Iodine supply and prevalence of thyroid autoimmunity and autoimmune thyroiditis in children and adolescents between 1 and 16 years old in our city

E. Garcia-Garcia; M. Vazquez-Lopez; E. Garcia-Fuentes; F. Rodriguez-Sanchez; J. Munoz-Vico; A. Bonillo; F. Soriguer

Introduction: Thyroid autoimmunity is related to iodine supply. Iodine nutrition has improved in our country, but the prevalence of autoimmune thyroiditis in our children is unknown.

Objectives: To determine the status of iodine nutrition in children and adolescents in our city. To calculate local prevalence of thyroid autoimmunity and autoimmune thyroiditis in pediatric ages.

Design: Cross-sectional epidemiological study.

Subjects and methods: By a multistage probability sampling 1387 children and adolescents aged between 1 and 16 were selected. Physical examination was carried out including neck palpation. Parents were asked about eating habits, social and demographic aspects. Urinary iodine, free thyroxine, TSH and antiperoxidise and antityroglobulin antibodies were measured. Thyroid autoimmunity was diagnosed when any antibody was positive and autoimmune thyroiditis when autoimmunity was associated with impaired thyroid function or goitre. To study the relation between thyroid autoimmunity and urinary iodine with independent variables we used binary and multiple logistic regression and multiple lineal regression.

Results: Median urinary iodine was 199.5 μg/l. The prevalence of thyroid autoimmunity and autoimmune thyroiditis were 3.7% (2.4–5.0) and 1.4% (0.4–2.4). Thyroid autoimmunity is associated with female sex (OR 2.78; P<0.001) and age (OR 1.30; P<0.001). Iodine status is associated with milk and dairy products (P<0.001) and vegetable intake (P=0.021), but not with use of iodated salt at home (P=0.1).

Conclusions: The iodine supply in children and adolescents in our city is optimal. Milk and dairy products are the most important iodine source. Thyroid autoimmunity and autoimmune thyroiditis are prevalent in pediatric ages in our city mainly in females and older subjects.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.

**Table 1**
	Thyroid autoimmunity	Autoimmune thyroiditis
	Prevalence (% and confidence interval at 95%)	Prevalence (% and confidence interval at 95%)
Total group	3.7 (2.4–5.0)	1.4 (0.4–2.4)
Males	2.3 (1.1–3.5)	0.8 (0.0–2.8)
Females	5.0 (3.4–6.6)	1.9 (0.9–2.9)
Prepubertal	2.4 (1.2–3.6)	0.5 (0.0–1.8)
Pubertal	6.8 (4.2–9.4)	3.0 (1.4–4.6)
12–16 years old	6.2 (4.9–7.5)	3.2 (0.0–6.5)
6–12 years old	4.6 (2.6–6.6)	1.2 (0.0–2.4)
1–6 years old	0.6 (0.0–2.6)	0.0 (0.0–0.9)

Endocrine Abstracts

P1670