Bone Mineral Density Changes in Long-Term Kidney Transplant Recipients: A Real-Life Cohort Study of Native Vitamin D Supplementation

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.

Drugs associated with incident fragility fractures in kidney transplant recipients

“…With regard to bisphosphonates, most of the relevant studies (including meta-analyses) have found that the use of bisphosphonates by kidney transplant recipients is associated with a BMD gain [ 42–44 ] but not with a lower risk of incident fractures [ 42–44 ]. Concerning vitamin D, a recent study did not find an increase in BMD after 2 years of vitamin D supplementation [ 45 ]; this is also consistent with the literature data [ 46 ]. On the same lines, there is no evidence to suggest that vitamin D supplementation reduces the fracture risk [ 46 ].…”

Persistent hyperparathyroidism in long-term kidney transplantation: time to consider a less aggressive approach

“…On the contrary, a recent analysis of 259 patients with a mean PTH of 129 pg/ml at 9 months after transplantation revealed a relationship between the duration of steroid use but not PTH level with the changes in the BMD after 2 years [20]. Similarly, among patients with a transplant vintage of 6 years and an average PTH of 83 pg/ml, no relationship between PTH level with WHO criteria for osteopenia and osteoporosis at the lumbar spine and the femoral neck was observed [21 ▪▪ ]. A prospective observational study of 518 de-novo kidney transplant recipients revealed that PTH at the time of transplantation was not predictive of incident fracture after 5 years [22].…”

Associations between lumbar bone mineral density, serum 25-hydroxyvitamin D and history of kidney stones in adults aged 30–69 years in the USA (NHANES 2011–2018)

“…The current findings do not support the beneficial effects of high-dose vitamin D supplements on bone health, which may even confer a substantial reduction in BMD, risk of falls, fractures or a small increase in myocardial infarction 36. Excluding people with normal renal function, in kidney transplant recipients, a recent study showed that supplementation with inactive vitamin D did not modify the urinary calcium nor the BMD, Z-score or T-score at lumbar bodies and the femoral neck in kidney transplant recipients 37. According to the current available evidence, the benefits of vitamin D supplementation in humans are more biased towards a ‘U-shaped’ association.…”