Bone turnover, areal BMD, and bone microarchitecture by second-generation high-resolution peripheral quantitative computed tomography in transfusion-dependent thalassemia

Abstract

Thalassemic osteopathy includes low bone mass and impaired bone microarchitecture. We aimed to evaluate the prevalence and determinants of bone quantity (osteoporosis) and quality (microarchitecture) in a cohort of adult patients with transfusion-dependent thalassemia (TDT). Patients with TDT (n = 63) and age- and BMI-matched controls (n = 63) were recruited in the study. Areal bone mineral density (BMD) was measured using DXA Hologic scanner. P1NP and β-CTX were estimated by electrochemiluminescence assay. Bone geometry and volumetric BMD (vBMD) were estimated by second-generation high-resolution peripheral quantitative computed tomography. Bone turnover marker β-CTX was significantly lower in the TDT group, but there was no difference in P1NP levels. Low bone mass (Z ≤ -2) was present in greater proportion of patients both at lumbar spine (LS) (54 vs 0%; p = .001) and femoral neck (FN) (33 vs 8%; p = .001). Hypogonadism was associated with low BMD at FN (OR 10.0; 95% CI, 1.2-86; p = .01) and low hemoglobin with low BMD at LS (OR 1.58; 95% CI, 0.96-2.60; p = .07). The mean trabecular bone score was also significantly lower in patients compared with controls (1.261 ± 0.072 vs 1.389 ± 0.058). Total, cortical and trabecular vBMD were significantly lower in cases than controls. The trabecular number and cortical thickness were significantly lower and trabecular separation higher in cases than controls. Adults with TDT have significantly lower areal, cortical and trabecular vBMD. The bone microarchitecture is also significantly impaired in terms of lower number and wider spacing of trabeculae as well as lower cortical thickness and area at both radius and tibia.

Keywords: HR-pQCT; bone microarchitecture; ferritin; iron overload; osteoporosis; thalassemia.

Graphical Abstract

Figure 1

Panel of photographs depicting the cortical microarchitecture in a patient with thalassemia and an age-and BMI-matched control. The top panel depicts the significantly lower cortical thickness and volumetric BMD at the radius (a) and tibia (c) in the patient versus the control at both radius (b) and tibia (d).

Figure 2

Panel of photographs depicting the trabecular microarchitecture in a patient with thalassemia and an age-and BMI-matched control. The top panel shows reduced trabecular number and increased separation at the radius in the patient (a) versus the control (b) at the radius. Similarly, more significant changes are noted at the tibia in the patient (c) as compared with the control (d).

Figure 3

Photomicrographs of iliac crest biopsy in a patient with β-thalassemia major who succumbed to septic shock showing (a) reduced number and thinning of bony trabeculae and bone mass, (b) fragmentation of bony trabeculae with widened marrow spaces, (c) reduced lamellations, and (d) control showing well-spaced and normal thickness of bony trabeculae (hematoxylin & eosin stain).