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Renal failure is associated with multiple metabolic changes in the bones resulting in deterioration of bone mass and bone quality.1,2 Although renal transplant improves the quality of life for recipients, these changes in bone health are associated with a high risk of fracture, at least during the first year posttransplant.3,4 The purpose of this review is to discuss the significance of mineral and bone disease in patients with chronic kidney disease, with a special emphasis on posttransplant osteoporosis. The prevalence of osteoporosis in posttransplant patients is estimated to be close to 30%. Furthermore, it has been shown that hip fracture in posttransplant patients is independently associated with a 3-fold increase in mortality. Transplant-related osteoporosis and fractures are related to both pre- and posttransplant risk factors (Table 28-1).
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Many patients undergoing transplant may already have low bone mineral density related to chronic kidney disease (CKD), vitamin D deficiency, increased fibroblast growth factor-23 (FGF-23), secondary hyperparathyroidism, hypogonadism, use of loop diuretics, and reduced physical activity. In others, preexisting glucocorticoid therapy and past history of smoking may also be responsible. It is well known that CKD results in an imbalance in bone remodeling in favor of bone resorption. The abnormal mineral metabolism in CKD and its effect on bone is considered to encompass a broad spectrum of disorders that are collectively named chronic kidney disease–mineral and bone disorder (CKD-MBD).6,7 Isolated renal osteodystrophy, one of the components of CKD-MBD, is defined by abnormal bone histology and can be divided into low bone turnover (adynamic bone disease) and high bone turnover states. Both states can lead to a decrease in bone strength and an increase in pathological fractures.7 Evaluation of patients with CKD for impending CKD-MBD and increased fragility fracture risk is recommended for patients with stage 3–5 CKD2 and certainly in patients on dialysis.9 Dual x-ray absorptiometry (DXA) is typically used for assessment of bone mineral density measurements as a gold standard modality.
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