Background: Increased fracture rates are observed following renal transplantation compared with the general population. Risk factors include age, diabetes, dialysis vintage, immunosuppression, and bone and mineral abnormalities (1). Low serum phosphorus levels occur post-transplantation; however its relationship with fracture risk has not been evaluated.
Aim: To evaluate risk factors for fractures in renal transplant patients at a single tertiary referral centre.
Method: A retrospective cross-sectional analysis of 146 patients (75M, 71F) post-renal transplantation was performed. Aetiology of end stage renal disease (ESRD), dialysis vintage, parathyroidectomy history, immunosuppression regimen, Dual energy X-ray densitometry (DXA) parameters, biochemistry and fractures were documented from medical records/radiological reports. Statistical analyses included univariate and multivariate regression.
Results: Mean age of patients at time of DXA was 54 (±12) years, with a mean time post-transplantation of 6.7 years (±5.5). The most common cause of ESRD was diabetes (27%); 86% of patients were on long-term prednisolone and 7% had parathyroidectomy. In post-menopausal women and men, T-scores were osteopenic or osteoporotic at the femoral neck (FN), lumbar spine (LS) and total body (TB) in 75%, 37% and 49% of patients respectively. In premenopausal women, 19%, 15% and 8% had Z scores ≤ - 2 at the FN, LS and TB. 80 fractures occurred in 53 patients (36%), with 40 fractures occurring post-transplantation. Ankle/foot fractures were most common (48%). FN, TB T-scores and serum phosphate correlated with fractures in both univariate and multivariate regression analyses after adjusting for age, weight and gender (p=0.005, p=0.006 and p=0.001, respectively). The relationship between serum phosphorus and fracture remained significant independent of FN and TB T-scores, parathyroid hormone levels and parathyroidectomy status.
Conclusion: Fracture is common post-renal transplantation, as is osteopenia/osteoporosis at the FN and TB. Lower serum phosphorus levels are associated with fractures. This previously unreported observation requires further evaluation in prospective studies.