Introduction: Autoimmune thyroid disease and type 1 diabetes (T1DM) are two autoimmune diseases frequently associated, especially in pediatric population. Aims: we wanted to determine and ilustrate the relationship between type 1 diabetes and autoimmune thyroiditis and also the factors than can influence it, like gender, age, diabetes duration. Glycemic control was also evaluated for all the patients.
Material and methods: There were studied 256 patients, children and adolescents with T1DM (male/ female: 145/115; 55%/45%). Anti-TPO antibodies were detected using the electrohemiluminescence method and glycosylated haemoglobin A1c (HbA1c) was measured through a imunoturbidimetric method. The patients were clinically examined, including thyroid gland palpation, blood pressure measurement and assessment of their pubertal status and growth.
Results: Age distribution at the time of T1DM diagnosis: most of them, 26% were diagnosed between 6 and 9 years, 23% between 1-3 years, 21% between 3-6 years, 19% between 9-12 years, 9% between 12-15 years, and very few of them (2%) were diagnosed between 15 and 18 years. Among these patients, 47/256 (18.3 %) were positive for thyroid antibodies (anti - TPO). In 2 of 47 patients tests for anti TPO antibodies were positive at the time of T1DM diagnosis. Tests for anti - TPO antibodies became positive with an average of 5.09±3.84 ( range 0-13) years after the diagnosis of T1DM. At the time that anti - thyroid antibodies were first seen to be positive all patients were euthyroid with a mean age of 11.3 years (range 4 -16) and a mean diabetes duration of 5.21±3.57 (range 0-9 years). After 5±3.3 years (range 0- 9 years) a progression towards subclinical hypothyroidism due to Hashimoto thyroiditis was observed in 41 from 47 patients (87.2%), while no patient developed clinical hypoythyroidism. It was observed an 9.2 % ±1.5% mean value of HbA1c in patients with thyroiditis comparative with 7.9 % ± 0.7 % mean HbA1c value in those without thyroiditis.
Conclusions: Thyroid autoimmunity is frequently present among T1DM patients, can be associated with increased age, female gender, long diabetes duration, and can inbalance the glycemic control of T1DM patients.