**Author details**

**5.3. Vitamin D treatment after KTx**

42 A Critical Evaluation of Vitamin D - Clinical Overview

*5.3.1. Native vitamin D (cholecalciferol/ergocalciferol)*

risk, cancer prevalence, and mortality after KTx [82].

*5.3.3. Treatment monitoring in transplant recipients*

*5.3.2. Calcitriol/vitamin D analogs*

ment in KTRs.

3 months posttransplant.

**6. Conclusion**

The influence of vitamin D treatment after KTx was mainly assessed for its effect on biochemical abnormalities in calcium phosphorus metabolism. The data about the effect on fracture risk, bone density, and pleiotropy are still insufficient. Guidelines are available only for the first posttransplant year. The data for the treatment after the first year are insufficient [21].

Cholecalciferol supplementation effectively suppressed PTH in renal transplant patients [101]. A meta-analysis performed by KDIGO showed improved bone density in patients with cholecalciferol-/ercalciferol-treated KTRs versus KTRs without VD supplementation [21]. The suggested cholecalciferol dose corresponds with the recommended dose for the general population [21]. As no data are present for patient-targeted endpoints such as fracture risk, no guidelines are available for this issue. Similarly, no specific recommendations can be given for VD pleiotropy. However, there are two large randomized trials assessing cholecalciferol supplementation in KTRs and its effect on renal graft function, NODAT incidence, infection

Treatment with calcitriol/VDAs in renal transplant patients with CKD stages 3T–5T is based on the same principles as in patients with CKD stages 3-5 (GFR below 60 ml/min). The reason for accepting the same approach is the paucity of RCTs in KTRs treated with calcitriol/VDAs [21]. However, certain considerations should be taken into account. The most important one is the high prevalence of persistent hyperparathyroidism and hypercalcemia after KTx. If the PTH levels do not resolve parathyroidectomy should be considered in these cases. As already mentioned, further research is needed in terms of pleiotropic effects of calcitriol/VDA treat-

Similarly to pretransplant CKD stages, monitoring calcium, phosphate, PTH, bone AP, and 25 hydroxyvitamin D depends on the renal function, the trend in biochemical abnormalities, and the intervention performed. Still, certain frequencies are suggested (**Table 4**) after the first

Vitamin D metabolism is significantly impaired at different levels in the early stages of renal disease. The influence of the abnormalities spans beyond calcium-phosphorus metabolism, having impact on mortality, cardiovascular morbidity, cancer risk, renal protection, etc. Thus, VD metabolites have pivotal role in controlling a great number of intracellular pathways that are impaired in renal disease contributing to poorer patient outcomes. Jean J. Filipov\* , Borelli K. Zlatkov and Emil P. Dimitrov

\*Address all correspondence to: jeanphillipov@yahoo.com

Department of Nephrology and Transplantation, Clinical Center of Nephrology, University Hospital "Alexandrovska," Medical University – Sofia, Bulgaria
