BONE MASS IN CHILDREN WITH CONGENITAL HYPOTHYROIDISM TREATED WITH THYROXINE SINCE BIRTH

To determine whether the large doses of thyroxine treatment early in l ife adversely affect bone mass, we measured bone mass of 20 congenital hypothyroid (CH) patients (8.4 +/- 2.2 years) who were diagnosed and treated since birth, Starting thyroxine dose and current dose were 8.5 +/- 1.9 mu g/kg/day and 3.1 + 1.2 mu g/kg/day respectively, Thyroid f unction and serum biochemical tests for calcium homeostasis were norma l at the time of study, Bone mass was measured by dual energy X-ray ab sorptiometry, Nine siblings served as controls, The patients' bone min eral density was within the normal range of population controls, and w as not different from the sibling controls, The patients also had heig ht-adjusted bone mineral content equal to the expected height-adjusted values in the siblings, Our studies indicate that the large doses of thyroxine therapy for CH do not cause osteopenia in childhood.