Vitamin D Deficiency in Kidney Transplant Recipients: Risk Factors and Effects of Vitamin D3 Supplements

Abstract

Introduction. The Kidney Disease Outcome Quality Initiative (K/DOQI) clinical practice guidelines in chronic kidney disease (CKD) give some recommendations about diagnosis and treatment of vitamin D deficiency. These guidelines may also be applied to renal transplant recipients. The aim of the present study was to assess the vitamin D status and the effects of vitamin D3 supplements among a cohort of kidney graft recipients. Patients and Methods. Five hundred nine renal transplant recipients with a follow-up of more than 12 months were included in this retrospective cross-sectional study. A total of 189 patients were treated with vitamin D3 supplements, 171 with calcitriol (0.25 or 0.5 g ϫ 3 weekly) and 18 with cholecalciferol (400 IU/d). Results. 25OHD deficiency was present in 38.3% of patients, insufficiency in 46.9%, and normal levels in 14.7%. There were no differences in the prevalence of deficiency or insufficiency between patients who were not treated or those who were treated with vitamin D3 supplements. Upon multivariate analysis, 25OHD concentrations correlated with gender, length of follow-up, season of 25OHD determination, iPTH and 1.25OHD concentrations, and treatment with ACEI/ARB (R 2 ϭ 0.17; P ϭ .000). Conclusions. 25OHD deficiency or insufficiency is frequent after renal transplantation even in sunny regions. The clinical significance of such a high prevalence of apparent 25OHD deficiency/insufficiency is unclear and requires further study.

Vitamin D and Renal Disease

“…Suboptimal VD levels are commonly detected in kidney transplant recipients (KTRs), with prevalence of VD sufficiency below 20% [69]. Similar findings were detected in our institution in patients with duration of kidney transplantation (KTx) more than 6 months (n = 289), [70], During winter-spring fall, during the annual nadir of 25VD, the share of VD sufficient KTRs follow-up in our center dropped to 2.59% [71].…”

Endothelial Dysfunction in Renal Transplant Recipients: Role of Vitamin D and Fibroblast Growth Factor-23

“…This may be related to pretransplantation prevalent traditional and nontraditional cardiovascular risk factors that can be aggravated by the effects of immunosuppressive drugs. Recent studies showed that vitamin D deficiency, which is very prevalent in the transplantation population [8,9], may have a role in endothelial dysfunction in patients with CKD besides its well-known effects on calcium and phosphorus metabolism [10,11].…”

Vitamin D and Organ Transplantation

“…In one study, transplant recipients, who were an average of 7 years post-transplant, had significantly lower levels of 25(OH)D than age-matched controls [43]; among transplant patients mean serum 25(OH)D was 10 ng/ml and one-third of patients had undetectable levels [43]. Factors associated with low 25(OH)D in renal transplant recipients include African-American race [46], female sex, measurement in autumn and winter months [46], recent transplantation [55], inadequate dietary vitamin D intake, reported in 87e91% of patients [56], proteinuria [57], and use of ACE inhibitors or aldosterone receptor blockers [55]. Persistent elevations in FGF-23 after kidney transplantation may result in lower calcitriol levels [58].…”

“…Vitamin D deficiency is common and severe in patients several years after kidney transplantation [43,46,55]. In one study, transplant recipients, who were an average of 7 years post-transplant, had significantly lower levels of 25(OH)D than age-matched controls [43]; among transplant patients mean serum 25(OH)D was 10 ng/ml and one-third of patients had undetectable levels [43].…”