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

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.

Reference
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.