Intensive therapy needed in paediatric triiodothyronine-predominant Graves' disease

By Eleanor McDermid, Senior medwireNews Reporter

Paediatric patients with triiodothyronine (T3)-predominant Graves' disease (GD) develop severe disease that needs increased doses of antithyroid drugs (ATD), a study shows.

Julie Harvengt (Hôpital Robert Debré, Paris, France) and colleagues found that children with this form of GD required sustained treatment with double the dose needed in patients with classical GD.

“These findings highlight the need to measure serum free [f]T3 levels and to evaluate fT4/fT3 ratio in patients with GD, particularly those displaying persistent hyperthyroid symptoms with suppressed serum TSH [thyroid-stimulating hormone] levels but serum fT4 levels within the normal range”, writes the team in the European Journal of Endocrinology.

Eight (13%) of 60 children treated for GD over a 10-year period in a single centre developed T3-predominant GD, defined as having fT3 levels greater than 8.0 pmol/L with normal fT4 levels and undetectable TSH.

The patients were diagnosed a median of 10.5 months after their initial GD diagnosis, with four diagnosed a few months after the initial diagnosis and four following relapse after stopping ATD therapy.

At baseline, patients who developed T3-predominant GD had significantly higher levels of TSH receptor autoantibodies than those with classical GD, and all had medium or larger goitres, whereas 21% of those with classical GD had small or no goitres.

All patients were treated with carbimazole, at an initial median dose of 0.77 mg/kg per day, which was similar to the dose given to the children with classical GD. During treatment of up to 36 months, the median dose needed to control thyroid hormone levels fell in the children with classical GD, but remained high in the patients with T3-predominant GD, who required about double the dose for most of the treatment period.

Although long-term ATD treatment in children has received little study, the team suggests that “a good approach might be to treat these patients with ATD until they become euthyroid, thereby decreasing the risk of cardiovascular, growth and skeletal complications.”

They add: “Careful discussion with the parents and the child is then required, to determine the best choice of treatment between long-term ATD and more definitive options, such as radioiodine treatment and thyroidectomy, as large prospective randomized trials with long-term quality-of-life assessment have not yet been carried out to address this issue in children.”

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