Thyroid autoimmunity in schoolchildren in an area with long-standing
iodine sufficiency: Correlation with gender, pubertal stage, and
maternal thyroid autoimmunity
Background: A strong genetic background and gender are believed to be
involved in thyroid autoimmunity (TA). The age these factors become
manifest is less clear, however. The objective of the present study was
to determine the prevalence of TA in children and adolescents and to
determine if there are relationships between the period of onset of TA
and gender and between TA and maternal autoimmunity.
Methods: Antithyroperoxidase antibodies (anti-TPO Ab), antithyroglobulin
antibodies (anti-Tg Ab), thyrotropin, thyroxine, triiodothyronine, and
urinary iodine were determined in 440 healthy schoolchildren (200 boys
and 240 girls), aged 5-18 years, and in 123 mothers living in an
iodine-replete region.
Results: The prevalence of positive anti-TPO and anti-Tg Ab was 4.6%
and 4.3%, respectively. In girls, the prevalence of positive anti-TPO
Ab was higher in Tanner stage II-V compared to Tanner stage I (8.2% vs.
2.2%; p < 0.05). No difference was detected with regard to anti-Tg Ab.
In girls, positive anti-TPO and anti-Tg Ab levels were associated with
significantly greater thyroid volume. Hypoechogenicity was detected in
52.6% and 36.8% of the children with positive anti-TPO or anti-Tg Ab,
respectively (p = 0.0005). The prevalence of autoimmune thyroiditis, as
defined by positive serum anti-TPO and/or anti-Tg and an echographic
pattern of the thyroid gland having diffuse or irregular
hypoechogenicity, was 2.5%. Mothers of anti-TPO Ab positive children
had positive anti-TPO Ab more frequently compared to mothers of anti-TPO
Ab negative children (82% vs. 18%; p = 0.0005). Mothers of anti-Tg Ab
positive children had positive anti-Tg Ab more frequently compared to
mothers of anti-Tg Ab negative children (75% vs. 25%; p = 0.0005).
Conclusions: These findings demonstrate that thyroid antibody positivity
in children was significantly associated with maternal autoimmunity and
their development in girls emerges at puberty. Since heredity, female
gender, and puberty are strongly associated with TA, girls in families
with TA should be examined at the onset of puberty
