Bone and Mineral Disease in Kidney Transplant Recipients

Abstract

After kidney transplantation, mineral and bone disorders are associated with higher risk of fractures and consequent morbidity and mortality. Disorders of calcium and phosphorus, vitamin D deficiency, and hyperparathyroidism are also common. The epidemiology of bone disease has evolved over the past several decades due to changes in immunosuppressive regimens, mainly glucocorticoid minimization or avoidance. The assessment of bone disease in kidney transplant recipients relies on risk factor recognition and bone mineral density assessment. Several drugs have been trialed for the treatment of post-transplant mineral and bone disorders. This review will focus on the epidemiology, effect, and treatment of metabolic and skeletal derangements in the transplant recipient.

Keywords: kidney transplantation series; mineral metabolism.

Figure 1.

Pretransplant and post-transplant risk factors for osteoporosis. BMI, body mass index.

Figure 2.

Risk-based approach to mineral and bone disease (MBD) management after kidney transplantation. *Parathyroidectomy should be preferred over cinacalcet in patients who require long-term (>12-month) management of MBD abnormalities, including persistent hypercalcemia, nephrocalcinosis/nephrolithiasis, or high bone turnover states resistant to medical therapies. ^Bone mineral density (BMD) by dual energy x-ray absorptiometry (DXA) is performed at 2–4 months post-transplantation in accordance with Kidney Disease Improving Global Outcomes guidelines. The authors recommend that BMD evaluation by DXA should be repeated yearly until BMD has stabilized and as long as antiresorptive/anabolic agent is being administered. Following stabilization or discontinuation of treatment, BMD can be assessed every 3–5 years. ^#Bone turnover markers in clinical practice are limited to the following: parathyroid hormone (PTH) and bone-specific alkaline phosphatase (BSAP). Low turnover markers refer to PTH less than two times the upper limit of normal and BSAP less than the lower limit of the reference range. High turnover markers refer to PTH greater than two times the upper limit of normal and BSAP greater than the median of the reference range. If PTH and BSAP are discordant, then a bone biopsy is recommended to guide therapy. LLN, lower limit of normal; ULN, upper limit of normal; VDRA, vitamin D receptor analog.