[Thyroiditis and gluten intolerance: extrapancreatic auto-immune diseases associated with type 1 diabetes]

Abstract

Objectives: This study aimed at evaluating the screening of thyroïditis and coeliac disease, in a population of children and adolescents with type 1 diabetes, and at comparing the appearance of antibodies specific for these 2 diseases as a function of age.

Patients and methods: The study included 370 children and adolescents, 179 girls and 191 boys, aged 13.8 +/- 4.4 yr and with diabetes for 7.1 +/- 3.8 yr. Auto-immune thyroïditis was screened using antimicrosomal and antithyroglobulin auto-antibodies, at a mean rhythm of 3 tests per patient (1 every 2 yr), associated with dosages of TSH and FT4. Coeliac disease was screened using antigliadin (+/- antiendomysium) auto-antibodies, at a mean rhythm of 2 tests per patient, and was confirmed by duodenojejunal biopsy. Antithyroïd auto-antibodies were correlated with age following the "censured data analysis" type approach.

Results: Antithyroïd autoantibodies were found in 42 patients (11.4%), of whom 9 were treated for hypothyroïdism and 1 for Basedow disease, and coeliac disease autoantibodies were found in 9 patients (3.2% of tested patients). The cumulated frequency of antithyroïd auto-antibodies increased regularly with age and was significantly higher in girls, reaching 28% in girls and 12% in boys around 18 yr of age. As a consequence of this evolution, antithyroïd auto-antibodies were frequently found at the time of diagnosis of diabetes when it declared after 10 yr of age, while they often became positive secondarily when diabetes occurred before 10 yr of age. Coeliac disease specific auto-antibodies appeared much earlier and were found at the time of diagnosis of diabetes or at the first screening test.

Conclusion: Antithyroïd autoantibodies are increasingly frequent with age in children with type 1 diabetes, and become very elevated in girls. The rhythm for screening should be adapted to this evolution of autoantibodies with age, which is very different between thyroïditis and coeliac disease.