Trabecular and integral bone density in adults with sickle cell disease

Sickle cell disease (SCD) is a hereditary disorder of hemoglobin synthesis that can affect the skeletal system owing to accelerated hematopoiesis and/or bone infarction. Additionally, several studies have suggested that a low bone mass is associated with SCD, partly because of adverse effects on growth and development. The few previous studies of bone mineral density (BMD) in these patients have utilized dual-photon or dual-energy x-ray absorptiometric (DXA) techniques, which may have limited value in this population because it cannot correct for differences in bone size. We undertook a study of BMD in the forearm of patients with sickle cell disease using peripheral quantitative computed tomography (QCT), which provides a measure of volumetric bone density for the trabecular bone component as well as cortical and trabecular bone together. We studied 32 African-American SCD patients with no known history of bone infarction in the wrist, and compared them with data from healthy African-American volunteers. We found a 13% lower integral (cortical and trabecular) BMD in the SCD patients (p=0.001), but no difference in trabecular BMD (p=0.40 for males, 0.32 for females). We hypothesize that the maintenance of trabecular BMD in the wrist may be related to the persistence of metabolically active red marrow in this region in adults with SCD.