P1513: LOW VITAMIN D LEVELS ARE ASSOCIATED WITH INCREASED CARDIAC IRON UPTAKE IN THALASSEMIA MAJOR.

Abstract

Background: Decreased vitamin D (VitD) levels stimulate the expression of the transmembrane L-type voltage-dependent calcium channels (LVDCC), which, in addition to calcium, absorb iron. However, there is little and controversial data on the correlation of VitD levels with cardiac iron. Aims: We investigated the association between vitamin D levels and cardiac iron and function in thalassemia major (TM) patients. Methods: We considered 278 TM patients (39.04±8.58 years, 56.8% females), consecutively enrolled in the Extension-Myocardial Iron Overload in Thalassemia Network. Myocardial iron overload (MIO) was quantified using a T2* segmental approach. Left ventricular (LV) function parameters were quantified by cine images. Measurement of serum 25(OH)D was carried out using a chemiluminescent immunoassay. Results: Vitamin D supplements were taken by 61.4% of our patients. VitD levels were deficient (<20 ng/dl) in 107 (38.5%) patients, insufficient (20–30 ng/dl) in 96 (34.5%) patients and adequate (>30 ng/dl) in 75 (27.0%) patients. Patients with deficient vitD levels were significantly younger than patients with adequate (36.96±7.64 yrs vs 41.26±8.19 yrs; P<0.0001) as well as insufficient vitD levels (36.96±7.64 yrs vs 39.63±9.39 yrs; P=0.042) while no difference was detected in male to female ratio. MIO (global heart T2*<20 ms) was significantly more frequent in patients with deficient VitD than in patients with adequate and insufficient VitD levels (Figure). Patients with deficient vitD levels had a significant higher risk of MIO than patients with adequate vitD levels (odds ratio-OR=20.62, 95%CI=2.67-153.72; P=0.004) and patients with insufficient VitD levels (OR=8.49, 95%CI=2.46-29.29; P=0.001). At receiver operating characteristic curve analysis, a vitD level≤ 17.3 ng/dl predicted MIO with a sensitivity of 81.5% and a specificity of 75.3% (P<0.0001). The area under the curve was 0.79 (95% confidence interval: 0.74–0.84). Compared to patients with normal VitD levels, patients with deficient vitamin levels showed significantly higher LV end-diastolic volume index (87.61±19.19 ml/m2 vs 79.17±14.27 ml/m2; P=0.003) and LV mass index (63.39±13.55 g/m2 vs 57.45±12.90 g/m2; P=0.006). The LV ejection fraction tended to be lower in patients with VitD deficiency, but no statistical difference versus the other groups was detected. Image:Summary/Conclusion: In thalassemia major vitamin D deficiency is associated with and increased risk of cardiac iron overload. Periodic and regular assessment of VitD levels can be useful in the prevention not only of bone disorders but also of cardiac iron accumulation and subsequent overt dysfunction.