Epidemiology of Childhood Hyperthyroidism in France: A Nationwide Population-Based Study.

CONTEXT: Hyperthyroidism affects all age groups, but epidemiological data for children are scarce.

OBJECTIVE

To perform a nationwide epidemiological survey of hyperthyroidism in children and adolescents.

DESIGN

A cross-sectional descriptive study.

SETTING

Identification of entries corresponding to reimbursements for antithyroid drugs in the French national insurance database.

PARTICIPANTS

All cases of childhood hyperthyroidism (6 months to 17 years of age) in 2015.

MAIN OUTCOME MEASURES: National incidence rate estimated with a nonlinear Poisson model and spatial distribution of cases.

RESULTS

A total of 670 cases of childhood hyperthyroidism were identified. Twenty patients (3%) had associated autoimmune or genetic disease, with type 1 diabetes and Down syndrome the most frequent. The annual incidence for 2015 was 4.58/100,000 person-years (95% CI 3.00 to 6.99/100,000). Incidence increased with age, in both sexes. This increase accelerated after the age of 8 in girls and 10 in boys and was stronger in girls. About 10% of patients were affected before the age of 5 years (sex ratio 1.43). There was an interaction between age and sex, the effect of being female increasing with age: girls were 3.2 times more likely to be affected than boys in the 10 to 14 years age group and 5.7 times more likely to be affected in the 15 to 17 years age group. No conclusions about spatial pattern emerged.

CONCLUSION

These findings shed light on the incidence of hyperthyroidism and the impact of sex on this incidence during childhood and adolescence. The observed incidence was higher than expected from the results published for earlier studies in Northern European countries.