Background: Calcitriol-l,25-dihydroxyvitamin D3, has multiple biological and
immunomodulatory effects at the cellular level. In animals, the efficacy of calcitriol in prolonging allograft survival was demonstrated. Deficiency of calcitriol is associated with cardiovascular and cancer morbidity in general population. The aim of this study was to assess calcitriol status in renal allograft recipients and its impact on the outcome of transplantation.
Material/Methods: The study entailed 90 patients transplanted between 2002-2005. All patients received supplementation of Vitamin D before transplantation. The calcitriol levels were determined on the 3[sup]rd[/sup] day and at the 1[sup]st[/sup], 6[sup]th[/sup], 12[sup]th[/sup] and 18[sup]th[/sup] month after transplantation by radioimmunoassay.
Results: Severe calcitriol defi ciency (7.3±3.3 pg/ml) was found in 83% of
patients immediately after transplantation. From the 1[sup]st[/sup] to 12[sup]th[/sup] month the level increased almost 3-fold, and then remained constant at 18[sup]th [/sup]month. Only 50% of recipients reached a level >30pg/ml (similar as healthy control), and the remaining recipients had 17.2±6.4 pg/ml. A high incidence of DGF occurred in patients with calcitriol deficiency (44% vs. 6%). Negative correlation of initial calcitriol level with serum creatinine on the 3[sup]rd[/sup] day and 6[sup]th[/sup] month (p<0.03) was found. Similarly calcitriol level at 1[sup]st [/sup]month negatively correlated with creatinine levels at months 1 through 18 (p<0.01). Poor outcome was observed mainly in patients with deficiency of calcitriol: 2 developed cancer; 2 lost grafts in 1[sup]st [/sup]year, 3 in 2[sup]nd[/sup] year; 4 died due to cardiovascular events.
Conclusions: Deficiency of calcitriol in renal allograft recipients was highly prevalent. Patients with calcitriol deficiency were at higher risk of DGF, and were more likely to lose their graft. This work points out at the necessity of adequate supplementation of vitamin D3 before and after transplantation.

Keywords: Immunosuppression, Kidney Transplantation