Bone health evaluation of children and adolescents with homozygous β-thalassemia: Implications for practice

摘要

OBJECTIVE: Bone tissue is adversely affected in patients with homozygous β-thalassemia. The aim of this study was to find warning signs of bone loss in young patients with β-thalassemia and allow prompt therapeutic interventions. METHODS: Thirty-eight patients were studied, 20 boys and 18 girls, aged 5 to 18 years (median=14.13 y), on regular transfusions and chelation treatments. Their bone mineral density (BMD) was measured with dual x-ray absorptiometry. The recorded parameters were weight, height, bone age (BA), transfusion adequacy (mean fetal hemoglobin value), and chelation efficacy (mean ferritin value, compliance). Tanner stage was also evaluated: 8 prepubertal subjects (stage 1), 18 peripubertal subjects (stages 2 and 3), and 12 postpubertal patients (stages 4 and 5). Blood and urine samples were collected for biochemical analysis. RESULTS: Mean BMD z score was -1.56±1.25. Thirteen patients had normal BMD (z score >-1), 17 patients had low BMD (z score: -1 up to -2.4), and 8 patients had very low BMD (z score <-2.5). Low BMD was observed in patients older than 12 years and was associated with short stature (r=0.33, P=0.04), delayed BA (r=0.61, P=0.01), and increased bone formation markers. There was no correlation of BMD z score with sex, fetal hemoglobin value, ferritin, and compliance. Regarding Tanner stage, it was associated strongly with short stature (r=0.57, P=0.01), ferritin (r=-0.38, P=0.02), and compliance (r=0.58, P=0.01). CONLUSIONS: The decline in BMD may start early, even in the well-transfused patients. This study targets the young patients who are mostly at the risk for bone loss, that is short adolescents with delayed BA. Their prompt recognition in everyday practice is important, as they will need close monitoring of their BMD and metabolic bone profile. In addition, therapeutic interventions, such as adequate calcium intake and sunlight exposure, weight-bearing exercise and, in cases of vitamin D insufficiency, proper supplementation could be suggested.