Thyroid Autoimmunity in Children and Adolescents With Type 1 Diabetes

Abstract

OBJECTIVE—To investigate thyroid autoimmunity in a very large nationwide cohort of children and adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS—Data were analyzed from 17,749 patients with type 1 diabetes aged 0.1–20 years who were treated in 118 pediatric diabetes centers in Germany and Austria. Antibodies to thyroglobulin (anti-TG) and thyroperoxidase (anti-TPO) were measured and documented at least once in 7,097 patients. A total of 49.5% of these patients were boys, the mean age was 12.4 years (range 0.3–20.0 years), and the mean duration of diabetes was 4.5 years (range 0.0–19.5 years). A titer exceeding 100 units/ml or 1:100 was considered significantly elevated. RESULTS—In 1,530 patients, thyroid antibody levels were elevated on at least one occasion, whereas 5,567 were antibody-negative during the observation period. Patients with thyroid antibodies were significantly older (P < 0.001), had a longer duration of diabetes (P < 0.001), and developed diabetes later in life (P < 0.001) than those without antibodies. A total of 63% of patients with positive antibodies were girls, compared with 45% of patients without antibodies (P < 0.001). The prevalence of significant thyroid antibody titers increased with increasing age; the highest prevalence was in the 15- to 20-year age group (anti-TPO: 16.9%, P < 0.001; anti-TG: 12.8%, P < 0.001). Thyroid-stimulating hormone (TSH) levels were higher in patients with thyroid autoimmunity (3.34 μU/ml, range 0.0–615.0 μU/ml) than in control subjects (1.84 μU/ml, range 0.0–149.0 μU/ml) (P < 0.001). Even higher TSH levels were observed in patients with both anti-TPO and anti-TG (4.55 μU/ml, range 0.0–197.0 μU/ml). CONCLUSIONS—Thyroid autoimmunity seems to be particularly common in girls with diabetes during the second decade of life and may be associated with elevated TSH levels, indicating subclinical hypothyroidism.