Increasing incidence of childhood thyrotoxicosis in a population-based area of central Sweden

Abstract

Aim: To study the incidence, prevalence and clinical characteristics of childhood thyrotoxicosis in a population-based area comprising five counties in central Sweden.

Methods: Retrospective analysis of the medical records of all children below 16 y of age with thyrotoxicosis during a 10-y study period.

Results: Forty-six children were identified with thyrotoxicosis. The median age at onset was 11.7 y and 85% were females. At the end of the study period on 31 December 1999, the prevalence was 0.08 per 1000. The mean annual incidence was four times higher in the second 5-y period than in the first (2.7 and 0.7 per 100000, respectively; p < 0.001). A first-degree relative with thyrotoxicosis was found in 21% of the children and 11/46 children (24%) showed autoimmune-related co-morbidity. Increased heart rate was observed in 95%, goitre in 67% and exophthalmos in 33% of the children. TSH was completely suppressed and free T4 was clearly above the upper reference limit in all children. TSH receptor-stimulating antibodies and peroxidase antibodies were observed in 80% and 71% of the children, respectively.

Conclusion: This study indicates an increase in the incidence of childhood thyrotoxicosis in a population-based area of central Sweden. A prospective study aimed at identifying specific aetiological risk factors for development of thyrotoxicosis has been initiated.