MO579POST-TRANSPLANT HYPERCALCEMIA AND VITAMIN D SUPPLEMENTATION

Abstract

Abstract Background and Aims Post-transplant hypercalcemia is common after successful kidney transplantation in patients with chronic kidney disease (CKD) and can be partially explained by the side effects of concomitant therapy. We aimed to evaluate the prevalence of hypercalcemia among recipients of kidney transplant and its relationship with vitamin D supplementation. Method We performed a cross-sectional study of 236 patients underwent successful kidney transplantation in our clinic. Median age was 49 [Q1-Q3: 39; 58] years, mean estimated glomerular filtration rate (eGFR) was 51,1±21,8 ml/min/1,73 m2. Most of the patients received hemo- or peritoneal dialysis treatment, pre-emptive transplantation was performed in 6% cases. For those previously received dialysis, median duration of any type of dialysis was 21 [Q1-Q3: 11; 36] months. Median time after transplantation reached 42 [Q1-Q3: 19; 75] months. Target range for total serum Ca was defined according to National guidelines on CKD-MBD as 2,1 - 2,5 mmol/l. Results In our cohort median serum total Ca level was 2,41 [Q1-Q3: 2,36; 2,56] mmol/l. Hypercalcemia was encountered in 21% (7 of 33) cases during the first year after transplantation and in 30% (61 of 203) – after first year. Serum total Ca weakly correlated with iPTH (ρ= 0,282 [95%CI: 0,15; 0,4], р<0,0001), alkaline phosphatase (ρ=0,181 [95%CI: 0,05; 0,31], р=0,006) and total duration of renal replacement therapy (dialysis + transplantation) - ρ=0,2 [95%CI: 0,07; 0,32], р=0,002. We did not observe statistically significant correlations between serum total Ca and eGFR (p=0,132), total Ca level and time after transplantation (p=0,06). Total Ca levels did not differ in groups with different eGFR (p=0,04 in Kruskall-Wallis test, but no statistically significant differences after correction for multiply comparisons). Data on concomitant therapy were available for 230 patients. 173 of 230 recipients received any therapy of CKD-MBD. Of them, 123 patients took only active vitamin D (alfacalcidol), 33 patients received monotherapy with inactive vitamin D (cholecalciferol). 57 patients not taking any medications were the control group. Serum total Ca level varied significantly between groups (p=0,0006, Kruskall-Wallis test), being higher in patients supplemented with cholecalciferol - fig.1. Meanwhile, iPHT (p=0,171), serum phosphorus (p=0,563) and alkaline phosphatase levels did not differ in these three groups. Fraction of patients with normocalcemia was the lowest in cholecalciferol group (χ2, р=0,0018) - fig. 2. Conclusion We observed a high prevalence of hypercalcemia in kidney transplant patients, that was not associated with transplant function or time after transplantation. Our data suggest usage of active vitamin D to be safer than cholecalciferol to prevent hypercalcemia development in renal allograft recipients.