E-Poster Presentation 30th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2020

Bone loss is persistent in young adults with transfusion-dependent thalassemia major and is associated with urinary calcium excretion and haemoglobin increment over time (#98)

Madhuni Herath 1 2 3 , Pierre-Antoine Dugue 4 , Zane Kaplan 5 6 , Jasna Aleksova 1 2 3 , Nisal Punchihewa 2 7 , Frances Milat 1 2 3 , Phillip Wong 1 2 3
  1. Department of Endocrinology, Monash Health, Melbourne, VIC
  2. Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research, Melbourne
  3. Department of Medicine, School of Clinical Sciences, Monash University, Melbourne, Australia
  4. Precision Medicine, School of Clinical Sciences, Monash University, Melbourne, Australia
  5. Department of Haematology, Monash Health, Melbourne, Australia
  6. Inherited Blood Disorders Clinic, Monash Health, Clayton, VIC, Australia
  7. Clinical School, Monash University, Melbourne, VIC, Australia

Background: Thalassaemia major (TM), an inherited disorder of ineffective erythropoiesis, requires lifelong transfusions and iron chelation therapy. Osteoporosis is a complication of thalassaemia; chelation therapy and hypercalciuria have been associated with reduced areal bone mineral density (aBMD) in cross-sectional studies.

Methods: An open-label, prospective study was conducted to investigate the effect of hydrochlorothiazide and iron chelation (deferasirox or deferoxamine) on aBMD in TM. Enrolled patients (n=111) were followed for eight years and aBMD was measured by dual energy x-ray absorptiometry (DXA) biennially. Time was assessed as a categorical variable. Patients with >1 missing DXA result were excluded; 92 patients were analysed. Mixed model and linear regression analyses were performed.

Results:  There were 44 (48%) men: mean baseline age was 38±9 years, mean haemoglobin and ferritin levels were 103g/L (normal 115-165g/L) and 1248µg/L (normal 30-600µg/L) respectively. Seventy-two patients (78%) received deferasirox; 20 (22%) received deferoxamine. Twenty-five (27%) patients were treated with hydrochlorothiazide (12.5mg or 25mg). At the study completion eleven (12%) patients sustained fractures, 33 (36%) were hypogonadal and 15 (16%) had exposure to anti-resorptives.

Femoral neck (FN) aBMD declined (right: -0.0048g/cm2/year, 95%CI [-0.0067, -0.0028], P=3x10-6; left: -0.0038g/cm2/year, 95%CI [-0.0056, -0.0020] P=4x10-5) independent of chelation therapy. Urine calcium/creatinine ratio was associated with decline in FN aBMD (-0.011g/cm2 [-0.022, -0.001] per unit change, P=0.04) but treatment with hydrochlorothiazide was not. An increase in haemoglobin over follow-up, but not ferritin, was associated with decline in aBMD at the LFN and lumbar spine (-0.0016g/cm2 [-0.0029, -0.0004], P=0.01, and -0.0018g/cm2 [-0.0034, -0.0004], P=0.02, respectively).

Conclusion:  Increased urine calcium/creatinine was associated with bone loss at the FN but the study was underpowered to assess hydrochlorothiazide effect. The association of haemoglobin increment over time with bone loss may have implications for long term transfusion therapy targets in TM and deserves further study.