Subclinical thyrotoxicosis in an outpatient population - predictors of outcome.

OBJECTIVE: Individuals with endogenous subclinical thyrotoxicosis (SCT) may subsequently require treatment for overt disease. We aimed to evaluate the frequency of progression to hyperthyroidism and factors influencing this outcome. DESIGN: This is a retrospective analysis of outcome in 96 consecutive patients (aged 16-91 years) diagnosed with SCT over a 6-year period. Individuals with secondary causes of TSH suppression were excluded. Mean follow-up was 3·8 years. The significance of age, gender, family history of thyrotoxicosis, symptoms at presentation, thyroid nodule(s) on clinical examination, entry TSH level, antithyroid antibody status and (99m) Tc pertechnetate thyroid imaging results on subsequent development of overt thyrotoxicosis was assessed. RESULTS: Progression to overt thyrotoxicosis was seen in 8% at 1 year, 16% at 2 years, 21% at 3 years and 26% at 5 years. Multivariate analysis determined that diagnosis as determined by scintiscan to be the only independent predictor of outcome (P = 0·003) with the cumulative percentage requiring therapy at 5 years being 9% for subclinical Graves' disease, 21% for multinodular goitre and 61% for the autonomous nodule subgroup. CONCLUSIONS: Progression of SCT to overt hyperthyroidism occurred at a rate of 5-8% per year with disease aetiology, as determined by thyroid scintigraphy, significantly influencing risk of progression.

Juvenile thyrotoxicosis--a South Island, New Zealand experience with long-term outcome.

AIM: To assess our experience in the management of juvenile thyrotoxicosis. METHOD: Retrospective review of thyroid clinic records of juvenile (<16 y) thyrotoxic (JT) patients treated at thyroid clinic between 1972 and 1999. Long-term (>8 y) treatment outcome was assessed. RESULTS: During the 28-year period, 34 JT patients were diagnosed and treated--30 girls and 4 boys, median age 13 years (5.6-15.9 y). Thirty-two children had Graves' disease and two had toxic nodular goitre. All patients were initially treated with carbimazole, and no major adverse reactions occurred. One Graves' disease child later developed severe ophthalmopathy. During long-term follow-up, 12 of the 32 Graves' patients remain in remission after antithyroid drug treatment alone, but 4 of these 12 patients are currently receiving thyroxine replacement. Fifteen patients were surgically treated (median age 16 y), and six patients received radioiodine therapy (median age 18 y) including one patient with post-thyroidectomy relapse. The two patients with toxic nodular goitre were treated by thyroidectomy. CONCLUSION: Juvenile thyrotoxicosis is relatively rare and not always due to Graves' disease. More than a third of children with Graves' disease achieved long-term remission following antithyroid drug therapy, and remaining patients required definitive therapy.