AUTOIMMUNE HYPERTHYROIDISM IN PREPUBERTAL CHILDREN AND ADOLESCENTS - COMPARISON OF CLINICAL AND BIOCHEMICAL FEATURES AT DIAGNOSIS AND RESPONSES TO MEDICAL THERAPY

We explored our clinical impression that young children with autoimmun e hyperthyroidism are more thyrotoxic at presentation and require a lo nger course of medical therapy than do adolescents to achieve remissio n. A retrospective chart review of clinical and biochemical data at pr esentation and response to therapy in 32 prepubertal (PREPUB) and 68 p ubertal (PUB) children and adolescents with autoimmune hyperthyroidism was undertaken. Initial therapy included prophylthiouracil or methima zole in all but 11 patients who chose radioactive iodine (I-131); 30 a dditional patients ultimately chose I-131 or surgery after an initial period of medical therapy. In PREPUB children there were significantly longer duration of symptoms (7.8 +/- 7.7 months) and higher serum con centrations of triiodothyronine (T-3) 708 +/- 330 ng/dL) at presentati on than in the PUB group (4.7 +/- 3.4 months; p < .05) (537 +/- 197 ng /dL; p < .01). Duration of symptoms correlated negatively with chronol ogic age (r = -0.24; p < .02) but not with T-3 or thyroxine (T-4) leve ls (p = .1). PUB children had significantly higher titers of thyroid m icrosomal antibodies (positive dilution factor 1:6022 +/- 14572) than did PREPUB children (1:592 +/- 1226; p < .05). There was a higher fami lial incidence of thyroid disease in boys (80%) than in girls (64%) (p < .02). The duration of medical therapy was significantly longer (3.5 +/- 2.9 years) in PREPUB children compared to the PUB group (2.2 +/- 1.8 years) (p < .05). Only 17% of PREPUB treated 5.9 +/- 2.8 years com pared with 30% of PUB treated 2.8 +/- 1.1 years achieved a 1-year remi ssion after stopping antithyroid medication (percentage between groups , p < .01; years of treatment, p < .05). The median time to remission after medical therapy was 8 years in PREPUB and 4 years in PUB (p < .0 2). PREPUB children continued to remit after prolonged medical therapy (>6 years) whereas PUB patients did not. Total treatment length corre lated negatively with chronological age (r = -0.26; p < .05) and posit ively with T-4 and T-3 concentrations at diagnosis (r = 0.31; p < .01) . The diagnosis of hyperthyroidism is delayed in prepubertal children compared to adolescents. This delay may contribute to the higher T-3 l evels observed in this group at presentation. Prepubertal children als o appear to require longer medical therapy to achieve a lower rate of remission, but do continue to remit after prolonged treatment. These d ifferences in response to therapy should be considered when discussing therapeutic options with the family.