Introduction
Hyperthyroidism is less frequent in children than adults, and its clinical profile is different, the aim of our study was to analyze the clinical characteristics of hyperthyroidism in children and adolescents.

Material and Methods
It is a retrospective study concerning all patients aged twenty years or less presenting for hyperthyroidism during a period of thirty one years [1981-2012]. Their medical records were reviewed. We analyzed sex ratio, age at diagnosis, presenting symptoms, etiologies, complications and treatment modalities.

Results
161 patients were recruited. Sex ratio was of 4 Females/1 Male, mean age at diagnosis was 15.63 ± 3.51 years. Age clusters at diagnosis was as follows, less than 10 years in 6.9%, between 10 and 16 years in 48.8%, between 16 and 20 years in 44.3%. Diagnosis delay was of 20.73 ± 20.69 months. Etiologies were as follows, Graves’ disease in 98.13%, nodular goiter in 1.24% and thyroïditis in 0.63%. Appealing symptoms were thyrotoxicosis symptoms in 69%, goiter in 16% and ophtalmological signs in 15%. Clinical presentation was obvious in 81% and discrete in 19%. Goiter was of type II/type III in 74% and of type I in 26%. Exophtalmous was present in 69% and was severe in 12.5%. Complications were as follows, cardiothyreosis (heart failure) in 1.86%, dysglycemia in 13.04% (diabetes in 4.34% and prediabetes in 8.70%), myopathy in 3.72% and behavioral disorders in 6.83%. Treatment was medical using antithyroid drugs in 68.94%, surgery in 26.1%, radioiodine treatment in 3.1% and surgery plus radioiodine treatment in 1.86%.

Discussion
Thyrotoxicosis is rare in children with a frequency of 0.1-3/100 000 person-years (Lavard, 1994). The majority of patients are diagnosed during puberty as was in our study where the mean age at diagnosis was 15.63 ± 3.51 years. As in adults, hyperthyroidism predominates in females. Diagnosis is often delayed (Shulman, 1997), in our study, diagnosis delay was of 20.73 ± 20.69 months. Prepubertal children present for weight loss or frequent stools whereas pubertal children present for classical signs of thyrotoxicosis as heat intolerance, irritability, palpitations or for goiter (Lazar, 2000). As for Lazar (2000) all our patients had palpable goiters, it was small in 26% and medium to large in 74%. Graves’ disease is the cause of around 95% of hyperthyroidism in children (Birrell, 2002). Ophtalmopathy is reported in 25-63% (Chan, 2002), it was observed in 69% of our patients. The delayed diagnosis reported earlier may account for the severity of hyperthyroidism in children as complications were observed in almost one fourth of our patients. Remission of Graves’ disease is rare in children occurring in less than one third of patients after several years of medical treatment (Bauer, 2011), so many patients may require definitive treatment either surgery or radioiodine treatment.

Conclusion
Hyperthyroidism is rare in children and adolescents as only 161 cases were recruited during thirty one years. Although clinical presentation is obvious, diagnosis is often delayed, which may explain the possible occurrence of complications even in young patients. Graves’ disease is the main etiology. Relapsing of Graves’ disease is frequent in children after antithyroid drug withdrawal, so many patients require definitive treatment.

References
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