Calcitriol did not improve bone quality and strength in kidney transplant patients on corticosteroid-sparing immunosuppression: Study

A new study published in the Journal of Bone and Mineral Research showed that calcitriol administration to kidney transplant recipients on corticosteroid-sparing immunosuppression increased the risk of hypercalcemia but did not stop bone loss. Therefore, if vitamin D levels are sufficient, regular usage might not be required.

A considerable proportion of individuals who get kidney transplants have poor bone mineral density (BMD). Because of the effects of medications and changes in metabolism, kidney transplant patients are more likely to experience bone loss. According to prospective studies, bone loss occurs quickly in the first 6 months following renal transplantation (RT). Thus, Pascale Khairallah and colleagues thus undertook this study with the idea that by inhibiting PTH and bone remodeling, calcitriol treatment during the first year after transplantation would preserve the cortical skeleton in recipients treated without corticosteroids.

For 12 months following transplantation, 67 patients aged ≥18 years on an immunosuppressive regimen that spares corticosteroids were randomized to receive daily calcitriol 0.5 mcg or a placebo in this study. As determined by HR-pQCT, the main outcome was the percentage change in cortical density at the radius and tibia from before to after calcitriol administration in comparison to a placebo.

DXA was used to measure areal BMD. HR-pQCT was used to evaluate microarchitecture, cortical and trabecular volumetric BMD, and total estimated bone strength. At baseline, 1 month, and 12 months, blood samples were collected for bone metabolic indicators. The goal of every main analysis was to treat. Hypercalcemia and the development of vascular calcifications were evaluated for safety.

A total of 29 individuals got a placebo, and 32 people received calcitriol, where 27participants of each group finished the trial. The majority of participants were Caucasian men. All locations' baseline Z-scores were within 0.5 SD of the population average. Serum levels of bone markers, microarchitecture or bone strength, areal BMD, and volumetric BMD did not change between groups at 12 months after transplantation.

Serum bone indicators showed a reduced anabolic response over a 12-month period in participants when compared to those without bone loss. The calcitriol group had greater levels of hypercalcemia than the placebo group (p<.001). Scores for arterial calcification did not change. Overall, while calcitriol did not increase bone strength or quality in kidney transplant patients on corticosteroid-sparing immunosuppression, it was linked to increased rates of hypercalcemia in this research.

Reference:

Khairallah, P., Cortez, N. E., McMahon, D. J., Sammons, S., Agarwal, S., Crew, R. J., Cohen, D. J., Dube, G. K., Mohan, S., Chang, J.-H., Morris, H. K., Fernandez, H. E., Aponte, M. A., Adebayo, A. O., Aghi, A., Zaninotto, M., Plebani, M., Tripepi, G., Gallieni, M., … Nickolas, T. L. (2025). Calcitriol supplementation after kidney transplantation: Results of a double-blinded, randomized, placebo-controlled trial. Journal of Bone and Mineral Research: The Official Journal of the American Society for Bone and Mineral Research. https://doi.org/10.1093/jbmr/zjaf044