Bone Mineral Density in Transfusion Independent Thalassemia Patients.

Low bone mineral density (BMD) is commonly seen in regularly transfused thalassemia patients; however, there have been few reports for bone mineral density assessment in transfusion independent thalassemia patients. The present report includes the results of BMD assessments in patients with transfusion independent thalassemia who were referred to the bone density clinic through 2002–2006. BMD was evaluated by dual energy x-ray absorptiometry (DXA, Hologic Delphi A). A convenience sample of 24 patients (Females=15) with transfusion independent thalassemia were measured with a mean age of 22.1 ± 13.8 years. Subjects younger than 10 yrs old (n = 7) underwent scans for Lumbar spine (LS; L1-L4) and whole body (WB), patients ages 10–20 (n = 5) were assessed for LS, WB, and non-dominant hip, and for patients older than 20 (n = 12), LS and hip scans were completed. Z-scores specific for age and gender were generated using Zemel BS et al.(J. Bone Min Res 2004) database. Z-scores less than −2.0 were considered as low bone density. Calcium intake was assessed by a brief food frequency questionnaire. Past medical history, medications, history of fractures, and family history of osteoporosis were obtained by chart review and patient interview. Data is presented as Mean ± SD. T-test was used to assess differences in continuous variables. The mean LS Z-score (n = 24) was −1.5 ± 1.0 and the mean hip Z-score (n = 17) was −0.5 ± 1.1. Mean WB Z-score (n = 10) was −2.0 ± 1.2. There was a significant (p<0.001) difference between spine and hip Z-scores. Overall 46% had a Z-score less than −2.0. Thirty-three percent of patients have spine Z-scores of less than −2.0 and 25% spine Z-scores between −2.0 and −1.0. Average spine Z-score in patients younger than 10 years old (n=7) was −1.6 ± 0.5. In WB scans, 50% of the patients had WB Z-scores worse than −2.0. None of the young patients (5–9 yrs; n = 7) consumed inadequate intake of calcium (< 2/3 of RDA age specific) while 75% of patients ages 10–20 (n = 4) years old consumed inadequate intake of calcium (dietary + supplement). Neither spine nor hip Z-score was related to patients’ gender, age, and calcium intake. Two patients reported fractures in the past and two reported family history of osteoporosis. Six patients had delayed puberty and one has hypogonadism. Seven patients have short stature. This data suggests that low bone mass is not only a problem in transfused thalassemia patients, but is also observed in non-transfused patients. The significance and pathophysiology of low bone mass should be studied further in non-transfused patient population, especially in younger children.