Terpos Osteoporosis and osteosclerosis in sickle cell / β - thalassemia : the role of the RANKL / osteoprotegerin axis

Bone involvement is the commonest clinical manifestation of sickle cell disease. The infarction of vertebral bone marrow and the presence of osteoporosis may produce collapse of the vertebrae with the typical fish mouth appearance. Marrow hyperplasia seems to be the most important pathogenetic factor for bone loss in patients with sickle cell disease. However, there is no information in the literature on the prevalence and etiology of osteoporosis in patients with double heterozygosity of sickle cell disease and β-thalassemia (HbS/β-thalassemia). The human skeleton is remodeled continuously through life. The receptor activator of nuclear factor-κB ligand (RANKL) is a potent enhancer of osteoclastogenesis, while osteoprotegerin (OPG) is the decoy receptor of RANKL. An imbalance of the RANKL/OPG ratio has been described in both postmenopausal and β-thalassemia majorinduced osteoporosis. The aim of the present study was to evaluate the bone mineral density (BMD) of HbS/β-thalassemia patients in parallel with markers of bone remodeling in an attempt to better understand the pathophysiology of bone disease in these patients. To our knowledge, such studies are not available in the literature.