Reduced bone mineral density at diagnosis and bone mineral recovery during treatment in children with Graves’ disease

Abstract

Objectives: In children with Graves’ disease, the prevalence of osteopenia is unknown, and the possible restoration of bone mass by antithyroid treatment has not been evaluated. The aim of this study was to prospectively evaluate the bone mineral density (BMD) and bone metabolism at diagnosis and after 1 and 2 years of medical treatment. Twenty-six children (19 girls and 7 boys) aged 11 ± 3.4 years (range 3.4 to 15.3 years) were studied. Study design: BMD of the lumbar spine and proximal femur were measured by dual-energy x-ray absorptiometry. Values were compared with those of healthy children of similar age, sex, and pubertal stage. Results: At diagnosis the mean BMD (standard deviation score [SDS]) was significantly reduced in both sites (P <.001) with a preferential loss of cortical bone (femoral BMD = –1.7 ± 1.0 SDS) rather than trabecular bone (lumbar spine BMD = –0.8 ± 1.1 SDS) (P =.003). Severe osteopenia (below –2 SDS) was found in 11 (42%) of 26 patients. Osteocalcin was significantly higher than in the control group (P <.0001), but other bone metabolism markers were normal. During treatment (n = 19) a significant gain in femoral (F = 14.7; P =.001) and lumbar spine (F = 5; P =.02) BMD (SDS) was observed, and none of the patients showed osteopenia. The annual percent change in the BMD values at the femoral (+23% ± 11% and +6% ± 4%, respectively, during the first and second years) and lumbar spine (+19% ± 9% and +6% ± 5%, respectively, during the first and second years) sites was greater during the first year than during the second year of treatment (P <.02 for femoral, P <.04 for lumbar spine). No significant age difference in BMD SD score or in BMD percent change values was observed. Osteocalcin returned rapidly to normal values, and all other bone metabolism markers remained in the normal range. Conclusions: In conclusion, severe osteopenia was observed at diagnosis in children with Graves’ disease but was rapidly corrected after 1 and 2 years of treatment. Initial reduced bone mass with high bone turnover caused by hyperthyroidism was corrected after 1 year of euthyroid conditions. (J Pediatr 2000;137:56-62)