Graves' disease in children with Down syndrome.

While subclinical or overt hypothyroidism are common in Down syndrome (DS); Graves´ disease (GD) is rare (ranges 0.6%-3%). We aimed to evaluate the clinical features, course, and treatment of GD in children with DS and compare them with those without DS. Among 161 children with GD, 13 (8 f, 5 m) had DS (8%). Data were collected retrospectively from patients' medical records. The mean age at diagnosis was 10.6 ± 4.5 yrs., with a female-to-male ratio 1.6:1. The main symptoms were weight loss (n=6), increased irritability (n=3), and increased sweating (n=3). None had orbitopathy. Seven of 11 patients with a thyroid ultrasound at diagnosis had a goitre. On admission, all had TSH <0.01 mU/L (normal range (NR): 0.51-4.30), fT3, fT4 (mean±SD), and TRABs (median, range) were 22.2 ± 10.2 pmol/L (NR: 3.5-8.1), 50.2 ± 18.7 pmol/L (NR 12.6-20.9), and 17.0 (2.89-159.0) U/L (NR <1), respectively. Patients were treated either with methimazole (n=10) or carbimazole (n=3), a dose of 0.54 ± 0.36 mg/kg/day. The treatment was "block and replace" in 10 patients and "dose titration" in three patients, with a mean duration of 43.4±11.0 months. Of 13 patients, four are still receiving primary treatment, three are in remission, one patient had two medically treated recurrences, three underwent surgery without complications, and two patients were lost to follow-up. Our data show that the clinical course of GD in patients with DS was similar to those without DS and suggest that a prolonged medical therapy should be the preferred option.