ESA-SRB-AOTA 2019

Trabecular bone score is reduced in thalassaemia major (#561)

Nisal Punchihewa 1 , Phillip Wong 2 3 4 , Anne Trinh 2 3 4 , Frances Milat 2 3 4
  1. Clinical School, Monash University, Clayton, Vic, Australia
  2. Hudson Institute, Clayton, VIC, Australia
  3. Department of Endocrinology, Monash Health, Clayton, VIC, Australia
  4. Department of Medicine, Monash University, Clayton, VIC, Australia

Thalassaemia major (TM) is a condition of ineffective erythropoiesis requiring chronic transfusion therapy. This leads to severe iron overload and requires concomitant iron chelation therapy to reduce  end-organ complications. Osteoporosis, kidney stones and hypercalciuria are common and major cause of morbidity. Trabecular bone score (TBS) is a measure of bone texture and bone microarchitecture at the lumbar spine.

We conducted a retrospective cross-sectional study of patients with thalassaemia major at Monash Health, the centre for haemoglobinopathy in Australia. We investigated bone parameters using Dual energy X-ray absorptiometry (DXA) and TBS and documented fracture prevalence. Clinical and biochemical risk factors for bone disease were confirmed through the medical records. Non-parametric data was analysed using Mann U Whitney and logistic and linear regression models.

We analysed 71 subjects with TM receiving deferasirox (n=59) and deferoxamine (n=12).  The mean age was 44.4±10 (years) and 43% were male. TBS scores (L2-4) were  reduced compared to aged matched controls (1), male: 1.24 Z-scores at all sites were reduced: lumbar spine: -1.75 (-4.6 to 1.7), femoral neck: -1.10 (-4.8 to 1.0) and  total body: -1.0 (-4.4 to 1.5). Fractures were confirmed in 28% of subjects: non-vertebral (27.7%) vs spinal fractures (13.9%). Lumbar spine and femoral neck Z scores were significantly associated with fractures (P<0.05) but TBS was not.

Kidney stones were highly prevalent (40.6%) and spot urine calcium/creatinine ratio was elevated 0.95 (0.05 to 9.1) (Normal <0.5). Kidney stones were associated with non-vertebral fractures (P=0.03)  and lowTBS (P=0.006) after adjusting for urine calcium/creatinine ratio. Conventional DXA parameters were not significantly associated with kidney stones.

Abnormal bone microarchitecture, as measured by TBS is present in thalassaemia major. The significant association between kidney stones and TBS deserves further study given the established links between hypercalciuria, kidney stones and osteoporosis in thalassaemia major.