#2823 High doses and levels of cholecalciferol for secondary hyperparathyroidism in hemodialysis patients

Abstract Background and Aims Vitamin D is crucial for musculoskeletal and general health. Low levels are associated with an increased risk of death and morbidity, including cancer, cardiovascular, autoimmune diseases and infections. In hemodialysis (HD) patients vitamin D deficiency plays additionally an important role in the pathogenesis of Chronic Kidney Disease–Mineral And Bone Disorder (CKD-MBD), including the development of secondary hyperparathyroidism (SHP). Determination of 25(OH)D levels in CKD patients and the administration of cholecalciferol according to the guidelines for the general population is recommended. The literature data show that therapy even with high doses of cholecalciferol appear to be safe and sufficient to increase 25(OH)D level 30 ng/ml in HD patients. However, the prevailing opinion is that PTH lowering with cholecalciferol in CKD is unproven and clinically insignificant. The aim of the study was to evaluate the efficacy (including PTH concentration) and safety of increasing vitamin D levels from the recommended 30 ng/mL to 75 ng/mL in HD patients treated with high doses of cholecalciferol. Method 22 HD patients (16 M, 6 F)), with an average age of 72.5 ± 13.03 years and 25(OH)D concentration 30–50 ng/mL were administered cholecalciferol at a therapeutic dose of 70,000 IU/week (20,000 IU + 20,000 IU + 30,000 IU, immediately after each dialysis session) to reach the target serum 25(OH)D level 75 ng/mL, but not longer than for 24 weeks. The baseline data on calcium, phosphate, 1,84 PTH, 25(OH)D and 1,25(OH)2D serum levels were compared with the data when 25(OH)D 75 ng/mL was achieved or when the highest 25(OH)D levels were noted. Results A significant decrease in 1,84 PTH levels was observed during the study (542.36 ± 420.87 vs 230.99 ± 386.22 pg/mL; p 0.005). No significant effect on calcium (8.91 ± 0.57 vs 9.03 ± 0.63 mg/dL; p = 0.23) and phosphate (4.6 ± 1.06 vs 4.81 ± 1.06 mg/dL; p = 0.93) concentrations was shown. There was also significant increase in 25(OH)D and 1,25(OH)2D levels (35.52 ± 8.26 vs 79.83 ± 21.38 ng/mL; p 0.005, and 13.38 ± 7.26 vs 25.56 ± 12.80 pg/mL; p 0.005, respectively). In the range of 25(OH)D levels 30-50 ng/mL 25(OH)D correlated positively with 1,25(OH)2D levels, r = 0.305. When 25(OH)D levels exceeded 50 ng/mL, there was negative correlation with 1,25(OH)2D levels (r = –0 .177 for 25(OH)D 50-75 ng/mL, and r = –0.262 for 25(OH)D 75 ng/mL). Conclusion Our study showed that the administration of high therapeutic doses of cholecalciferol to achieve 25(OH)D levels 75 ng/mL was safe, without the risk of hypercalcemia and hyperphosphatemia. Raising of 25(OH)D levels to the upper limit of the laboratory norm resulted in significant decrease in PTH levels. Cholecalciferol may be useful in the treatment of SHP in HD patients, but higher 25(OH)D levels seem to be crucial.