ESPE Abstracts

Background: The increased prevalence of anti-thyroid peroxidase antibodies (anti-TPO) and autoimmune thyroiditis in children with type 1 diabetes (T1D) has been previously well described. However, the necessity for screening for anti-TPO in children who have not been diagnosed with T1D yet, but have a HLA-conferred susceptibility to T1D, has not been reported. A 3% prevalence of anti-TPO in healthy children has been shown in studies using a cut-off value of >100 kU/L for clinically significant anti-TPO level. The aim of this study was to evaluate the serum levels of anti-TPO and the prevalence of clinically significant anti-TPO positivity in children with HLA-conferred susceptibility to T1D.

Methods: Serum concentrations of anti-TPO in 111 subjects (57 boys) aged 8–9 years with a HLA-conferred susceptibility to T1D were studied. None of them had a known thyroid disease, one of the subjects had already a diagnosis of T1D. The test was performed with ECLIA method. As no universal reference ranges for anti-TPO in children have been agreed upon, we used the test manufacturer’s reference range of < 18 kU/L for this age group. The lower detection limit of the test was 5 kU/l. Clinically significant anti-TPO positivity was set at a concentration of >100 kU/L. The statistical analysis was performed with Excel using the Mann-Whitney test, P<0.05 was considered statistically significant.

Results: Eleven samples of anti-TPO (9.9%) were over the reference range. In 2 cases (1.8%), both girls, anti-TPO was >100 kU/L, suggesting a very likely autoimmune thyroiditis. Those two subjects had normal thyroid function tests. The lowest detected anti-TPO was 7 kU/L, the highest 354 kU/L. Nine out of 11 risen anti-TPO concentrations belonged to girls. Girls had significantly higher median anti-TPO concentration than boys (12.5 vs 10.0 kU/L; P=0.0001).

Conclusion: In children with HLA-conferred susceptibility to T1D the prevalence of clinically significant rise of anti-TPO levels was similar to previously reported data in healthy children. However, almost 10 percent of those children have anti-TPO levels above the reference range. Further studies are necessary to clarify the clinical significance of this finding.