Influences of Age, Gender, Smoking, and Family History on Autoimmune Thyroid Disease Phenotype

Context: Both genetic and environmental factors contribute to susceptibility to Graves’ disease (GD) and Hashimoto’s thyroiditis (HT), as well as disease manifestations. Objective: The objective of the study was to define how endogenous/environmental factors contribute to variation in phenotype. Design/Setting: This was a multicenter cohort study. Patients/Outcome Measures: We prospectively collected clinical/biochemical data as part of the protocol for a United Kingdom DNA collection for GD and HT. We investigated, in 2805 Caucasian subjects, whether age at diagnosis, gender, family history (FH), smoking history, and presence of goiter influenced disease manifestations. Results: For 2405 subjects with GD, the presence of goiter was independently associated with disease severity (serum free T4 at diagnosis) (P < 0.001). Free T4 (P < 0.05) and current smoking (P < 0.001) were both independent predictors of the presence of ophthalmopathy. Approximately half of those with GD (47.4% of females, 40.0% of males...