Endocrine Abstracts

Purpose: Recent reports strongly suggest that at least some cases of Hashimoto’s thyroiditis (HT) may be closely associated with IgG4-related disease. In the present study we aimed to find out, whether the measurement of serum IgG4 allows for an identification of distinct types of HT, with different clinical, sonographic and serologic characteristics.

Methods: The group studied consisted of 53 patients with HT and 28 healthy individuals. All the participants underwent thyroid ultrasonography and body composition analysis. Serum concentrations of IgG4, TSH, anti-peroxidase antibodies (TPOAb), anti-TSH receptor antibodies, TNFα, TGF-β1, Fas ligand, TRAIL, and chemokines: CXCL9, CXCL11, and CXCL10 were also measured by commercial ELISA or RIA.

Results: The group with IgG4 level >135 IU/ml accounted for 32.5% of the patients. The percentage of male patients was 7.5% in the subgroup with normal IgG4 and 18.2% in the subgroup with high IgG4 concentration. The signs of fibrosis were present in 27.0% of the high-IgG4 patients and in 9.1% of the normal-IgG4 group. The patients with elevated IgG4 required higher doses of L-thyroxine, had significantly lower level of TPOAb (P=0.02) than the non-IgG4-HT individuals, and higher TNFα level in comparison with the controls (P=0.01); whereas the concentrations of other cytokines/chemokines and apoptotic markers did not differ between the groups studied.

Conclusions: Our results suggest that the measurement of serum IgG4 allows for an early identification of patients more rapidly progressing and destructive form of HT, who require higher doses of L-thyroxine. A relatively low TPOAb level and the absence of co-existing autoimmune diseases may suggest a distinct pathomechanism of this type of thyroiditis.

Disclosure: The study was supported by grant number 123-50-723L from the Medical University of Bialystok, Poland.