Cholecalciferol supplements improve vitamin D deficiency in renal transplant recipients

Most renal transplant recipients display vitamin D deficiency or insufficiency. The KDIGO guidelines suggest that this deficit should be treated as in the general population. Since there are few studies about the effects of cholecalciferol in de novo renal transplant recipients, we sought to assess these effects in long-term kidney graft recipients. Among 37 renal transplant recipients (19 males, 18 females) at a mean of 105±82 months posttransplantation, vitamin D insufficiency or deficiency was treated with cholecalciferol (400-800 IU/d) plus calcium supplements (600-1200 mg/d of elemental calcium). These subjects were compared with 37 untreated recipients for a period between 6 and 12 months. At baseline, there were no differences between the groups in age at transplantation, sex, length of follow-up after grafting, function measured by estimated glomerular filtration rate (44.4±16.8 treated vs 42.0±15.0 mL/min/1.73 m2 untreated; P=.527); iPTH (157±103 treated vs 176±118 pg/mL untreated; P=.461); 25OHD (14.7±4.7 treated vs 15.7±9.7 ng/mL untreated; P=.584); or 1.25OHD (34.1±26.0 treated vs 34.0±13.0 pg/mL untreated; P=.950). When compared with baseline values, iPTH (157±103 vs 144±89 pg/mL; P=.11) and 1.25OHD levels at 6 months (34.1±26.0 vs 35.9±26.3 pg/mL; P=.282) showed no change but 25OHD levels (14.7±4.7 vs 22.6±7.4 ng/mL; P=.000) and phosphate tubular reabsorption (64%±17% baseline vs 69%±14% at 6 months; P=.030) were increased in the treated patients. There were no differences in the parameters studied in untreated patients. Among the 27 recipients followed at 12 months, iPTH was decreased compared with baseline values (157±103 vs 124±62 pg/mL; P=.024) and 25OHD remained stable with respect to the values at 6 months (21.1±5.3 ng/mL). No adverse effects of cholecalciferol were observed such as those to increase urinary calcium excretion. Low doses of cholecalciferol improved vitamin D status and decreased iPTH levels at 12 months. Higher doses than those used in our study are needed to increase serum 25OHD concentrations above 30 ng/mL.