Vitamin D status, bone mineral density, and inflammation in kidney transplantation patients

Vitamin D has immunomodulatory and anti-inflammatory activities in the healthy population and in various disease states. There are few data on the quantification of vitamin D status and inflammation with respect to changes in bone mineral density among renal transplantation patients. We analyzed the influence of vitamin D levels on allograft function and inflammatory status at the time of enrollment and at 1-year follow-up. Sixty-four renal transplant patients, including 38 males, showed an overall age of 38.61 +/- 1.05 years, had a mean graft age of 6.15 +/- 3.17 years. We excluded patients who had diabetes mellitus, chronic inflammatory disease, or chronic allograft nephropathy. We obtained pre- and posttransplantation serum samples and daily proteinuria on each patient. Measurements of bone mineral density were performed by dual-energy X-ray absortiometry. After enrollment, we followed the patients for 1 year. Thereafter we assessed serum creatinine, C-reactive protein, albumin, and spot urinary protein levels. The patients were divided into two groups based upon vitamin D levels: group I (n = 29), <20 microg/L versus group II (n = 35), >or=20 microg/L. There was no significant difference in intact parathyroid hormone levels between the two groups. Vitamin D level positively correlated with serum creatinine (r = .32, P = .01) and serum albumin levels (r = .28, P = .023) at the time of enrollment. At 1 year, patients in group I showed significantly higher creatinine (P < .001) and proteinuria levels (P < .05) than those in group II. Low vitamin D levels are not uncommon among renal transplant recipients. There was a significant association of vitamin D levels with renal allograft function. Low vitamin D levels may be a predictor of worsening of graft function and increasing proteinuria.