Quantitative computed tomography is unreliable for measurement of bone mineral density in inadequately chelated adolescent patients with β-thalassemia major: A case-control study

Abstract

Utility of quantitative computed tomography (QCT) for assessment of bone mineral density (BMD) in patients with thalassemia is not fully established. Majority of patients with thalassemia in India receive suboptimal iron chelation. There is paucity of data on BMD in this population. Aim was to assess BMD by lumbar QCT in adolescent patients with transfusion dependent β-thalassemia major and compare with controls. Study was conducted prospectively, over 15 months. Single energy QCT was performed through first three lumbar vertebrae. Forty-five patients were enrolled (age: 10-19 years). Thirty-eight normal siblings of patients with thalassemia patients served as controls. Forty percent patients weighed <3rd percentile, 64% were stunted, and 40% had suboptimal sexual maturity scores. Eighteen (40%) patients were on iron chelation with deferiprone. Mean serum ferritin was 2,800 ± 1,473 ng/ml. Mean BMD (mg/cu mm) of cases and controls was 194.5 ± 27.1 and 170.4 ± 28.84, respectively (P = 0.0002). The mean BMD of patients with ferritin <2,000 ng/ml and those with a higher ferritin was 181.2 ± 14.9 and 196.7 ± 25, respectively (P = 0.07). The finding of increased BMD in patients with thalassemia is in stark contrast to published reports. Patients had several risk factors for low BMD, including growth retardation, delayed puberty, and iron overload. Single energy QCT of lumbar vertebrae is not reliable for measurement of BMD in inadequately chelated patients with β-thalassemia major. The deposition of iron in bone tissue may result in increased X-ray attenuation values of trabecular bone.