Effects of Monthly Intramuscular High-Dose Vitamin D2 on Serum 25-Hydroxyvitamin D and Immune Parameters in Very Elderly Chinese Patients with Vitamin D Deficiency

Purpose Vitamin D deficiency is highly prevalent among the very elderly and is associated with a wide variety of clinical conditions other than musculoskeletal diseases. This study aims to ascertain the efficacy and safety of high-dose intramuscular vitamin D2 in very elderly Chinese patients with vitamin D deficiency.Methods Very elderly (aged 80 years or over) Chinese patients with vitamin D deficiency were recruited to receive monthly intramuscular injections of 600,000 IU vitamin D2 until their serum 25-hydroxyvitamin D (25(OH)D) reached ≥30 ng/mL. The serum levels of 25(OH)D2, 25(OH)D3, iPTH, BTMs, immune parameters, and other biochemical parameters were measured at baseline and one month after each dose.Results Of the 30 very elderly Chinese patients who had been recruited into the study, 27 (90.0%) had their vitamin D deficiency corrected, and 26 (86.7%) reached vitamin D sufficiency. The mean time (±SD) was 3.1 (±1.3) months for vitamin D deficiency to be corrected, and 6.1 (±0.8) months for vitamin D sufficiency to be reached. The mean (±SD) serum level of 25(OH)D2 increased from 0.69 (±1.51) ng/mL to 29.07 (±5.68) ng/mL, while the mean (±SD) serum level of 25(OH)D3 decreased from 9.82 (±2.75) ng/mL to 5.30 (±3.09) ng/mL (both P < 0.001). The total T cells in serum remained unchanged ( P > 0.05), and the CD4 and B cells (CD19+) were increased significantly (both P < 0.05). In addition, no significant change was observed in the serum levels of iPTH and BTMs.Conclusion Monthly intramuscular injection of 600,000 IU vitamin D2 is an effective and safe dosing regimen to reach vitamin D sufficiency and enhances immune function in the very elderly Chinese patients with vitamin D deficiency.