Abstract
Vitamin D insufficiency has been associated with reduced bone mineral density (BMD) in kidney transplant patients (KTRs). However, the efficacy of vitamin D supplementation on BMD remains poorly defined, especially for long-term KTRs. We aimed to investigate the effect of native vitamin D supplementation on the BMD of KTRs during a 2-year follow-up. Demographic, clinical, and laboratory data were collected. BMD was evaluated with standard DEXA that was performed at baseline (before vitamin D supplementation) and at the end of study period. BMD was assessed at lumbar vertebral bodies (LV) and right femoral neck (FN) by a single operator. According to WHO criteria, results were expressed as the T-score (standard deviation (SD) relative to young healthy adults) and Z-score (SD relative to age-matched controls). Osteoporosis and osteopenia were defined as a T-score ≤ −2.5 SD and a T-score < −1 and a > −2.5 SD, respectively. Based on plasma levels, 25-OH-vitamin D (25-OH-D) was supplemented as recommended for the general population. Data from 100 KTRs were analyzed. The mean study period was 27.7 ± 3.4 months. At study inception, 25-OH-D insufficiency and deficiency were recorded in 65 and 35 patients. At the basal DEXA, the percentage of osteopenia and osteoporosis was 43.3% and 18.6% at LV and 54.1% and 12.2% at FN, respectively. At the end of the study, no differences in the Z-score and T-score gains were observed. During linear mixed model analysis, native vitamin D supplementation was found to have a negative nitration with Z-score changes at the right femoral neck in KTRs (p < 0.05). The mean dose of administered cholecalciferol was 13.396 ± 7.537 UI per week; increased 25-OH-D levels were found (p < 0.0001). Either low BMD or 25-OH-vitamin D concentration was observed in long-term KTRs. Prolonged supplementation with 25-OH-D did not modify BMD, Z-score, or T-score.
Highlights
With increased graft and patient survival, bone loss after kidney transplantation is becoming increasingly prevalent [1]
The present study aimed to investigate the impact of prolonged 25-OH vitamin D supplementation on bone mineral density (BMD) in a cohort of long-term kidney transplant patients (KTRs), and, as secondary aims, to assess BMD and its potential association between BMD, demographic characteristics, and biochemical data
We showed that inactive vitamin D supplementation was not associated with changes in bone mineral density over a median follow-up period of 2 to 3 years in a real-life cohort of long-term KTRs not treated with bisphosphonate and/or calcio-mimetics and who had never been supplemented with 25-OH vitamin D
Summary
With increased graft and patient survival, bone loss after kidney transplantation is becoming increasingly prevalent [1]. Despite bone loss maybe being caused by immunosuppressive treatments [3] and a history of chronic kidney disease [4], vitamin D deficiency is regarded as a main causative factor, and supplementation is recommended. The latest Kidney Disease: Improving Global Outcomes (KDIGO) guidelines on mineral metabolism management [5] recommend BMD testing to guide treatment with inactive vitamin D, calcitriol, and/or antiresorptive agents; in addition, depending on the 25-OH vitamin D (25-OH-D) plasma level, vitamin D supplementation is suggested as it is in the general population. Accurate, widespread, non-invasive, cost-effective method for assessing bone mineral density (BMD), a surrogate of bone mass, is a DEXA scan [12]
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