ESPE Abstracts

Background: People with thalassemia have decreased bone mineral density (BMD). Whereas a growing body of research has demonstrated associations between circulating bone markers and BMD in many conditions, such data in adolescents with alpha-thalassemia who required frequent blood transfusion (BT) are limited.

Objective: To evaluate the associations between measures of bone health and serum bone markers in adolescents with alpha-thalassemia who required frequent BT.

Methods: Adolescents with alpha-thalassemia were recruited from thalassemia clinic. Inclusion criteria were i) ages 10-21 years, ii) received blood transfusion ≥6 times/year, iii) regularly followed up in our clinic, iv) BMI z-score > -2 to < -2, and v) apparently healthy. Participants were excluded if they had uncontrolled conditions or received medications affecting bone metabolism. L1-4 spine (LS) and whole-body less head (WB) BMD were measured using Lunar Prodigy DXA. BMD z-score was converted using instrumental software. Trabecular bone score (TBS) was calculated using iNsight™ software to determine microarchitecture of the lumbar spine. Fasting serum osteocalcin, c-terminal telopeptide (CTX) and LDL-c, a recently emerged osteoclast inhibitor, were served as bone markers.

Results: Thirty-two participants were enrolled to the study [45% male, mean age (±SD) 14.2±3.0 years, height z-score -0.1±0.25, BMI z-score -0.1±1.2, Tanner stage 3.5±1.5, pre-transfusion hemoglobin (PTHb) 8.8±0.8 g/dL]. Twenty-five (78%) participants had hemoglobin H-Constant Spring. Average BT volume was 113±32 mL/kg/year. Mean TBS, LSBMD and WBBMD z-scores were -0.04±0.30, -1.45±1.11 and -1.23±0.78, respectively. The prevalence of BMD z-scores <-2 at both measured sites was 19%. PTHb correlated with TBS (r=0.491, P=0.008), however, the association was insignificant in regression models. Ferritin did not correlate with TBS, BMD at both sites nor serum bone markers. CTX z-score (β±SE: 0.31±0.13; P=0.032), but not OC z-score or LDL-c, was positively associated with LSBMD z-score independent of BMI and height z-scores, Tanner stage and 25OHD. However, the association became insignificant after further adjusting for PTHb (P=0.066). LDL-c (β±SE: -0.02±0.01; P=0.024) negatively and CTX (β±SE: 0.20±0.08; P=0.029) positively associated with WBBMD in the fully adjusted model.

Conclusions: Elevated CTX is associated with increased LSBMD and WBBMD in adolescents with alpha-thalassemia who required frequent BT. Further, we also found an association between LDL-c and WBBMD. Thus, LDL-c could be an alternative low-cost screening for bone health in this population.