Celiac.com 02/10/2010 - A team of researchers recently set out to determine whether patients with autoimmune thyroid disease risk developing secondary autoimmune disorders, and whether such diseases tend to cluster in families.

The research team included Kristien Boelaert, PhD, Paul R. Newbya, Matthew J. Simmonds, PhD, Roger L. Holderb, Jacqueline D. Carr-Smitha, Joanne M. Heward, PhD, Nilusha Manjia, Amit Allahabadia, MD, Mary Armitage, DM, Krishna V. Chatterjee, PhD, John H. Lazarus, MD, Simon H. Pearce, PhD, Bijay Vaidya, PhD, Stephen C. Gough, PhD, Jayne A. Franklyn, PhD.

To properly assess the prevalence of coexisting autoimmune disorders, the team conducted a cross-sectional multi-center study of 3286 Caucasian patients at UK hospital thyroid clinics. 2791 of the patients had Graves' disease, while 495 had Hashimoto's thyroiditis.

Patients completed a comprehensive questionnaire detailing personal and parental history of common autoimmune disorders, along with a history of hyperthyroidism or hypothyroidism among parents.

The frequency of developing another autoimmune disorder was 9.67% in Graves' disease and 14.3% in Hashimoto's thyroiditis index cases (P=.005). Rheumatoid arthritis was the most common coexisting autoimmune disorder, striking 3.15% of those with Graves' disease and 4.24% of those with Hashimoto's thyroiditis.

Relative risks of almost all other autoimmune diseases in Graves' disease or Hashimoto's thyroiditis were significantly increased (>10 for pernicious anemia, systemic lupus erythematosus, Addison's disease, celiac disease, and vitiligo).

Results showed relative “clustering” of Graves' disease, and of Hashimoto's thyroiditis, among patients whose parents had hyperthyroidism. Moreover, most other coexisting autoimmune disorders showed markedly increased relative risks for patients with parental history of such disorders.

This effort to quantify the risk of diagnosis of coexisting autoimmune diseases in more than 3000 index cases with well-characterized Graves' disease or Hashimoto's thyroiditis represents one of the most comprehensive studies yet completed.

The elevated risks for developing multiple conditions emphasizes the importance of screening for other autoimmune diagnoses in subjects with autoimmune thyroid disease who present new or nonspecific symptoms.

Source: American Journal of Medicine - Volume 123, Issue 2, Pages 183.e1-183.e9 - February 2010

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