Thyroid Eye Disease

IgG4 serum concentration may be a marker of thyroid eye disease activity

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The clinical profile of patients with thyroid eye disease (TED) with high IgG4 and with normal IgG4 are different, leading researchers to believe this may be a marker of disease activity.

More data is needed, according to the researchers, to determine if the marker potentially represents a distinct clinical entity related to IgG4-related disease.

In this prospective observational study, 60 adults with TED underwent IgG4 serum concentration measurement. High IgG4 GO was defined as an IgG4 concentration exceeding 135 mg/dl. TED activity levels were assessed with clinical activity score (CAS) and magnetic resonance imaging (MRI).

Of the 25% of patients with elevated IgG4 levels, all had a higher prevalence of active GO by MRI than patients with normal IgG4 (64.44%). Higher eosinophile count in peripheral blood, a lower bilirubin level, a more frequent lower eyelid retraction, and a lower prevalence of glaucoma were also noted in these patients.

No statistically significant differences in CAS were found between the groups.

The receiver operating characteristic (ROC) analysis for IgG4 as a marker of active TED had 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%

“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,” the authors concluded.

Olejarz M, Szczepanek-Parulska E, Ostałowska-Klockiewicz A, et al. High IgG4 serum concentration is associated with active Graves orbitopathy. Front Endocrinol (Lausanne). 2023;14:1083321. doi: 10.3389/fendo.2023.1083321. PMID: 36936165; PMCID: PMC10014914.