Effect of teriparatide on early bone loss after kidney transplantation

Bone health and fracture prevention after kidney transplantation

Changes in bone health and strength are common after kidney transplantation and can lead to an increased risk of fracture. This has implications for morbidity, mortality and renal allograft survival. This review will focus on the changes that occur in bone health and fracture risk after kidney transplantation and examine the evidence available to guide diagnostic and therapeutic decisions with the aim of fracture prevention.

Teriparatide as Treatment for Severe Osteoporosis in Lung Transplant Recipients

Osteoporosis and osteopenia are common in lung transplant (LTx) recipients, with a significantly increased incidence compared to other non-lung solid organ transplant patients. Despite high fracture rates, including in patients treated with antiresorptive medications, there are limited data on the use of anabolic treatments in LTx recipients. We present clinical, biochemical and bone mineral density data for 3 patients with severe osteoporosis treated with teriparatide 20 micrograms daily for 18 months post-LTx. Prednisone doses ranged between 5 and 10 mg daily throughout the treatment period. All patients had previously received zoledronate (last dose 12-24 months prior to teriparatide). Bone turnover was monitored repeatedly during treatment in one patient. Following completion of teriparatide, all patients received consolidation treatment with 4 mg zoledronate. Bone density was measured prior and within 6 to 12 months after completion of teriparatide. All 3 patients experienced an increase in bone density at the lumbar spine (median +12%; range, 2%-14%) and total proximal femur (median +8%, range, 8%-10%). No adverse effects were observed. Given that severe osteoporosis is highly prevalent in LTx patients, teriparatide should be further studied as a treatment in this clinical setting. Our cases suggest it is safe and effective.

Post-Transplant Bone Disease in Kidney Transplant Recipients: Diagnosis and Management

Kidney transplantation is the preferred gold standard modality of treatment for kidney failure. Bone disease after kidney transplantation is highly prevalent in patients living with a kidney transplant and is associated with high rates of hip fractures. Fractures are associated with increased healthcare costs, morbidity and mortality. Post-transplant bone disease (PTBD) includes renal osteodystrophy, osteoporosis, osteonecrosis and bone fractures. PTBD is complex as it encompasses pre-existing chronic kidney disease-mineral bone disease and compounding factors after transplantation, including the use of immunosuppression and the development of de novo bone disease. After transplantation, the persistence of secondary and tertiary hyperparathyroidism, renal osteodystrophy, relative vitamin D deficiency and high levels of fibroblast growth factor-23 contribute to post-transplant bone disease. Risk assessment includes identifying both general risk factors and kidney-specific risk factors. Diagnosis is complex as the gold standard bone biopsy with double-tetracycline labelling to diagnose the PTBD subtype is not always readily available. Therefore, alternative diagnostic tools may be used to aid its diagnosis. Both non-pharmacological and pharmacological therapy can be employed to treat PTBD. In this review, we will discuss pathophysiology, risk assessment, diagnosis and management strategies to manage PTBD after kidney transplantation.

New Human Leukocyte Antigen (HLA) Antibody Formation and Creatinine Elevation With Abaloparatide in Kidney Transplant Recipient

A 39-year-old female with a history of kidney transplant presented to the endocrinology clinic for osteoporosis evaluation after sustaining an ankle fracture from a fall. Her kidney transplant regimen (mycophenolate mofetil 360 mg twice a day, tacrolimus 0.5 mg every morning and 0.5-1 mg every evening, prednisone 5 mg/day) and baseline creatinine (1.0-1.2 mg/dL) had been stable for several years. After an appropriate secondary workup, she was started on abaloparatide 80 μg subcutaneous daily injections for osteoporosis. She had a good initial biochemical response to therapy. However, 5 months after abaloparatide initiation she was found to have a new elevation in serum creatinine (1.17 to 1.69 mg/dL) despite stable serum tacrolimus trough levels, and two new human leukocyte antigen (HLA) antibodies (anti-HLA antibodies detected to Cw7 and DP28). Abaloparatide was stopped due to concern for immunogenicity. There was no evidence of rejection on kidney biopsy and she was restabilized on her transplant regimen with a new baseline creatinine of 1.3-1.6 mg/dL. The patient was subsequently started on teriparatide 20 μg daily subcutaneous injections for 2 years with good biochemical response, significant improvement in bone mineral density, and stable transplant regimen without additional signs of immunogenicity or rejection. This is the first case report to raise concern about immunogenicity with abaloparatide in solid organ transplant recipients. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Efficacy and safety of medications for osteoporosis in kidney transplant recipients or patients with chronic kidney disease: A meta-analysis

This study conducted a meta-analysis to analyze the efficacy and safety of osteoporosis medications in kidney transplant recipients and patients with chronic kidney disease (CKD). PubMed, Embase, the Cochrane Central Register of Controlled Trials were searched from the date of their inception through October 21, 2022. We performed a meta-analysis of the efficacy and safety of osteoporosis medications in adult patients with stage 3-5 CKD or kidney transplant recipients enrolled in randomized clinical trials (RCTs). We calculated the standard mean deviations with 95% confidence intervals (CI) for bone mineral density (BMD) and T scores after 6 and 12 months treatment, pooled odds ratio and 95% CI for fracture risk, and summarized adverse events. The inclusion criteria were met by 27 studies. Out of this, 19 studies were included for the meta-analysis. In stage 3-4 CKD patients, alendronate increased lumbar spine BMD. In patients at stage 5 CKD and undergoing hemodialysis, alendronate and raloxifene increased lumbar spine BMD. After 6 months, the BMD of kidney transplant recipients was seen to be significantly increased; however, there was no difference after 12 months, and the risk of fracture did not reduce. Thus, there is no evidence that these medications reduce the risk of fracture, and their effect on BMD and fracture remains unproven. These medications may increase the incidence of adverse events and their safety needs to be further evaluated. Therefore, we cannot draw a definitive conclusion about the efficacy and safety of osteoporosis medications in the above group of patients.

Bone Turnover Markers: Basic Biology to Clinical Applications

Bone turnover markers (BTMs) are used widely, in both research and clinical practice. In the last 20 years, much experience has been gained in measurement and interpretation of these markers, which include commonly used bone formation markers bone alkaline phosphatase, osteocalcin, and procollagen I N-propeptide; and commonly used resorption markers serum C-telopeptides of type I collagen, urinary N-telopeptides of type I collagen and tartrate resistant acid phosphatase type 5b. BTMs are usually measured by enzyme-linked immunosorbent assay or automated immunoassay. Sources contributing to BTM variability include uncontrollable components (e.g., age, gender, ethnicity) and controllable components, particularly relating to collection conditions (e.g., fasting/feeding state, and timing relative to circadian rhythms, menstrual cycling, and exercise). Pregnancy, season, drugs, and recent fracture(s) can also affect BTMs. BTMs correlate with other methods of assessing bone turnover, such as bone biopsies and radiotracer kinetics; and can usefully contribute to diagnosis and management of several diseases such as osteoporosis, osteomalacia, Paget's disease, fibrous dysplasia, hypophosphatasia, primary hyperparathyroidism, and chronic kidney disease-mineral bone disorder.

Management of osteoporosis in patients with chronic kidney disease

Patients with CKD have a 4-fivefold higher rate of fractures. The incidence of fractures increases with deterioration of kidney function. The process of skeletal changes in CKD patients is characterized by compromised bone strength because of deterioration of bone quantity and/or quality. The fractures lead to a deleterious effect on the quality of life and higher mortality in patients with CKD. The pathogenesis of bone loss and fracture is complex and multi-factorial. Renal osteodystrophy, uremic milieu, drugs, and systemic diseases that lead to renal failure all contribute to bone damage in CKD patients. There is no consensus on the optimal diagnostic method of compromised bone assessment in patients with CKD. Bone quantity and mass can be assessed by dual-energy x-ray absorptiometry (DXA) or quantitative computed tomography (QCT). Bone quality on the other side can be assessed by non-invasive methods such as trabecular bone score (TBS), high-resolution bone imaging methods, and invasive bone biopsy. Bone turnover markers can reflect bone remodeling, but some of them are retained by kidneys. Understanding the mechanism of bone loss is pivotal in preventing fracture in patients with CKD. Several non-pharmacological and therapeutic interventions have been reported to improve bone health. Controlling laboratory abnormalities of CKD-MBD is crucial. Anti-resorptive therapies are effective in improving BMD and reducing fracture risk, but there are uncertainties about safety and efficacy especially in advanced CKD patients. Accepting the prevalent of low bone turnover in patients with advanced CKD, the osteo-anabolics are possibly promising. Parathyroidectomy should be considered a last resort for intractable cases of renal hyperparathyroidism. There is a wide unacceptable gap in osteoporosis management in patients with CKD. This article is focusing on the updated management of CKD-MBD and osteoporosis in CKD patients. Chronic kidney disease deteriorates bone quality and quantity. The mechanism of bone loss mainly determines pharmacological treatment. DXA and QCT provide information about bone quantity, but assessing bone quality, by TBS, high-resolution bone imaging, invasive bone biopsy, and bone turnover markers, can guide us about the mechanism of bone loss.

Bone and Mineral Disorder in Renal Transplant Patients: Overview of Pathology, Clinical, and Therapeutic Aspects

Renal transplantation (RTx) allows us to obtain the resolution of the uremic status but is not frequently able to solve all the metabolic complications present during end-stage renal disease. Mineral and bone disorders (MBDs) are frequent since the early stages of chronic kidney disease (CKD) and strongly influence the morbidity and mortality of patients with CKD. Some mineral metabolism (MM) alterations can persist in patients with RTx (RTx-p), as well as in the presence of complete renal function recovery. In those patients, anomalies of calcium, phosphorus, parathormone, fibroblast growth factor 23, and vitamin D such as bone and vessels are frequent and related to both pre-RTx and post-RTx specific factors. Many treatments are present for the management of post-RTx MBD. Despite that, the guidelines that can give clear directives in MBD treatment of RTx-p are still missed. For the future, to obtain an ever-greater individualisation of therapy, an increase of the evidence, the specificity of international guidelines, and more uniform management of these anomalies worldwide should be expected. In this review, the major factors related to post-renal transplant MBD (post-RTx-MBD), the main mineral metabolism biochemical anomalies, and the principal treatment for post-RTx MBD will be reported.

Bone and Mineral Disease in Kidney Transplant Recipients

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.

Bone Mineral Disease After Kidney Transplantation

Chronic kidney disease-mineral bone disorder (CKD-MBD) after kidney transplantation is a mix of pre-existing disorders and new alterations. The final consequences are reflected fundamentally as abnormal mineral metabolism (hypercalcemia, hypophosphatemia) and bone alterations [high or low bone turnover disease (as fibrous osteitis or adynamic bone disease), an eventual compromise of bone mineralization, decrease bone mineral density and bone fractures]. The major cause of post-transplantation hypercalcemia is the persistence of severe secondary hyperparathyroidism, and treatment options include calcimimetics or parathyroidectomy. On turn, hypophosphatemia is caused by both the persistence of high blood levels of PTH and/or high blood levels of FGF23, with its correction being very difficult to achieve. The most frequent bone morphology alteration is low bone turnover disease, while high-turnover osteopathy decreases in frequency after transplantation. Although the pathogenic mechanisms of these abnormalities have not been fully clarified, the available evidence suggests that there are a number of factors that play a very important role, such as immunosuppressive treatment, persistently high levels of PTH, vitamin D deficiency and hypophosphatemia. Fracture risk is four-fold higher in transplanted patients compared to general population. The most relevant risk factors for fracture in the kidney transplant population are diabetes mellitus, female sex, advanced age (especially > 65 years), dialysis vintage, high PTH levels and low phosphate levels, osteoporosis, pre-transplant stress fracture and high doses or prolonged steroids therapy. Treatment alternatives for CKD-MBD after transplantation include minimization of corticosteroids, use of calcium and vitamin D supplements, antiresorptives (bisphosphonates or Denosumab) and osteoformers (synthetic parathyroid hormone). As both mineral metabolism and bone disorders lead to increased morbidity and mortality, the presence of these changes after transplantation has to be prevented (if possible), minimized, diagnosed, and treated as soon as possible.

Mineral Bone Disorders in Kidney Transplantation

Bone disease after kidney transplantation is associated with an increased risk of fractures, morbidity, and mortality. Its pathophysiology is complex, involving multiple contributors including pretransplant bone disease, immunosuppressive medications, and changes in the parathyroid-bone-kidney axis. Risk scores, bone turnover markers, and noninvasive imaging modalities are only able to partially predict the fracture risk in kidney transplant recipients. The optimal management of bone disease after kidney transplantation has not yet been established, with only a limited number of randomized clinical trials evaluating the efficacy of treatment regimens in kidney transplant recipients. This review focuses on the pathophysiology, evaluation, prevention, and treatment of post-kidney transplant mineral and bone disease as guided by recent evidence.

Osteoporosis in Patients with Chronic Kidney Diseases: A Systemic Review

Chronic kidney disease (CKD) is associated with the development of mineral bone disorder (MBD), osteoporosis, and fragility fractures. Among CKD patients, adynamic bone disease or low bone turnover is the most common type of renal osteodystrophy. The consequences of CKD-MBD include increased fracture risk, greater morbidity, and mortality. Thus, the goal is to prevent the occurrences of fractures by means of alleviating CKD-induced MBD and treating subsequent osteoporosis. Changes in mineral and humoral metabolism as well as bone structure develop early in the course of CKD. CKD-MBD includes abnormalities of calcium, phosphorus, PTH, and/or vitamin D; abnormalities in bone turnover, mineralization, volume, linear growth, or strength; and/or vascular or other soft tissue calcification. In patients with CKD-MBD, using either DXA or FRAX to screen fracture risk should be considered. Biomarkers such as bALP and iPTH may assist to assess bone turnover. Before initiating an antiresorptive or anabolic agent to treat osteoporosis in CKD patients, lifestyle modifications, such as exercise, calcium, and vitamin D supplementation, smoking cessation, and avoidance of excessive alcohol intake are important. Managing hyperphosphatemia and SHPT are also crucial. Understanding the complex pathogenesis of CKD-MBD is crucial in improving one's short- and long-term outcomes. Treatment strategies for CKD-associated osteoporosis should be patient-centered to determine the type of renal osteodystrophy. This review focuses on the mechanism, evaluation and management of patients with CKD-MBD. However, further studies are needed to explore more details regarding the underlying pathophysiology and to assess the safety and efficacy of agents for treating CKD-MBD.

Risk Factors and Management of Osteoporosis Post-Transplant

Bone and mineral disorders are common after organ transplantation. Osteoporosis post transplantation is associated with increased morbidity and mortality. Pathogenesis of bone disorders in this particular sub set of the population is complicated by multiple co-existing factors like preexisting bone disease, Vitamin D deficiency and parathyroid dysfunction. Risk factors include post-transplant immobilization, steroid usage, diabetes mellitus, low body mass index, older age, female sex, smoking, alcohol consumption and a sedentary lifestyle. Immunosuppressive medications post-transplant have a negative impact on outcomes, and further aggravate osteoporotic risk. Management is complex and challenging due to the sub-optimal sensitivity and specificity of non-invasive diagnostic tests, and the underutilization of bone biopsy. In this review, we summarize the prevalence, pathophysiology, diagnostic tests and management of osteoporosis in solid organ and hematopoietic stem cell transplant recipients.

Annatto-Derived Tocotrienol Promotes Mineralization of MC3T3-E1 Cells by Enhancing BMP-2 Protein Expression via Inhibiting RhoA Activation and HMG-CoA Reductase Gene Expression

PURPOSE

Annatto-derived tocotrienol (AnTT) has been shown to improve bone formation in animal models of osteoporosis and promote differentiation of pre-osteoblastic cells. However, the mechanism of action of AnTT in achieving these effects is unclear. This study aims to investigate the mechanism of action of AnTT on MC3T3-E1 pre-osteoblasts via the mevalonate pathway.

METHODS

Murine pre-osteoblastic cells, MC3T3-E1, were cultured with the density of 1 × 104 cells/mL and treated with 4 concentrations of AnTT (0.001-1 µg/mL). Expression of HMG-CoA reductase (HMGR) gene was carried out using qPCR after treatment with AnTT for 21 days. RhoA activation and bone morphogenetic protein-2 (BMP-2) were measured using immunoassay after 9 and 15 days of AnTT treatment. Lovastatin was used as the positive control. Mineralized nodules were detected using Von Kossa staining after 21 days of AnTT treatment.

RESULTS

The results showed that HMGR was up-regulated in the lovastatin group on day 9 and 21 compared to the control. Lovastatin also inhibited RhoA activation (day 9 and 15) and increased BMP-2 protein (day 15). On the other hand, AnTT at 0.001 μg/mL (day 3) and 0.1 μg/mL (day 21) significantly down-regulated HMGR gene expression compared to the control. On day 21, HMGR gene expression was significantly reduced in all groups compared to day 15. AnTT at 0.1 μg/mL significantly decreased RhoA activation on day 9 compared to the control. AnTT at 1 μg/mL significantly increased BMP-2 protein on day 15 compared to the control (P<0.05). Mineralized calcium nodules were more abundant in AnTT treated groups compared to the control on day 21.

CONCLUSION

AnTT suppresses the mevalonate pathway by downregulating HMGR gene expression and inhibiting RhoA activation, leading to increased BMP-2 protein in MC3T3-E1 cells. This explains the stimulating effects of AnTT on osteoblast mineralization.

Interventions for preventing bone disease in kidney transplant recipients

BACKGROUND

People who have chronic kidney disease (CKD) have important changes to bone structure, strength, and metabolism. Children experience bone deformity, pain, and delayed or impaired growth. Adults experience limb and vertebral fractures, avascular necrosis, and pain. The fracture risk after kidney transplantation is four times that of the general population and is related to Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) occurring with end-stage kidney failure, steroid-induced bone loss, and persistent hyperparathyroidism after transplantation. Fractures may reduce quality of life and lead to being unable to work or contribute to community roles and responsibilities. Earlier versions of this review have found low certainty evidence for effects of treatment. This is an update of a review first published in 2005 and updated in 2007.

OBJECTIVES

This review update evaluates the benefits and harms of interventions for preventing bone disease following kidney transplantation.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 16 May 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

RCTs and quasi-RCTs evaluating treatments for bone disease among kidney transplant recipients of any age were eligible.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial risks of bias and extracted data. Statistical analyses were performed using random effects meta-analysis. The risk estimates were expressed as a risk ratio (RR) for dichotomous variables and mean difference (MD) for continuous outcomes together with the corresponding 95% confidence interval (CI). The primary efficacy outcome was bone fracture. The primary safety outcome was acute graft rejection. Secondary outcomes included death (all cause and cardiovascular), myocardial infarction, stroke, musculoskeletal disorders (e.g. skeletal deformity, bone pain), graft loss, nausea, hyper- or hypocalcaemia, kidney function, serum parathyroid hormone (PTH), and bone mineral density (BMD).

MAIN RESULTS

In this 2019 update, 65 studies (involving 3598 participants) were eligible; 45 studies contributed data to our meta-analyses (2698 participants). Treatments included bisphosphonates, vitamin D compounds, teriparatide, denosumab, cinacalcet, parathyroidectomy, and calcitonin. Median duration of follow-up was 12 months. Forty-three studies evaluated bone density or bone-related biomarkers, with more recent studies evaluating proteinuria and hyperparathyroidism. Bisphosphonate therapy was usually commenced in the perioperative transplantation period (within 3 weeks) and regardless of BMD. Risks of bias were generally high or unclear leading to lower certainty in the results. A single study reported outcomes among 60 children and adolescents. Studies were not designed to measure treatment effects on fracture, death or cardiovascular outcomes, or graft loss.Compared to placebo, bisphosphonate therapy administered over 12 months in transplant recipients may prevent fracture (RR 0.62, 95% CI 0.38 to 1.01; low certainty evidence) although the 95% CI included the possibility that bisphosphonate therapy might make little or no difference. Fracture events were principally vertebral fractures identified during routine radiographic surveillance. It was uncertain whether any other drug class decreased fracture (low or very low certainty evidence). It was uncertain whether interventions for bone disease in kidney transplantation reduce all-cause or cardiovascular death, myocardial infarction or stroke, or graft loss in very low certainty evidence. Bisphosphonate therapy may decrease acute graft rejection (RR 0.70, 95% CI 0.55 to 0.89; low certainty evidence), while it is uncertain whether any other treatment impacts graft rejection (very low certainty evidence). Bisphosphonate therapy may reduce bone pain (RR 0.20, 95% CI 0.04 to 0.93; very low certainty evidence), while it was very uncertain whether bisphosphonates prevent spinal deformity or avascular bone necrosis (very low certainty evidence). Bisphosphonates may increase to risk of hypocalcaemia (RR 5.59, 95% CI 1.00 to 31.06; low certainty evidence). It was uncertain whether vitamin D compounds had any effect on skeletal, cardiovascular, death, or transplant function outcomes (very low certainty or absence of evidence). Evidence for the benefits and harms of all other treatments was of very low certainty. Evidence for children and young adolescents was sparse.

AUTHORS' CONCLUSIONS

Bisphosphonate therapy may reduce fracture and bone pain after kidney transplantation, however low certainty in the evidence indicates it is possible that treatment may make little or no difference. It is uncertain whether bisphosphonate therapy or other bone treatments prevent other skeletal complications after kidney transplantation, including spinal deformity or avascular bone necrosis. The effects of bone treatment for children and adolescents after kidney transplantation are very uncertain.

Bone disease following solid organ transplantation: A narrative review and recommendations for management from The European Calcified Tissue Society

INTRODUCTION

Solid organ transplantation is an established therapy for end-stage organ failure. Both pre-transplantation bone disease and immunosuppressive regimens result in rapid bone loss and increased fracture rates.

METHODS

The European Calcified Tissue Society (ECTS) formed a working group to perform a systematic review of existing literature on the consequences of end-stage kidney, liver, heart, and lung disease on bone health. Moreover, we assessed the characteristics of post-transplant bone disease and the skeletal effects of immunosuppressive agents and aimed to provide recommendations for the prevention and treatment of transplantation-related osteoporosis.

RESULTS

Characteristics of bone disease may differ depending on the organ that fails, but patients awaiting solid organ transplantation frequently depict a wide spectrum of bone and mineral abnormalities. Common features are a decreased bone mass and impaired bone strength with consequent high fracture risk, all of which are aggravated in the early post-transplantation period.

CONCLUSION

Both the underlying disease leading to end-stage organ failure and the immunosuppression regimens implemented after successful organ transplantation have detrimental effects on bone mass, quality and strength. Given existing ample data confirming the high frequency of bone disease in patients awaiting solid organ transplantation, we recommend that all transplant candidates should be assessed for osteoporosis and fracture risk and, if indicated, treated before and after transplantation. Since bone loss in the early post-transplantation period occurs in virtually all solid organ recipients and is associated with glucocorticoid administration, the goal should be to use the lowest possible dose and to taper and withdraw glucocorticoids as early as possible.

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.

Mineral and Bone Disease in Kidney Transplant Recipients

PURPOSE OF REVIEW

Despite metabolic improvements following kidney transplantation, transplant recipients still often suffer from complex mineral and bone disease after transplantation.

RECENT FINDINGS

The pathophysiology of post-transplant disease is unique, secondary to underlying pre-transplant mineral and bone disease, immunosuppression, and changing kidney function. Changes in modern immunosuppression regimens continue to alter the clinical picture. Modern management includes reducing cumulative steroid exposure and correcting the biochemical abnormalities in mineral metabolism. While bone mineral density screening appears to help predict fracture risk and anti-osteoporotic therapy appears to have a positive effect on bone mineral density, more data regarding specific treatment is necessary. Patients with mineral and bone disease after kidney transplantation require special care in order to properly manage and mitigate their mineral and bone disease. Recent changes in clinical management of transplant patients may also be changing the implications on patients' mineral and bone disease.

Updates in CKD-Associated Osteoporosis

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is associated with bone loss and fractures. The purpose of this review is to provide clinicians with an overview of the underlying pathogenesis of CKD-associated osteoporosis, and a summary of the current diagnostic and therapeutic approaches to this disease.

RECENT FINDINGS

In 2017, the Kidney Disease Improving Global Outcomes Committee on Bone Quality updated their guidelines to include screening for osteoporosis and fracture risk by dual energy X-ray absorptiometry in patients with CKD. Once a diagnosis of osteoporosis and/or fracture risk is established, it is not clear how nephrologists should manage their patients. Patients with CKD should be screened for CKD-associated osteoporosis and considered for strategies that prevent bone loss and fractures. Assessment of bone turnover via imaging, biochemical testing, or bone biopsy can help guide the choice of therapy. Randomized controlled trials are needed to assess safety and efficacy of treatments to prevent bone loss and fractures.

Mineral and Bone Disorders After Kidney Transplantation

The risk of mineral and bone disorders among patients with chronic kidney disease is substantially elevated, owing largely to alterations in calcium, phosphorus, vitamin D, parathyroid hormone, and fibroblast growth factor 23. The interwoven relationship among these minerals and hormones results in maladaptive responses that are differentially affected by the process of kidney transplantation. Interpretation of conventional labs, imaging, and other fracture risk assessment tools are not standardized in the post-transplant setting. Post-transplant bone disease is not uniformly improved and considerable variation exists in monitoring and treatment practices. A spectrum of abnormalities such as hypophosphatemia, hypercalcemia, hyperparathyroidism, osteomalacia, osteopenia, and osteoporosis are commonly encountered in the post-transplant period. Thus, reducing fracture risk and other bone-related complications requires recognition of these abnormalities along with the risk incurred by concomitant immunosuppression use. As kidney transplant recipients continue to age, the drivers of bone disease vary throughout the post-transplant period among persistent hyperparathyroidism, de novo hyperparathyroidism, and osteoporosis. The use of anti-resorptive therapies require understanding of different options and the clinical scenarios that warrant their use. With limited studies underscoring clinical events such as fractures, expert understanding of MBD physiology, and surrogate marker interpretation is needed to determine ideal and individualized therapy.

Annatto-derived tocotrienol stimulates osteogenic activity in preosteoblastic MC3T3-E1 cells: a temporal sequential study

PURPOSE

Annatto-derived tocotrienol (AnTT) has been shown to improve bone formation in animal models of osteoporosis. However, detailed studies of the effects of AnTT on preosteoblastic cells were limited. This study was conducted to investigate the osteogenic effect of AnTT on preosteoblast MC3T3-E1 cells in a time-dependent manner.

MATERIALS AND METHODS

Murine MC3T3-E1 preosteoblastic cells were cultured in the different concentrations of AnTT (0.001-1 µg/mL) up to 24 days. Expression of osteoblastic differentiation markers was measured by qPCR (osterix [OSX], collagen 1 alpha 1 [COL1α1], alkaline phosphatase [ALP], and osteocalcin [OCN]) and by fluorometric assay for ALP activity. Detection of collagen and mineralized nodules was done via Direct Red staining and Alizarin Red staining, respectively.

RESULTS

The results showed that osteoblastic differentiation-related genes, such as OSX, COL1α1, ALP, and OCN, were significantly increased in the AnTT-treated groups compared to the vehicle group in a time-dependent manner (P<0.05). Type 1 collagen level was increased from day 3 to day 15 in the AnTT-treated groups, while ALP activity was increased from day 9 to day 21 in the AnTT-treated groups (P<0.05). Enhanced mineralization was observed in the AnTT-treated groups via increasing Alizarin Red staining from day 3 to day 21 (P<0.05).

CONCLUSION

Our results suggest that AnTT enhances the osteogenic activity by promoting the bone formation-related genes and proteins in a temporal and sequential manner.

Is there a practical role for bone biopsy in chronic kidney disease?

Bone biopsy is currently the only means to accurately assess renal osteodystrophy and responses to therapeutic interventions. With sedation, the technique is relatively painless, and complications are uncommon. Bone biopsy should be considered when the aetiology of symptoms or biochemical abnormalities is in question, and results may lead to changes in therapy. Although it remains prudent to use antiresorptive drugs cautiously in patients with chronic kidney disease (CKD) stages 3a-4 and low bone mineral density, bone biopsy may not be warranted before commencing therapy in these patients. Histomorphometric indices adopted for bone biopsy assessment are turnover (T), mineralisation (M) and volume (V). Often, only measurements of trabecular bone are reported; however, marked cortical changes are common in CKD and may be critical to bone structure and integrity. MicroCT of bone biopsies can rapidly assess static parameters and provides information on the cortical and trabecular compartments that may influence management. Limitations of bone biopsy include the time required for pre-biopsy tetracycline labelling and sample processing, and a paucity of facilities to process and report samples. Patients with CKD may not respond predictably to treatments, and because the biopsy sample is illustrative of activity at only one skeletal site and one point in time, assessment of real-time laboratory trends is always required. Optimally, we need a non-invasive 'virtual bone biopsy' that provides information for initiating and monitoring therapy. However, bone biopsy is the current standard by which the accuracy of investigational imaging techniques, hormonal values and biochemical turnover markers are judged.

Osteoporosis following heart transplantation and immunosuppressive therapy

Heart transplantation (HT) remains the ultimate final therapy for patients with end-stage heart failure, who despite optimal medical and surgical treatments exhibit severe symptoms. To prevent rejection of the transplanted organ, HT patients require life-long immunosuppressive therapy. The goal of the immunosuppression is to minimise the risk of immune-mediated graft rejection, while avoiding clinical side-effects. Current immunosuppressive agents have yielded good survival outcome, however, complications of the immunosuppressive therapy, such as impaired bone strength and increased fracture risk, are common among HT patients rendering increased morbidity and mortality rates. The main aim of the present review was to summarise current knowledge on bone strength impairment after HT and concomitant immunosuppressive therapy.

Long-term outcomes and management of lung transplant recipients

Lung transplantation is an established treatment for patients with end-stage lung disease. Improvements in immunosuppression and therapeutic management of infections have resulted in improved long-term survival and a decline in allograft rejection. Allograft rejection continues to be a serious complication following lung transplantation, thereby leading to acute graft failure and, subsequently, chronic lung allograft dysfunction (CLAD). Bronchiolitis obliterans syndrome (BOS), the most common phenotype of CLAD, is the leading cause of late mortality and morbidity in lung recipients, with 50% having developed BOS within 5 years of lung transplantation. Infections in lung transplant recipients are also a significant complication and represent the most common cause of death within the first year. The success of lung transplantation depends on careful management of immunosuppressive regimens to reduce the rate of rejection, while monitoring recipients for infections and complications to help identify problems early. The long-term outcomes and management of lung transplant recipients are critically based on modulating natural immune response of the recipient to prevent acute and chronic rejection. Understanding the immune mechanisms and temporal correlation of acute and chronic rejection is thus critical in the long-term management of lung recipients.

Comprehensive Care of the Lung Transplant Patient

Lung transplantation has evolved into a life-saving treatment with improved quality of life for patients with end-stage respiratory failure unresponsive to other medical or surgical interventions. With improving survival rates, the number of lung transplant recipients with preexisting and posttransplant comorbidities that require attention continues to increase. A partnership between transplant and nontransplant care providers is necessary to deliver comprehensive and optimal care for transplant candidates and recipients. The goals of this partnership include timely referral and assistance with transplant evaluation, optimization of comorbidities and preparation for transplantation, management of common posttransplant medical comorbidities, immunization, screening for malignancy, and counseling for a healthy lifestyle to maximize the likelihood of a good outcome. We aim to provide an outline of the main aspects of the care of candidates for and recipients of lung transplants for nontransplant physicians and other care providers.

Bone Disease after Kidney Transplantation

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.

Metabolic Bone Disease in the Post-transplant Population: Preventative and Therapeutic Measures

Post-transplant bone disease contributes significantly to patients' morbidity and mortality after transplantation and has an impact on their quality of life. This article discusses the major contributors to mechanisms causing bone loss, highlighting the role of preexisting disease in both kidney and liver failure and contributions from glucocorticoids and calcineurin inhibitors. Suggested monitoring and investigations are reviewed as well as treatment as far as the current literature supports, emphasizing the difference between kidney and liver recipients.

Osteoporosis in the adult solid organ transplant population: underlying mechanisms and available treatment options

The prevention and treatment of osteoporosis is an increasingly important topic in the solid organ transplant (SOT) population. Compared to the general population, these patients are at an elevated risk of developing osteoporosis due to progressive disease, lifelong immunosuppressant therapy, and malnutrition. As patients live longer after transplant, chronic disease management is increasingly more important. Supplementation with calcium and vitamin D is often necessary in the SOT population due to a high incidence of vitamin D deficiency. Bisphosphonate therapy is most commonly used for prevention and treatment of osteoporosis, but therapy can be limited by renal dysfunction which is common in transplant recipients. Alternative agents such as teriparatide and calcitonin have not been shown to provide a significant impact on the rate of fractures in this population. Additionally, denosumab may be a promising treatment option due to its novel mechanism of action, and is currently being studied in renal transplant patients. Timely initiation of supplementation and treatment, and minimizing glucocorticoid exposure prior to and after transplantation will aid in the prevention and proper management of osteoporosis in these patients.

Bone disease in post-transplant patients

PURPOSE OF REVIEW

Mineral and bone disorders are common problems in organ transplant recipients. Successful transplantation solves many aspects of abnormal mineral and bone metabolism, but the degree of improvement is frequently incomplete. Posttransplant bone disease can affect long-term outcomes as well as increase the likelihood of fracture. In this article, we reviewed the major posttransplant bone diseases and recent advances in treatment strategies.

RECENT FINDINGS

Pretransplant bone disease and immunosuppressants are important risk factors for posttransplant bone disease. Corticosteroid withdrawal may result in minimal or no protection against fractures, with increased risk for acute rejection. Vitamin D analogue and bisphosphonate are frequently used to prevent and treat posttransplant osteoporosis. Posttransplant hyperparathyroidism increases the risk for all-cause mortality and graft loss, but not major cardiovascular events. Cinacalcet was well tolerated and effectively controlled hypercalcemic hyperparathyroidism; however, it did not improve bone mineral density and discontinuation led to parathyroid hormone rebound. Six-month paricalcitol supplementation reduced parathyroid hormone levels and attenuated bone remodeling and mineral loss in case of posttransplant hyperparathyroidism.

SUMMARY

Posttransplant bone diseases present in various forms, including osteoporosis, hyperparathyroidism, adynamic bone disease, and osteonecrosis. Prophylactic and therapeutic approaches to both pretransplant and posttransplant periods should be considered.

Fifty shades of gray: Bone disease in renal transplantation

Kidney transplantation is the renal replacement therapy of choice for patients with end stage renal disease. Advances in technology, surgical techniques and pharmacotherapy have improved renal allograft survival. Increasingly, we are seeing long term side effects related to renal transplantation, bone disease being a major one amongst them. Renal transplant patients have a higher risk of fragility fractures even when compared to those who remain on dialysis. This is likely to be related to pre-existing underlying bone disease and the emergence of new metabolic bone problems post-transplant. Conditions such as persistent hyperparathyroidism and the use of certain immunosuppressive agents have a deleterious effect on the post renal transplant bone.

Remarkable advances in the field of metabolic bone research have been made in the last decade and newer imaging techniques, biomarkers and therapeutic options are now available for osteoporosis in the general population. Interest is being focused on attempting to extrapolate these new discoveries to the management of bone disease post renal transplant. This review will briefly describe the metabolic bone changes that occur after transplantation and will provide an update on the currently available investigative options and therapeutic strategies for the management of post renal transplant bone disease.

Current Status of Research on Osteoporosis after Solid Organ Transplantation: Pathogenesis and Management

Improved survival following organ transplantation has brought to the forefront some long-term complications, among which osteoporosis and associated fractures are the major ones that adversely affect the quality of life in recipients. The pathogenesis of osteoporosis in transplant recipients is complex and multifactorial which may be related to increased bone resorption, decreased bone formation, or both. Studies have shown that the preexisting underlying metabolic bone disorders and the use of immunosuppressive agents are the major risk factors for osteoporosis and fractures after organ transplantation. And rapid bone loss usually occurs in the first 6–12 months with a significant increase in fracture risk. This paper will provide an updated review on the possible pathogenesis of posttransplant osteoporosis and fractures, the natural history, and the current prevention and treatment strategies concerning different types of organ transplantation.

How to predict and treat increased fracture risk in chronic kidney disease

Men and women with chronic kidney disease (CKD) are at an increased risk of fracture, and this risk increases as kidney function deteriorates. Fractures are associated with morbidity, mortality and economic costs. Despite this, there is a paucity of data regarding how to evaluate risk for fractures in CKD and how to treat high-risk patients. Evidence suggests that bone mineral density (BMD) as assessed by dual-energy X-ray absorptiometry (DXA) is associated with fractures and can also predict future fractures in predialysis (stages 1-3) patients with CKD. In the absence of considerable abnormalities in markers of mineral metabolism, treatment with antiresorptive agents in men and women with early CKD at high fracture risk may be appropriate. Of note, recent data suggest that low BMD as measured by DXA can also predict fractures in patients with more advanced CKD (stages 4, 5 and 5D). However, treatment in patients with advanced CKD requires bone biopsy, the gold standard to assess bone turnover, prior to treatment. Further research, focusing on noninvasive methods to assess fracture risk and bone turnover, together with randomized controlled trials of treatments to reduce fractures in patients at all stages of CKD, is required.

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.

Bone disease after transplantation: osteoporosis and fractures risk

Organ transplantation is the gold standard therapy for several end-stage diseases. Bone loss is a common complication that occurs in transplant recipients. Osteoporosis and fragility fractures are serious complication, mainly in the first year post transplantation. Many factors contribute to the pathogenesis of bone disease following organ transplantation. This review address the mechanisms of bone loss including the contribution of the immunosuppressive agents as well as the specific features to bone loss after kidney, lung, liver, cardiac and bone marrow transplantation. Prevention and management of bone loss in the transplant recipient should be included in their post transplant follow-up in order to prevent fractures.

Bone and mineral disorders after kidney transplantation: therapeutic strategies

Mineral and bone diseases (MBD) are common in patients with chronic kidney disease who undergo kidney transplantation. The incidence, types and severity of MBD vary according to the duration of chronic kidney disease, presence of comorbid conditions and intake of certain medications. Moreover, multiple types of pathology may be responsible for MBD. After successful reversal of uremia by kidney transplantation, many bone and mineral disorders improve, while immunosuppression, other medications, and new and existing comorbidities may result in new or worsening MBD. Chronic kidney disease is also common after kidney transplantation and may impact bone and mineral disease. In this article, we reviewed the prevalence, pathophysiology, and impact of MBD on post-transplant outcomes. We also discussed the diagnostic approach; immunosuppression management and potential treatment of MBD in kidney transplant recipients.

Recovery versus persistence of disordered mineral metabolism in kidney transplant recipients

In patients with end-stage renal disease, successful renal transplantation improves the quality of life and increases survival, as compared with long-term dialysis treatment. Although it long has been believed that successful kidney transplantation to a large extent solves the problem of chronic kidney disease-mineral and bone disorders (CKD-MBD), increasing evidence indicates that it only changes the phenotype of CKD-MBD. Posttransplant CKD-MBD reflects the effects of immunosuppression, previous CKD-MBD persisting after transplantation, and de novo CKD-MBD. A major and often-underestimated problem after successful renal transplantation is persistent hyperparathyroidism. Besides contributing to posttransplant hypercalcemia and hypophosphatemia, persistent hyperparathyroidism may be involved in the pathogenesis of allograft dysfunction (nephrocalcinosis), progression of vascular calcification, and bone disease (uncoupling of bone formation and bone resorption and bone mineral density loss) in renal transplant recipients. Similar to nontransplanted patients, CKD-MBD has a detrimental impact on (cardiovascular) mortality and morbidity. Additional studies urgently are needed to get more insights into the pathophysiology of posttransplant CKD-MBD. These new insights will allow for a more targeted and causal therapeutic approach.

Quantifying mineralization using bone mineral density distribution in the mandible

BACKGROUND

Micro-computed tomography is an efficient method for quantifying the density and mineralization of mandibular microarchitecture. Conventional radiomorphometrics such as bone and tissue mineral density are useful in determining the average overall mineral content of a scanned specimen; however, relying solely on these metrics has limitations. Using bone mineral density distribution (BMDD), the complex array of mineralization densities within a bone sample can be portrayed. This information is particularly useful as a computational feature reflective of the rate of bone turnover. We demonstrate the utility of BMDD analyses in the rat mandible and generate a platform for further exploration of mandibular pathology and treatment.

METHODS

Male Sprague-Dawley rats (n = 8) underwent micro-computed tomography, and histogram data were generated from a selected volume of interest. A standard curve was derived for each animal, and reference criteria were defined. An average histogram was produced for the group, and descriptive analyses including the means and SDs are reported for each of the normative metrics.

RESULTS

M(peak) (3444 Hounsfield units [SD, 138]) and M(width) (2221 Hounsfield units [SD, 628]) are 2 metrics demonstrating reproducible parameters of BMDD with minimal variance. A total of 8 valuable metrics quantifying biologically significant events concerning mineralization are reported.

CONCLUSIONS

We quantify the vast wealth of information depicted in the complete spectrum of mineralization established by the BMDD analysis. We demonstrate its potential in delivering mineralization data that encompass and enhance conventional reporting of radiomorphometrics. Moreover, we explore its role and translational potential in craniofacial experimentation.

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.

Bone disease in organ transplant patients: pathogenesis and management

Bone disease is common in recipients of kidney, heart, lung, liver, and bone marrow transplants, and causes debilitating complications, such as osteoporosis, osteonecrosis, bone pain, and fractures. The frequency of fractures ranges from 6% to 45% for kidney transplant recipients to 22% to 42% for heart, lung, and liver transplant recipients. Bone disease in transplant patients is the sum of complex mechanisms that involve both preexisting bone disease before transplant and post-transplant bone loss due to the effects of immunosuppressive medications. Evaluation of bone disease should preferably start before the transplant or in the early post-transplant period and include assessment of bone mineral density and other metabolic factors that influence bone health. This requires close coordination between the primary care physician and transplant team. Patients should be stratified based on their fracture risk. Prevention and treatment include risk factor reduction, antiresorptive medications, such as bisphosphonates and calcitonin, calcitriol, and/or gonadal hormone replacement. A steroid-avoidance protocol may be considered.

Metabolic bone diseases in kidney transplant recipients

Metabolic bone disease after kidney transplantation has a complex pathophysiology and heterogeneous histology. Pre-existing renal osteodystrophy may not resolve completely, but continue or evolve into a different osteodystrophy. Rapid bone loss immediately after transplant can persist, at a lower rate, for years to come. These greatly increase the risk of bone fracture and vertebral collapse. Each patient may have multiple risk factors of bone loss, such as steroids usage, hypogonadism, persistent hyperparathyroidism (HPT), poor allograft function, metabolic acidosis, hypophosphatemia, vitamin D deficiency, aging, immobility and chronic disease. Clinical management requires a comprehensive approach to address the underlying and ongoing disease processes. Successful prevention of bone loss has been shown with vitamin D, bisphosphonates, calcitonin as well as treatment of hypogonadism and HPT. Novel approach to restore the normal bone remodeling and improve the bone quality may be needed in order to effectively decrease bone fracture rate in kidney transplant recipients.

Management of mineral and bone disorder after kidney transplantation

PURPOSE OF REVIEW

Mineral and bone disorders (MBDs), inherent complications of moderate and advanced chronic kidney disease, occur frequently in kidney transplant recipients. However, much confusion exists about the clinical application of diagnostic tools and preventive or treatment strategies to correct bone loss or mineral disarrays in transplanted patients. We have reviewed the recent evidence about prevalence and consequences of MBD in kidney transplant recipients and examined diagnostic, preventive and therapeutic options to this end.

RECENT FINDINGS

Low turnover bone disease occurs more frequently after kidney transplantation according to bone biopsy studies. The risk of fracture is high, especially in the first several months after kidney transplantation. Alterations in minerals (calcium, phosphorus and magnesium) and biomarkers of bone metabolism (parathyroid hormone, alkaline phosphatase, vitamin D and FGF-23) are observed with varying impact on posttransplant outcomes. Calcineurin inhibitors are linked to osteoporosis, whereas steroid therapy may lead to both osteoporosis and varying degrees of osteonecrosis. Sirolimus and everolimus might have a bearing on osteoblast proliferation and differentiation or decreasing osteoclast-mediated bone resorption. Selected pharmacologic interventions for the treatment of MBD in transplant patients include steroid withdrawal, and the use of bisphosphonates, vitamin D derivatives, calcimimetics, teriparatide, calcitonin and denosumab.

SUMMARY

MBD following kidney transplantation is common and characterized by loss of bone volume and mineralization abnormalities, often leading to low turnover bone disease. Although there are no well established therapeutic approaches for management of MBD in renal transplant recipients, clinicians should continue individualizing therapy as needed.

Osteoporosis after transplantation

Transplantation is an established therapy for end-stage diseases of kidney, lung, liver, and heart among others. Osteoporosis and fragility fractures are serious complications of organ transplantation, particularly in the first post-transplant year. Many factors contribute to the pathogenesis of osteoporosis following organ transplantation. This review addresses the mechanisms of bone loss that occurs both in the early and late post-transplant periods, including the contribution of the immunosuppressive agents as well as the specific features to bone loss after kidney, lung, liver, cardiac, and bone marrow transplantation. Prevention and treatment for osteoporosis in the transplant recipient are also discussed.