Emma Hitt, PhD

May 15, 2012

May 15, 2012 (Florence, Italy) — About 1 in 6 patients with autoimmune thyroiditis also have a nonendocrine-related autoimmune disorder, the most common of which are atrophic gastritis, vitiligo, and celiac diseases, according to new research.

Marco Centanni, MD, professor of endocrinology at the Sapienza University of Rome in Italy, presented the findings here at Joint 15th International Congress of Endocrinology and 14th European Congress of Endocrinology.

According to Dr. Centanni and colleagues, systematic studies of autoimmune thyroiditis and its association with nonendocrine autoimmune diseases "are scarce and mostly based only on the presence of circulating autoantibodies."

Dr. Centanni told Medscape Medical News that all the association studies have been performed in patients with nonendocrine autoimmune diseases who were then evaluated for thyroid autoimmunity.

"A longitudinal study of patients with autoimmune thyroiditis was needed to determine the prevalence and incidence of other nonendocrine autoimmune diseases in this population," he said.

The study involved a large cohort of consecutive outpatients; 28.2% (n = 1541) were diagnosed with autoimmune thyroiditis. When additional autoimmune disorders were suspected, the patients underwent further screening.

Of the 1541 patients with autoimmune thyroiditis, 250 (16.2%) also had a nonendocrine autoimmune disease. Of these patients, about one quarter had more than 1 autoimmune disease.

The most frequent associated disease was chronic atrophic gastritis (34.8%), followed by nonsegmental vitiligo (22.3%), celiac disease (11.0%), antiphospholipids syndrome, and multiple sclerosis (7.6%).

About 10% of the patients (overall mean age, 39 years) were diagnosed before they reached the age of 30. The most frequent diagnoses were vitiligo (39%) and celiac disease (26%); chronic atrophic gastritis was not as common (13%).

Patients with both types of autoimmune disorders were more likely to have thyroxine malabsorption (31% vs 12.3%; odds ratio [OR], 3.60; < .0001), chronic unexplained anemia (2.2% vs 18.3%; OR 8.23; < .0001), and recurrent pregnancy loss (6.9% vs 1.7%; OR, 4.06; < .0001) than patients with only autoimmune thyroiditis.

"The presence of thyroxine malabsorption, chronic unexplained anemia, and recurrent pregnancy loss in patients with autoimmune thyroiditis should induce [the clinician] to look for other autoimmune diseases," Dr. Centanni said.

Which "root fraction of the pathogenesis is common to all autoimmune diseases and which confers specificity" is not known. He noted that it will be important to determine what "causes 1 patient to develop another autoimmune disease, while the remaining 5 of 6 patients have autoimmune thyroiditis only as an isolated disorder."

Asked to comment on the study, Terry F. Davies, MD, from the Mount Sinai School of Medicine in New York City, said it is well known that other autoimmune diseases occur in patients with Hashimoto's thyroiditis, and all clinicians should already be aware of this. "The findings from this presentation emphasize how common this can be," Dr. Davies told Medscape Medical News.

Although there have been many studies with similar findings, these results should remind clinicians to search for other disease in such patients, Dr. Davies noted. "There is a strong genetic component to these diseases, which often occur within families," he added. "Autoimmune diseases have a number of shared genetic susceptibility genes."

The study was not commercially funded. Dr. Centanni and Dr. Davies have disclosed no relevant financial relationships.

Joint 15th International Congress of Endocrinology (ICE) and 14th European Congress of Endocrinology (ECE): Abstract OC2.6. Presented May 7, 2012.

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