25-hydroxyvitamin D deficiency in renal transplant recipients

Bone disease after kidney transplantation is a common problem. The serum levels of the active vitamin D metabolite 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D] have been studied extensively. In contrast, there has not been much concern about the serum levels of 25-hydroxyvitamin D(3) [25(OH)D]. However, it is well recognized that serum levels of 1,25(OH)(2)D are often normal in vitamin D-deficient patients. Moreover, inadequate serum 25(OH)D may limit the extrarenal production of 1,25(OH)(2)D that could lead to increased risk of many chronic diseases.

We analyzed whether renal transplant patients were at a higher risk of 25(OH)D deficiency because of the consequence of their need to protect themselves from sun exposure.

We hypothesized that renal transplant recipients are at high risk to develop 25(OH)D deficiency. Serum 25(OH)D levels were analyzed in renal transplant patients with adequate renal function and in an age- and gender-matched control group (n = 31) at the end of winter. All renal transplant patients practiced solar UV-protection after transplantation. 25(OH)D levels were compared using a nonparametrical test (Wilcoxon rank sum test).

Serum 25(OH)D levels were significantly lower in renal transplant patients compared with controls (P = 0.007). Geometric mean (with 95% confidence interval) in renal transplant patients was 10.9 ng/ml (8.2-14.3) compared with 20.0 ng/ml (15.7-25.5) in the control group.

Renal transplant recipients are at high risk to develop 25(OH)D deficiency. Treatment with vitamin D is recommended to correct their vitamin D deficiency, which may help protect them from serious vitamin D deficiency-related health problems that include an increased risk for internal malignancies.