Objective: Thalassaemia/haemoglobinopathy is a hereditary disease causing increased erythropoiesis and expansion of the bone marrow cavity. As a consequence, there is a reduction in trabecular bone tissue resulting in osteopenia/osteoporosis. The present study was performed to assess bone mineral density (BMD) in children and adolescents with beta-thalassaemia disease and to determine biochemical and hormonal changes that may affect BMD.
Methods: Forty-eight children and adolescents with beta-thalassaemia were divided into two groups, transfusion-dependent (TD) (n = 16) and transfusion-independent (TI) (n = 32). All patients were treated suboptimally. BMD was determined by dual-energy X-ray absorptiometry. Bone maturation was assessed by radiographic bone age (BA). Blood and urine samples were obtained for the determination of biochemical and hormonal profiles, which included PTH, 25-hydroxyvitamin D (25-OHD), osteocalcin, bone-specific alkaline phosphatase, IGF-1, fT4, TSH and urine deoxypyridinoline.
Results: Most of the patients were short and underweight, and they had delayed BA with mean Z-scores of -2.77 in the TD and -2.04 in TI groups. The mean Z-scores of BMD in the TD vs. TI groups of total body, radius, femoral neck and lumbar spine were -2.09 vs.-1.49, -0.73 vs. -0.54, -1.93 vs.-1.17 and -3.45 vs.-2.43, respectively. Although the means BMD values in the TD group were lower than those in the TI group, they were not significantly different. Mean serum IGF-1 levels were lower in the TD than the TI groups, 11.6 and 24.9 nmol/l, respectively (P < 0.05). Other biochemical and hormonal profiles did not differ between these two groups.
Conclusions: Patients with undertransfused severe beta-thalassaemia had more bone marrow expansion, lower serum IGF-1 levels and more delayed bone age than did patients with untransfused moderately severe beta-thalassaemia. Therefore, the severity of the disease appeared to be a primary factor for low bone mineral density in undertransfused patients in association with bone age delay and low serum IGF-1.