Authors (including presenting author) :
Chan KY (1) Au Yeung YC (1) Choi CH (1)
Affiliation :
(1) Department of Medicine, Queen Elizabeth Hospital
Introduction :
Osteoporosis is a frequent comorbidity in thalassemia patients, and is associated with a high lifetime fracture risk even in appropriately treated patients. The underlying pathophysiology is complex, with a variety of contributing factors. With the increasing life expectancy of thalassemia patients due to the advances in their treatment, the management of osteoporosis is challenging as this group of patients usually present at a young age and require lifelong treatment. Currently, guidelines for osteoporosis treatment in thalassemia major patients are limited. Individualized assessment and treatment may be important to provide better care to this group of patients.
Objectives :
The aims of this study were to characterize osteoporosis in transfusion-dependent thalassemia patients in our local centre and to identify the factors that are associated with bone fragility, in hope to gain a better insight into the pathophysiology of the disease and guide future treatment to prevent fracture in this patient group.
Methodology :
Adult thalassemia patients who required regular blood transfusion at the Hematology day ward in the Queen Elizabeth Hospital (QEH) were recruited to participate in this cross-sectional observational study. Osteoporosis was evaluated by means of bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) scan, bone turnover markers and review on the history of fractures. Trabecular bone score (TBS) was also measured in selected patients (n = 7). Medical records were reviewed and clinical assessment with history taking, physical exam, laboratory tests and imaging studies were arranged to look for risk factors associated with bone fragility.
Result & Outcome :
31 transfusion-dependent adult thalassemia patients were recruited in the study. Osteoporosis and low BMD was common in our local centre. 51.6% patients had their spine and/or hip T-score below the WHO criteria for osteoporosis of ≤ -2.5; and 48.4% had spine and/or hip Z-score < -2.0. Spine BMD was lower in patients who had history of fracture (0.681 vs 0.797 g/cm2, p = 0.006); and lower values were also seen in their spine and hip T-score and Z-scores. Degraded bone microarchitecture (TBS < 1.350) was found in all patients who had their TBS tested (n = 7). Risk factors associated with low BMD in thalassemia patients include inadequate hormonal replacement for hypogonadism, low IGF-1 levels and iron overload as indicated by low MRI cardiac T2* measurements. Hypogonadal patients with inadequate hormonal replacement had lower spine and hip BMD when compared with those who had adequate replacement (spine BMD: 0.705 vs 0.781g/cm2, p = 0.033; hip BMD: 0.592 vs 0.762 g/cm2, p = 0.013), and the duration of hypogonadism without hormonal replacement showed negative correlation with the spine and hip BMD (Spine BMD: r = -0.556, p = 0.001; Hip BMD r = -0.653, p < 0.001). Spine T-score was lower in patients who had IGF-1 levels below the normal range for age (-2.9 vs -2.3, p = 0.047). MRI myocardium T2* showed significant correlation with both the spine (r = 0.418, p = 0.024) and hip BMD (r = 0.487, p = 0.007). In conclusion, osteoporosis was common in transfusion-dependent thalassemia patients in our local centre. Lower BMD values on DXA scan were linked to an increased fracture prevalence. TBS may play a complimentary role to DXA scan by providing further information on bone quality. Timely identification and treatment of risk factors for osteoporosis is crucial, and pharmacological treatment should be considered in patients with established osteoporosis. The study results urge the formulation of a standardized protocol for screening of osteoporosis and its risk factors in thalassemia major patients in order to allow timely identification and treatment.
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