Endocrine Abstracts

Addison’s disease (AD) has an estimated prevalence of 126–144 per million among Northern European populations. Average age at diagnosis is 39, but AD may be diagnosed from pre-teens to 80 year olds.

AD may occur in isolation or as part of autoimmune polyendocrine syndromes. Previous studies identified significant associations with autoimmune thyroid disease (predominantly hypothyroidism), type 1 diabetes mellitis, vitiligo, vitamin B12 deficiency and coeliac disease.

We examined self-reported rates of associated endocrine and autoimmune conditions among British Autoimmune Addison’s Disease (AAD) patients, all members of the Addison’s Disease Self-Help Group (n=444). Co-conditions were analysed by years since diagnosis, with a range from 50 years post-diagnosis. The average years since diagnosis was 12.2. Cohort sizes for advancing decades post-diagnosis were small, making significance tests problematic. Rates of associated conditions generally increased over time, although smaller cohorts were not consistently progressive.

Thyroid conditions increased steadily among each post-diagnosis cohort, to reach 100% of those diagnosed >50 years ago. Type 1 diabetes peaked at 26% among the 31–40 year cohort. Coeliac disease, vitamin B12 deficiency and vitiligo peaked at 10%, 20% and 30% respectively among those diagnosed 41–49 years ago. Premature ovarian/testicular failure peaked at 20% of those diagnosed >50 years ago. (See chart).

Larger Swedish and German studies found broadly similar proportions of AAD patients with thyroid disease. Both had higher rates of insulin-dependent diabetes; rates of B12 deficiency in Sweden were also significantly higher.

These findings are a reminder that AAD patients require lifelong monitoring for the development of co-conditions. Endocrinologists should assume that AAD patients are likely to develop a thyroid condition at some stage, and that AAD should be managed as potentially an autoimmune polyendocrine syndrome, even when it is diagnosed in isolation.