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.