Serum I mmunoglobulin G 4 levels are elevated in patients with G raves’ ophthalmopathy

Summary Objective Recent studies have shown close association between serum I mmunoglobulin G 4 ( I g G 4) levels and forms of autoimmune thyroiditis. However, there are limited data about the relationship between I g G 4 and G raves’ ophthalmopathy ( GO ). In the present study, we aimed to determine the possible association between I g G 4 and GO . Design Cross‐sectional study. Patients Sixty‐five patients with G raves’ disease ( GD ) and 25 healthy controls were recruited into the study. Thirty‐two of these patients had GO . Measurements Serum I g G 4 levels, thyroid functions and thyroid volumes were measured in all participants. Ophthalmological examination including H ertel's exophthalmometer readings ( HER ), Schirmer's test ( ST ), ‘ NO SPECS ’ classification and clinical activity score evaluation ( CAS ) were performed to all patients with GD . Results I g G 4 levels were significantly elevated in patients with G raves’ disease compared to controls ( P  =   0·0001). Also, I g G 4 levels were significantly higher in patients with and without GO when compared to control subjects ( P  =   0·0001 and P  =   0·002, respectively). Furthermore, I g G 4 levels were significantly higher in the GO group compared with GD patients without GO ( P  =   0·024). I g G 4 levels were observed to increase in parallel to CAS . Compared with other GD patients, 15 GD patients with serum I g G 4 levels ≥135 mg/dl had higher CAS scores ( P  =   0·012). None of the factors including, TSH , T 3, T 4 levels, thyroid volume, HER and ST measurements, affect I g G 4 levels as an independent factor. Conclusion I g G 4 levels are evidently increased in patients with GD , and there is a possible relationship between I g G 4 and GO . Our results suggest that I g G 4 may be helpful in screening GD patients with high risk for GO and may well become a good indicator for the selection of right medication in the future.