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Background: The iodine supply of the population in Berlin has normalized during the last 5 years. Therefore autoimmune thyroiditis has become the most important differential diagnosis in children and adolescents with goiter. Objective: The aim of the present study was to define the prevalence of anti-thyroid peroxidase (TPO) antibodies and autoimmune thyroiditis in children and adolescents with a normalized iodine intake. Design: To enable the measurement of antibodies to thyroid peroxidase (anti-TPO-Ab) in a large cohort, a method to determine anti-TPO-Ab in dried filter paper blood spots was established. In co-operation with pediatricians the antibody prevalence was assessed and data regarding thyroid size, echostructure and the medical history concerning iodine intake and familial thyroid diseases were collected. Methods: 660 children and adolescents participated in the study; urinary iodine, TSH and TPO-Ab were measured and an ultrasound of the thyroid gland was performed. Results: The sensitivity of the newly established filter paper assay was 91.8% and specificity was 100%. The results confirmed the improved iodine supply, with a median urinary iodine concentration of 139 mg iodine/g creatinine. The prevalence of anti-TPO-Ab was 3.4% with a female to male ratio of 2.7:1. Conclusion: The prevalence of anti-TPO-Ab is lower or equal to data reported from other iodine sufficient areas. Data from a moderate iodine deficiency in schoolchildren range from 0.0 to 7.3%. Using the new filter paper method field studies can be implemented to monitor the effect of changes in iodine nutrition on thyroid autoimmunity. Furthermore, this study on the prevalence of anti-TPO-Ab in a cohort of healthy children and adolescents in an iodine replete area can serve as reference data for future investigations and for the comparison with other groups of patients with increased risks for thyroid autoimmunity.

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Constitutively activating thyrotropin-receptor (TSHR) germline mutations have been identified as a molecular cause of hereditary nonautoimmune hyperthyroidism. To date, seven cases of familial and six cases of sporadic nonautoimmune hyperthyroidism have been described associated with 13 different TSHR germline mutations, with a variable clinical course. We report the case of a 12.3-year-old girl with a history of thyrotoxicosis since the age of 11 months who developed diffuse thyroid hyperplasia at the age of 4.5 years. The patient has required continuous moderate-dose antithyroid medication, to maintain euthyroidism. There were no clinical signs of autoimmune thyroid disease and autoantibodies were negative. An activating germline mutation in the TSHR gene was suspected and was found in TSHR exon 10 (Ser505Asn) but was absent in the girl's mother. This same mutation, was first reported in a patient with severe intrauterine hyperthyroidism with early and progressive goiter development. Our patient had a significantly less severe clinical course with later onset compared to the original patient with the same TSHR germline mutation.

SUMMARY To study the effect of thyrotoxicosis on growth, 46 children and adolescents presenting with thyrotoxicosis have been reviewed and followed up for several years, in most cases until adult height was achieved. At presentation the children were underweight for height but were above expected heights even if already well advanced in puberty. Despite bone ages often being very advanced at diagnosis, the condition had no adverse effect on ultimate stature, which was commonly greater than that expected on the basis of parental height. Weight was rapidly regained on treatment, but nevertheless the younger subjects continued to be underweight despite adequate prolonged control of thyrotoxicosis.For many years it has been well recognised that thyroid hormones have a great influence on growth and bone maturation. Most of the evidence about this has been accrued, however, from observations on hypothyroidism.' Overtreatment with thyroid hormones in hypothyroidism results in an excessive acceleration of bone maturation, and thyrotoxicosis in infants has been reported to cause premature closure of skull sutures.2 3 There are, however, few reports of the effect of hyperthyroidism on final height.f6 The reason for this lack of information is that thyrotoxicosis is a rare condition in childhood and most cases develop shortly before or during puberty, when the normal acceleration of growth will be superimposed on any effects of the disease and will make interpretation difficult. A recent monograph on hyperthyroidism gives no special consideration to the condition in childhood or adolescence.7