GENDER INFLUENCES THE CLINICAL PRESENTATION AND LONG-TERM OUTCOME OF GRAVES DISEASE.

OBJECTIVE: The outcome of antithyroid drug (ATD) treatment for Graves disease (GD) is difficult to predict. In this study, we investigated whether male gender, besides other factors usually associated with a poor outcome of ATD treatment, may affect disease presentation and predict the response to medical treatment in subjects with GD.

METHODS: We studied 294 patients with a first diagnosis of GD. In all patients, ATD treatment was started. Clinical features, thyroid volume, and eye involvement were recorded at baseline. Serum levels of free thyroxine (FT4), free triiodothyronine (FT3), thyroid-stimulating hormone (TSH), and TSH-receptor antibodies (TRAb) were measured at baseline and during the follow-up. Treatment outcome (FT4, FT3, and TSH serum levels and further treatments for GD after ATD withdrawal) was evaluated.

RESULTS: When compared to women, men showed a significantly larger thyroid volume and a higher family positivity for autoimmune diseases. During ATD, the mean serum levels of TSH, FT4, FT3, and TRAb did not differ between groups. Within 1 year after ATD discontinuation, relapse of hyperthyroidism was significantly more frequent in men than in women. Within the 5-year follow-up period, the prevalence of men suffering a late relapse was higher compared with that of women. The outcome at the end of the 5-year follow-up period was significantly associated with gender and TRAb levels at disease onset.

CONCLUSION: Male patients with GD have a poorer prognosis when submitted to medical treatment with ATDs. A larger goiter at presentation and a stronger genetic autoimmune background might explain this gender difference in patients with GD.

ABBREVIATIONS: ATD = antithyroid drug FT3 = free triiodothyronine FT4 = free thyroxine GD = Graves disease GO = Graves orbitopathy RAI = radioiodine TRAb = thyroid-stimulating hormone-receptor antibody TSH = thyroid-stimulating hormone.