Autoimmune thyroid disease, including Grave's disease and Hashimoto's thyroiditis, is known to segregate within families presumably due to genetic factors.1 Additionally, there is evidence that individuals with autoimmune thyroid disease are predisposed to other autoimmune diseases though historically this has not been well quantified.2

In this study, Boelaert and colleagues performed a cross-sectional analysis of a multicentre cohort of patients with autoimmune thyroid disease to determine the prevalence of other autoimmune diseases within this population, as well as parental history of thyroid disorders. The cohort consisted of 3286 Caucasian patients seen in UK hospital thyroid clinics. Of these, 2791 had Grave's disease and the remaining 495 had Hashimoto's thryroiditis. The authors also calculated the RR of other autoimmune diseases in this group by comparing to prevalence estimates for these diseases in the general UK population based on aggregated data from a number of other studies.

The study found that a …