[Osteodystrophy in thalassemia major].

Subjects with thalassemia major frequently have bone disorders of debatable pathogenesis. We attempt here to analyze the relationships between siderosis and thalassemic osteodystrophy by assessing calcium-phosphorus balance, hormone-vitamin homeostasis, osteoblastic-osteoclastic activity parameters, and bone mineral density (BMD) in 30 patients with thalassemia major (16 males, 14 females, age range 17-30 years). We found a significant increase in ferritin (p < 0.001) and significant decreases in serum i-PTH, 25OHD3, 1.25(OH)2D3, osteocalcin, estradiol, testosterone and FT4 (p < 0.001) in both sexes. In all patients a net decrease of bone mineral density was documented (p < 0.001). These results were then submitted to linear regression analysis: positive correlations between BMD and FT3, testosterone, estradiol (p < 0.01), were documented, and an inverse correlation between osteocalcin and ferritin was confirmed. Our findings suggest that thalassemic osteodystrophy is the result of several inhibitory influences on osteoblastic activity and bone apposition (related to hormone deficits and siderosis) which are aggravated further by anemia, chronic hypoxia and red marrow expansion.