Loss of bone mineral density in renal transplantation recipients

This study investigated the prevalence and contributing factors of loss of bone mineral density after renal transplantation among Turkish patients.

The study included 70 subjects, namely 50 males and 20 females of overall mean age of 36.94 ± 10.09 years. We measured femoral neck mineral density by dual-energy X-ray absorptiometry (DEXA). A T score above -1 was defined as a normal bone mineral density compared with T scores of -1.0 to -2.5 or below -2.5 which were defined as either osteopenia or osteoporosis, respectively.

At a median duration of 23 months after renal transplantation, osteopenia or osteoporosis was observed among 30 (42.9%) or 30 (42.9%) of the 70 patients, respectively. The mean body mass index (BMI) value was significantly higher among the normal than the osteoporotic group: 27.59 ± 4.66 kg/m(2) vs 24.18 ± 3.57 kg/m(2), respectively. However, no significant differences occurred in terms of BMI among the other groups. The amount of proteinuria was significantly lower in the normal than the osteopenic or osteoporotic group: (12.5 (range, 10.0-20.0); 105.0 (10.0-2800.0) or 215.5 (10.0-1880.0) mg/d (P = .001 and .004, respectively). In contrast, there was no significant difference between the amounts of proteinuria displayed by the osteopenic group and the osteoporotic group (P < .05)]. These patient groups showed no difference in age, gender, donor source, cause of end-stage renal disease (ESRD), pretransplant dialysis modality, duration of dialysis, use of a vitamin D preparation, immunosuppressive regimen, posttransplantation period, levels of iPTH or 25 hydroxy vitamin D3 (25OH vit D), exposure to tacrolimus or cyclosporine (CyA), calcium × phosphate product, serum albumin and hemoglobin content, creatinine clearance, or serum bicarbonate concentrations (P > .05). The T scores of the femoral neck correlated with BMI (r: 0.415; P = .001), 25OH vit D level (r: 0.268, P = .026), creatinine clearance (r: 0.273, P = .022), and serum glucose level (r: 0.349, P = .003). It inversely correlated with the amount of proteinuria (r: -0.263, P = .028), serum alkaline phosphatase level (r: -0.329, P = .005), and serum magnesium concentration (r: -0.252, P = .035). Upon multivariate analysis, BMI and 25OH vit D level were observed to be independent risk factors for loss of femoral mineral density.

Loss of bone mineral density is a common complication that correlates with low BMI values and decreased 25OH vit D levels as major risk factors for this problem.