#495 Effect of Vit D supplementation on bone mineral density in haemodialysis patients. A comparative study

Abstract Background and Aims Low serum 25(OH) vit D levels are usually observed in haemodialysis patients. In this population, vit D deficiency is associated with secondary hyperparathyroidism (SHPT) and low bone mineral density (BMD). Although, vit D supplements are routinely prescribed in haemodialysis patients, their exact role in preventing bone loss hasn't been studied thoroughly. The primary aim of this study was to estimate the effect of cholecalciferol (vit D3) use on BMD changes of haemodialysis patients. Secondary aim was to evaluate how parathyroid hormone (PTH), phosphorus and calcium levels are affected by vit D3 supplementation. Method Twelve (12) haemodialysis patients with low levels of serum vit D were included. All of them had their bone density measured with Dual - Energy X-Ray Absorptionmetry (DXA). The study population was then divided in two groups. Half of them (6 patients) received oral cholecarciferol (study group) and the rest continued with their standard treatment (control group). Initial dose of cholecalciferol was 25000 iu weekly and titrated upwards until 25 (OH) vit D levels were reaching 20 ng/ml. Then, cholecarciferol was continued in maintenance dose to keep vit D levels between 20 and 40 ng/ml. Thirty (30) months later, DXA was repeated in all patients. BMD in total hip region was evaluated. During the study period, phosphorus, calcium and PTH levels were measured monthly while 25 (OH) vit D levels were measured every three months. Results Patients’ mean age was 61.9 (±8.8) years. There were no differences in age, initial BMD, PTH or vit D levels between the two groups. Overall, initial mean vit D value was 8.5 ng/ml. At the end of the study, vit D levels had increased to 23.6 ng/ml in the study group while remaining unchanged in the control group. At the beginning of the study, mean BMD in the whole population was 0.742 gr/cm3 and it decreased by 0.042 gr/cm3 after 30 months. No differences in BMD change were observed between the two groups (ΔBMD was −0.057 versus -0.029 gr/cm3 in the study and control group respectively, p = 0.12). PTH levels were reduced in the study group and increased in the control group but the observed difference was not significant (p = 0.11). Phosphorus and calcium levels were not affected by vit D supplementation. Of note, three fractures were observed in the study group and one in the control group during the study period. Conclusion Vit D3 supplementation didn't seem to affect the rate of bone loss in haemodialysis patients, at least in the doses received and levels of 25 (OH) achieved above. Its exact effect in PTH levels as well as in the rate of bone fractures needs to be verified by larger studies.