Bone Disease after Kidney Transplantation

Abstract

Bone and mineral disorders occur frequently in kidney transplant recipients and are associated with a high risk of fracture, morbidity, and mortality. There is a broad spectrum of often overlapping bone diseases seen after transplantation, including osteoporosis as well as persisting high- or low-turnover bone disease. The pathophysiology underlying bone disorders after transplantation results from a complex interplay of factors, including preexisting renal osteodystrophy and bone loss related to a variety of causes, such as immunosuppression and alterations in the parathyroid hormone-vitamin D-fibroblast growth factor 23 axis as well as changes in mineral metabolism. Management is complex, because noninvasive tools, such as imaging and bone biomarkers, do not have sufficient sensitivity and specificity to detect these abnormalities in bone structure and function, whereas bone biopsy is not a widely available diagnostic tool. In this review, we focus on recent data that highlight improvements in our understanding of the prevalence, pathophysiology, and diagnostic and therapeutic strategies of mineral and bone disorders in kidney transplant recipients.

Keywords: Bone Diseases; Metabolic; Osteoporosis; Vitamin D; fibroblast growth factor 23; fracture; glucocorticoids; kidney transplantation; mineral metabolism; parathyroid hormone; renal osteodystrophy.

Figure 1.

Pathophysiology of bone loss and fractures before and after transplantation. BMD, bone mineral density; BMI, body mass index; FGF23, fibroblast growth factor 23; 1,25(OH)₂D, 1,25–dihydroxy vitamin D; PTH, parathyroid hormone; SHPT, secondary hyperparathyroidism.

Figure 2.

Management of mineral and bone disorders post-transplantation. The strength of recommendation is indicated as level 1 (we recommend), level 2 (we suggest), or not graded, and the quality of the supporting evidence is shown as A (high), B (moderate), C (low), or D (very low). ABD, dynamic bone disease; BMD, bone mineral density; DXA, dual x-ray absorptiometry; KDIGO, Kidney Disease Improving Global Outcomes; PTH, parathyroid hormone; SHPT, secondary hyperparathyroidism.