Bone mineral metabolism in adults with beta-thalassaemia major and intermedia

Bone disease is an important cause of morbidity in older patients with beta -thalassaemia major and intermedia. We studied 27 women and 23 men with be ta -thalassaemia major (37) and intermedia (13) whose mean age was 32.3 +/- 9.7 years. Bone mineral density (BMD) of the lumbar spine, femoral neck an d distal radius was determined by dual-energy X-ray absorbiometry (DXA). Th e longitudinal change in BMD over a mean of 5.6 years was determined in 19 patients. Serum 25-hydroxyvitamin D, insulin growth factor-1 (IGF-1), bone formation markers bone-alkaline phosphatase, osteocalcin and the resorption marker urinary N-telopeptide cross-linked type 1 collagen (NTx) were deter mined. The BsmI vitamin D receptor (VDR) gene polymorphism was analysed. Re duced BMD (Z-score < -2) was present in 89%, 62% and 73% of patients in the spine, hip and radius respectively. Vitamin D deficiency was found in 62%, decreased IGF-1 in 72% and increased urinary NTx in 84% of patients. Serum IGF-1 correlated with spine and hip BMD (r = 0.4, r = 0.39, P < 0.01 respe ctively), and NTx correlated with the hip BMD Z-score (r = 0.35 P < 0.05). The mean annual percentage change in spine BMD was -1.36%. Patients with th e VDR BB genotype had lower spine BMD than patients with the bb genotype. I n conclusion, bone loss continues in adult thalassaemia patients and is ass ociated with increased bone resorption and decreased IGF-1. The BsmI VDR ge ne polymorphism is associated with osteopenia in thalassaemia.