Effect of alendronate on early bone loss of renal transplant recipients

Tertiary and Postrenal Transplantation Hyperparathyroidism

Patients who have undergone kidney transplantation (KTx) (KTxps) are a distinctive population characterized by the persistence of some metabolic anomalies present during end-stage renal disease. Mineral metabolism (MM) parameters are frequently altered after KTx. These alterations involve calcium, phosphorus, vitamin D, and parathormone (PTH) disarrangements. At present, there is little consensus about the correct monitoring and management of PTH disorders in KTxps. This article presents the prevalence and epidemiologic and clinical impact of post-KTx hyper-PTH. The principal biochemical and instrumental investigations and the therapeutic options for these conditions are also reported.

Management of Post-transplant Hyperparathyroidism and Bone Disease

Significant advances in immunosuppressive therapies have been made in renal transplantation, leading to increased allograft and patient survival. Despite improvement in overall patient survival, patients continue to require management of persistent post-transplant hyperparathyroidism. Medications that treat persistent hyperparathyroidism include vitamin D, vitamin D analogues, and calcimimetics. Medication side effects such as hypocalcemia or hypercalcemia, and adynamic bone disease, may lead to a decrease in the drugs. When medical management fails to control persistent post-transplant hyperparathyroidism, treatment is a parathyroidectomy. Surgical techniques are not uniform between centers and surgeons. Undergoing the surgery may include a subtotal technique or a technique including total parathyroid gland resection with partial heterotopic gland reimplantation. In addition, there are possible post-surgical complications. The ideal treatment for persistent post-transplant hyperparathyroidism is the treatment and prevention of the condition while patients are being managed for their late-stage chronic kidney disease and end-stage renal disease.

Outcomes of bisphosphonate therapy in kidney transplant recipients: a systematic review and meta-analysis

Mineral and bone disorders that precede kidney transplantation are exacerbated in the post-transplant setting by tertiary hyperparathyroidism and immunosuppressive regimens. Bone mineral density (BMD) decreases following transplantation, leading to increased fracture risk. The effect of bisphosphonates on fracture is unknown. The aim of this study was to update estimates of change in BMD and fracture rates in bisphosphonate-treated kidney transplant recipients through meta-analysis. Studies comparing bisphosphonate therapy to standard of care were included if follow-up duration was more than 6 months. We performed random-effects meta-analysis to determine the effect of bisphosphonates on lumbar spine and femoral neck BMD and fracture rates. Bisphosphonates improved femoral neck and lumbar spine BMD compared with controls (0.055 g/cm(2) , 95% CI 0.012-0.099 and 0.053 g/cm(2) , 95% CI 0.032-0.074, respectively) without adversely affecting serum creatinine or calcium. This corresponded to an unweighted improvement in BMD of 6.0% and 7.4%, respectively. There was no difference in fracture incidence in the two groups. Bisphosphonate therapy in kidney transplant recipients is associated with a statistically significant improvement in BMD at the lumbar spine and femoral neck. There was no difference in fracture incidence. Bisphosphonates did not adversely affect allograft dysfunction or serum calcium levels.

Mechanism and Treatment Strategy of Osteoporosis after Transplantation

Osteoporosis (OP) has emerged as a frequent and devastating complication of organ solid transplantation process. Bone loss after organ transplant is related to adverse effects of immunosuppressants on bone remodeling and bone quality. Many factors contribute to the pathogenesis of OP in transplanted patients. Many mechanisms of OP have been deeply approached. Drugs for OP can be generally divided into "bone resorption inhibitors" and "bone formation accelerators," the former hindering bone resorption by osteoclasts and the latter increasing bone formation by osteoblasts. Currently, bisphosphonates, which are bone resorption inhibitors drugs, are more commonly used clinically than others. Using the signaling pathway or implantation bone marrow stem cell provides a novel direction for the treatment of OP, especially OP after transplantation. This review addresses the mechanism of OP and its correlation with organ transplantation, lists prevention and management of bone loss in the transplant recipient, and discusses the recipients of different age and gender.

Osteoporosis after renal transplantation

Bone loss and fracture are serious sequelae of kidney transplantation, associated with morbidity, mortality and high economic costs. The pathogenesis of post-transplantation bone loss is multifactorial and complex. Pre-existing bone mineral disease is responsible for a significant part, but it is aggravated by risk factors emerging after renal transplantation with immunosuppressive agents being one of the key contributors. The decrease in bone mass is particularly prominent during the first 6-12 months after transplantation, continuing at a lower rate thereafter. Bone mineral density measurements do not predict bone histology and bone biopsy findings reveal heterogeneous lesions, which vary according to time after transplantation. Currently, vitamin D and bisphosphonates are the most extensively tested therapeutic agents against this accelerated bone loss in renal transplant recipients. Both of these agents have proven effective, but there is no evidence that they decrease fracture risk. More studies are needed to examine the complex pathophysiologic mechanisms implicated in this population, as well as the effects of different therapeutic interventions on bone disorders after kidney transplantation.

Alendronate as an effective treatment for bone loss and vascular calcification in kidney transplant recipients

Kidney transplant recipients develop secondary osteoporosis induced by immunosuppressive medication, with a high risk of fracture, and abdominal aortic calcification (AC) is a known predictor of cardiovascular mortality. In this study of 12 stable kidney recipients, we estimated the preventive effect of bisphosphonate treatment on bone loss and progression of AC. We randomly divided the subjects into a treatment group with alendronate (group A: 5 subjects) and a control group (group C: 7 subjects). Group A patients received 35 mg/week of alendronate over 24 months, while group C patients were not administered with any bisphosphonates. Two major endpoints were established: (1) the time-dependent change in bone mineral density (BMD) estimated with DEXA and (2) progression of abdominal AC, calculated twice as an index (ACI) using computed tomography data. Over the 2-year study period, group A patients showed significantly increased BMD of 1.86 ± 0.85% (P = 0.015 versus baseline), and almost complete inhibition of ACI progression (38.2 ± 24.2% to 39.6 ± 24.3%), but group C patients showed a decrease in BMD decline with bone loss and progression of ACI (32.8 ± 25.0% to 37.8 ± 29.2%, P = 0.061). In conclusion, alendronate therapy was an effective treatment in kidney transplant recipients for secondary osteoporosis and vascular calcification as ectopic calcification. This clinical trial is registered with number JMA-IIA00155 of JMACCT CTR.

Oral alendronate can suppress bone turnover but not fracture in kidney transplantation recipients with hyperparathyroidism and chronic kidney disease

Post-transplantation bone diseases negatively affect the quality of life of solid organ recipients. Secondary or tertiary hyperparathyroidism is a frequent complication in kidney transplantation (KTx) recipients. Treatment with immunosuppressive agents including glucocorticoids can lead to deterioration in bone metabolism in these patients. In the present study, we explored the effects of a three-year treatment period with oral alendronate (ALN) in long-term KTx recipients. Post-KTx recipients were recruited (n = 24, M/F = 12/12, mean age 52.0 ± 7.8 years) into this study. All patients were prescribed methylprednisolone (4.07 ± 0.86 mg/day) with various immunosuppressive agents. Before treatment with oral ALN (35 mg/week), the mean concentrations of intact parathyroid hormone (iPTH) and 25-hydroxyvitamin D were 139.2 ± 71.4 pg/mL and 20.8 ± 4.1 ng/mL, respectively. After 36 months of ALN treatment, mean iPTH levels increased slightly (+20.9 %). Treatment with ALN reduced bone-specific alkaline phosphatase (-35.4 %), serum type I collagen N-terminal telopeptide (-31.2 %) and osteocalcin (-55.6 %) levels. ALN did not increase bone mass after 24 months. Four patients with the highest baseline iPTH levels suffered a clinical osteoporotic fracture during the 36-month ALN treatment period. Higher iPTH levels with chronic kidney disease (CKD) at baseline were associated with the incidence of new clinical fractures during ALN treatment. In conclusion, anti-resorptive therapy with ALN can suppress bone turnover even when iPTH concentration is elevated in long-term KTx recipients. However, hyperparathyroidism with CKD seems to be associated with new clinical fractures during ALN treatment.

Zoledronic acid versus alendronate for the prevention of bone loss after heart or liver transplantation

CONTEXT

The first year after transplantation is characterized by rapid bone loss.

OBJECTIVE

The aim of this study was to compare zoledronic acid (zoledronate) and alendronate for prevention of transplantation bone loss.

DESIGN AND SETTING

A randomized clinical trial was conducted at a transplantation center.

PATIENTS

The study included 84 adults undergoing heart or liver transplantation and a concurrently transplanted, nonrandomized reference group of 27 adults with T scores greater than -1.5.

INTERVENTIONS

Alendronate (70 mg weekly for 12 months) or one 5-mg infusion of zoledronate were both initiated 26 ± 8 d after transplantation.

MAIN OUTCOME MEASURES

The primary outcome was total hip bone mineral density (BMD) 1 yr after transplantation. Secondary outcomes included femoral neck and lumbar spine BMD and serum C-telopeptide, a bone resorption marker.

RESULTS

In the reference group, BMD declined at the spine and hip (P < 0.001). In the randomized groups, hip BMD remained stable. Spine BMD increased in the zoledronate group and did not change in the alendronate group; at 12 months, the 2.2% difference between groups (95% confidence interval, 0.6 to 3.9%; P = 0.009) favored zoledronate. In heart transplant patients, spine BMD declined in the alendronate and increased in the zoledronate group (-3.0 vs. +1.6%, respectively; between-group difference, 4.2%; 95% confidence interval, 2.1 to 6.3%; P < 0.001). In liver transplant patients, spine BMD increased comparably in both groups. Twelve-month C-telopeptide was lower in the zoledronate group than in the alendronate group (79 vs. 49%; P = 0.04).

CONCLUSIONS

One 5-mg infusion of zoledronate and weekly alendronate prevent bone loss at the hip and, in liver transplant patients, increase spine BMD. In heart transplant patients, spine bone BMD remained stable with zoledronate but decreased with alendronate.

CKD-mineral and bone disorder management in kidney transplant recipients

Kidney transplantation, the most effective treatment for the metabolic abnormalities of chronic kidney disease (CKD), only partially corrects CKD-mineral and bone disorders. Posttransplantation bone disease, one of the major complications of kidney transplantation, is characterized by accelerated loss of bone mineral density and increased risk of fractures and osteonecrosis. The pathogenesis of posttransplantation bone disease is multifactorial and includes the persistent manifestations of pretransplantation CKD-mineral and bone disorder, peritransplantation changes in the fibroblast growth factor 23-parathyroid hormone-vitamin D axis, metabolic perturbations such as persistent hypophosphatemia and hypercalcemia, and the effects of immunosuppressive therapies. Posttransplantation fractures occur more commonly at peripheral than central sites. Although there is significant loss of bone density after transplantation, the evidence linking posttransplantation bone loss and subsequent fracture risk is circumstantial. Presently, there are no prospective clinical trials that define the optimal therapy for posttransplantation bone disease. Combined pharmacologic therapy that targets multiple components of the disordered pathways has been used. Although bisphosphonate or calcitriol therapy can preserve bone mineral density after transplantation, there is no evidence that these agents decrease fracture risk. Moreover, bisphosphonates pose potential risks for adynamic bone disease.