported elevated serum IgG4 as a marker to identify subset of AITD patients. At present, the clinical utility of serum IgG4 measurements in AITD is inconclusive and requires further investigation.

Clinical Implications of Immunoglobulin G4 to Graves' Ophthalmopathy

BACKGROUND

This study aimed to explore the relation of immunoglobulin G4 (IgG4) to clinical and laboratory characteristics of patients newly diagnosed with Graves' disease (GD) without or with Graves' ophthalmopathy (GO) and to analyze association of IgG4 with development and grade of GO in GD patients.

METHODS

Sixty-four GD patients and 64 sex- and age-matched euthyroid subjects were enrolled. Serum levels of thyroid hormones, thyroid autoantibodies, immunoglobulin G (IgG), and IgG4 were measured, and ophthalmological and ultrasonographical evaluation was performed.

RESULTS

In GD patients compared with euthyroid subjects, levels of thyroid hormones, thyroid autoantibodies and IgG4 as well as the IgG4/IgG ratio were elevated. GD patients having GO in comparison to not having GO were characterized by a female predominance; a high incidence of smoking history; high levels of T3, free T4, TSH receptor autoantibody (TRAb) and IgG4; and a high IgG4/IgG ratio after adjusting for sex. In GD patients, the IgG4 level was the independent factor associated with GO development on multivariate analysis. When severity and activity of GO were classified using the European Group on Graves' Orbitopathy criteria in GD patients with GO, IgG4 levels and IgG4/IgG ratio were elevated in the moderate-to-severe group compared with the mild group and in the active group compared with the inactive group. IgG4 levels and IgG4/IgG ratio became elevated as clinical activity score increased. IgG4 levels were positively correlated with TRAb levels. The high IgG4 group in comparison to the normal IgG4 group had a high incidence of family history of autoimmune thyroid disease, high levels of free T4, TRAb and IgG4, a high IgG4/IgG ratio and extensive hypoechogenicity.

CONCLUSIONS

These results suggest that IgG4 levels are elevated in newly diagnosed GD patients compared with euthyroid subjects and in the presence of GO compared with the absence of GO. Moreover, our findings suggest that IgG4 levels are associated with the development and grade of GO in GD patients.