Bone density in heart or lung transplant recipients--a longitudinal study

Bone Loss after Solid Organ Transplantation: A Review of Organ-Specific Considerations

This review article investigates solid organ transplantation-induced osteoporosis, a critical yet often overlooked issue, emphasizing its significance in post-transplant care. The initial sections provide a comprehensive understanding of the prevalence and multifactorial pathogenesis of transplantation osteoporosis, including factors such as deteriorating post-transplantation health, hormonal changes, and the impact of immunosuppressive medications. Furthermore, the review is dedicated to organ-specific considerations in transplantation osteoporosis, with separate analyses for kidney, liver, heart, and lung transplantations. Each section elucidates the unique challenges and management strategies pertinent to transplantation osteoporosis in relation to each organ type, highlighting the necessity of an organ-specific approach to fully understand the diverse manifestations and implications of transplantation osteoporosis. This review underscores the importance of this topic in transplant medicine, aiming to enhance awareness and knowledge among clinicians and researchers. By comprehensively examining transplantation osteoporosis, this study contributes to the development of improved management and care strategies, ultimately leading to improved patient outcomes in this vulnerable group. This detailed review serves as an essential resource for those involved in the complex multidisciplinary care of transplant recipients.

The Association between Objectively Measured Physical Activity and the Prevalence of Comorbidities in Lung Transplant Recipients

INTRODUCTION

Lung transplant recipients are often physically inactive and are at risk of developing comorbidities. We investigated whether objectively measured physical activity was associated with the prevalence of comorbidities.

METHODS

Physical activity (accelerometry) and the presence of cardiovascular disease, symptoms of depression and anxiety, diabetes, dyslipidaemia, hypertension, lower extremity artery disease, muscle weakness, obesity, and osteoporosis were assessed in 108 lung transplant recipients. Patients were divided into four groups based on daily step count.

RESULTS

A cohort of 108 patients (60 ± 7 years, 51% male, 20 ± 14 months since transplantation) was included. Active patients (>7,500 steps/day) had significantly fewer comorbidities (4 comorbidities) compared to severely inactive patients (<2,500 steps/day, 6 comorbidities), and muscle weakness and high symptoms of depression were less prevalent. Severely inactive patients had significantly more cardiovascular comorbidities compared to all other groups. No other significant differences were observed.

CONCLUSION

Physically active lung transplant recipients have fewer comorbidities, lower prevalence of muscle weakness, and fewer symptoms of depression compared to very inactive patients.

The prevalence of osteopenia and osteoporosis after heart transplantation assessed using CT

OBJECTIVE

Osteoporosis is frequently observed in patients after heart transplantation (HT), although the prevalence long-term post-HT is unknown. Most studies investigating bone mineral density (BD) after HT were performed using dual-energy X-ray absorptiometry. In this study BD, including the prevalence of osteopenia and osteoporosis, was investigated using coronary computed tomography (CCT) long-term post-HT. Moreover, risk factors for abnormal BD were investigated.

METHODS

All first CCT scans between February 2018 and June 2020 used for the annual screening for cardiac allograft vasculopathy were included. Retransplantations and scans with not fully imaged vertebrae were excluded. BD was measured as a mean of the BD of three consecutive thoracic vertebrae and categorized into normal BD, osteopenia or osteoporosis. Binary logistic regression was used to find determinants for an abnormal BD. Linear regression was used to explore determinants for the mean Hounsfield unit (HU) value of the BD.

RESULTS

In total, 140 patients were included (median age 55.2 [42.9-64.9] years, 51 (36%) female). Time between HT and CT scan was 11.0 [7.3-16.1] years. In total, 80 (57%), 43 (31%), and 17 (12%) patients had a normal BD, osteopenia, or osteoporosis, respectively. Osteoporotic fracture or vertebrae fractures was seen in 11 (8%) patients. Determinants for an abnormal BD were recipient age (OR 1.10 (1.06-1.14), p<0.001) and prednisolone use (OR 3.75 (1.27-11.01), p=0.016). In linear regression, left ventricular assist device use pre-HT (p=0.024) and time since HT (p=0.046) were additional BD determinants.

DISCUSSION

Osteopenia and osteoporosis are frequently seen on CCT post-HT. More investigation on appropriate measures to maintain a normal BD in these patients are needed.

Osteoporosis and risk of fracture in heart transplant patients

Introduction

Significant bone loss occurs after heart transplantation, predominantly in the first year, with increased risk of incident fractures. The goal of this study was to evaluate the prevalence of fragility fractures in a population of heart transplantation patients and to identify the independent risk factors for fractures.

Methods

This was a prospective monocentric study that included patients with heart transplantation occurring < 10 years who were undergoing heart transplantation monitoring. All patients underwent bone mineral density evaluation by dual-energy X-ray absorptiometry and radiographies to establish the presence of vertebral fractures.

Results

We included 79 patients (61 men); the mean age was 56.8 ± 10.8 years. The mean time between transplantation and inclusion was 32.3 ± 35.0 months. Incident fractures were diagnosed in 21 (27%) patients after heart transplantation. Vertebral fractures were the most frequent (30 vertebral fractures for 15 patients). Osteoporosis was confirmed in 22 (28%) patients. Mean bone mineral density at the femoral neck and total hip was lower with than without fracture (femoral neck: 0.777 ± 0.125 vs 0.892 ± 0.174 g/cm2, p<0.01; total hip: 0.892 ± 0.165 vs 0.748 ± 0.07 g/cm2, p<0.001), with a significant result on multivariate analysis. The mean time from transplantation to the first fracture was 8.0 ± 7.6 months.

Discussion

Our study confirmed a high vertebral fracture risk in heart transplant patients, especially during the first year after transplantation.

High risk of osteoporosis and fracture following solid organ transplantation: a population-based study

Background

Osteoporosis and fractures increase morbidity and mortality rates after solid organ transplantation (SOT), but few studies have analyzed the risk of osteoporosis and related fractures after SOT. In this retrospective cohort study, we investigated the risk of osteoporosis and fractures in different SOT recipients.

Methods

This study was a retrospective cohort study using a nationally representative database in Taiwan. We collected the data of SOT recipients and used the propensity score matching method to obtain a comparison cohort. To reduce bias, we excluded patients who had been diagnosed with osteoporosis or fracture before inclusion. All participants were followed up until the date of diagnosis as having a pathological fracture, death, or the end of 2018, whichever occurred first. The Cox proportional hazards model was used to investigate the risk of osteoporosis and pathological fracture in SOT recipients.

Results

After adjustment for the aforementioned variables, SOT recipients were observed to have a higher risk of osteoporosis (hazard ratio (HR) = 1.46, 95% confidence interval (CI): 1.29-1.65) and fracture (HR: 1.19, 95% CI: 1.01-1.39) than the general individuals. Among the different SOT recipients, the highest risk of fractures was noted in heart or lung transplant recipients, with a HR of 4.62 (95% CI: 2.05-10.44). Among the age groups, patients aged >61 years had the highest HRs for osteoporosis (HR: 11.51; 95% CI, 9.10-14.56) and fracture (HR: 11.75, 95% CI: 8.97-15.40).

Conclusion

SOT recipients had a higher risk of osteoporosis and related fractures than the general population, with the highest risks observed in patients receiving heart or lung transplants, older patients, and patients with CCI scores of >3.

Bone health outcomes in post-lung transplant patients with cystic fibrosis

BACKGROUND

Osteoporosis is a common comorbidity in patients with cystic fibrosis (CF). Although lung transplantation (LTx) improves quality of life of CF patients, there is little research examining long-term bone health outcomes following LTx in these patients.

METHODS

Data were collected on 59 patients who underwent LTx between 2006 and 2019, including 30 with CF and 29 without CF. We compared baseline characteristics, long-term bone mineral density (BMD) trends, and fracture incidence between the two patient populations, and examined factors associated with post-LTx fractures in CF patients.

RESULTS

Compared with non-CF patients, patients with CF were younger, had lower body mass index, and lower baseline BMD Z-scores at the lumbar spine, femoral neck, and total hip (all p<0.001). BMD at all sites declined in both groups in the first year post-LTx. In subsequent years, CF patients exhibited better BMD recovery relative to pre-transplantation, but continued to have lower BMD post-LTx. Post-transplant fractures occurred in 30% and 34% of CF and non-CF patients, respectively. CF patients who developed fractures after LTx had significantly lower BMD and lower pre-transplantation percent predicted forced expiratory volume in one second (FEV1%).

CONCLUSIONS

Although CF patients exhibit better BMD recovery following LTx compared to their non-CF counterparts, CF patients start with significantly lower pre-LTx BMD and experience a similarly high rate of post-LTx fractures. These findings highlight the unique contribution of the CF disease process to bone health, as well as a clear need for better prevention and treatment of osteoporosis in CF patients before and after LTx.

Common Noninfectious Complications Following Lung Transplantation

According to the Scientific Registry of Transplant Recipients, both transplant volume and survival among lung transplant recipients are improving over time. However, the outcomes of lung transplantation remain challenged by multiple thoracic and extrathoracic complications. With improving lung transplant survival, patients experience prolonged exposure to chronic immunosuppressive agents that can lead to multiple infectious and noninfectious complications. This article focuses on most common noninfectious complications with significant clinical impact.

Bone health and cardiac transplantation

Patients who undergo heart transplantation (HT) have increased loss of bone mineral density (BMD) [g/cm2]. The greatest drop in BMD occurs within the first year after HT with a decrease 3.5-8.5% in the lumbar spine and 5.6-10.5% in the femoral neck. Thereafter, BMD tend to stabilize or even recover to some degree. Accordingly, risk of fracture correlates to BMD evolution, with the highest rate of fractures during the first year, with a cumulative incidence of 12-36%. Fragility fractures contributes to increased morbidity and increased mortality. The pathophysiology behind BMD impairment in HT patients is complex and involves side-effects of the immunosuppressive therapy and of heart failure medications, as well as organ failure. Of the immunosuppressive agents, corticosteroids (CS) exerts the greatest impact on BMD through multiple cellular pathways. Also, calcineurin inhibitors seem have a negative impact on BMD, mainly mediated through enhancement of bone resorption. Additionally, kidney dysfunction has a significant effect on bone homeostasis and is frequently present in HT patients. The optimal timing and type of pharmacological treatment of osteoporosis in HT patients are not yet known. However, bisphosphonates and monoclonal antibody against RANK ligand (Denosumab) may have beneficial effects on bone metabolism in HT patients. However, their efficacy and safety in have not been thoroughly studied in this particular patient population. Therefore, careful individual evaluation of prescription, frequency, and possible treatment options is advisable in this patient population.

Impact of Vitamin D Supplementation on Bone Mineral Density and All-Cause Mortality in Heart Transplant Patients

Vitamin D (VD) deficiency is frequently reported in heart transplant (HT) recipients and routinely supplemented. However, the efficacy of VD supplementation on bone mineral density (BMD) and its association with all-cause mortality is underinvestigated. The VD levels and BMD were studied for two years, and the association of VD and BMD with all-cause mortality risk was investigated. Ninety-six HT patients (38.18 ± 12.10 years old; 74% men) were followed up during VD, Ca, and Mg supplementation. Anthropometric measurements, BMD by Dual-energy X-ray absorptiometry (DEXA) scan, VD concentrations, and related biochemical parameters were analyzed before, 1 year, and 2 years after HT. Despite significant improvement of VD₃ and 25-hydroxy VD (25OHVD) levels especially in the men, BMD parameters were insignificantly changed. After 2 years, the all-cause mortality rate was 15.6%. High pretransplant levels of 25OHVD failed to improve the survival probability. Cox’s regression showed a 32.7% increased hazard ratio for each unit increase in body mass index (95% CI: 1.015–1.733, p = 0.038), in the VD-deficient group rather than in the VD-sufficient one. In conclusion, VD supplementation improves the biochemical status, especially in VD-deficient HT. However, its impact on the BMD and mortality was not as usually expected. Further investigation of the disturbed VD metabolism in HT is warranted.

Survival and Nutritional Status of Male and Female Heart Transplant Patients Based on the Nutritional Risk Index

Malnutrition among heart-transplant patients may affect survival. The aim was to investigate the survival and nutrition status among male and female heart transplant patients who underwent transplantation, before and 1 year after surgery based on the nutritional risk index (NRI). The medical records of ninety heart-transplant patients (2009–2014) from the King Faisal Specialist Hospital, Riyadh, were reviewed. The assessment included demographic data, anthropometric measurements, and NRI calculation. Moreover, postoperative data included the length of stay and survival. Paired t-test and survival analysis by Kaplan–Meier (KM) curves were used. A total of 90 patients (males 77.78%) were included. The prevalence of malnutrition in the preoperative phase by NRI was 60% (7.78% as severe; 40% as moderate, and 12.22% mild NRI scores). After 1 year, body mass index (BMI) and NRI increased significantly (p < 0.001). Furthermore, NRI was significantly different between men and women (p < 0.01), while KM survival curves were insignificantly different (p = 0.67). Recipients with postoperative moderate or severe nutritional risk (NRI < 97.5) had significantly shorter survival in the first-year post-transplantation (HR = 0.82; 95% CI, 0.75–0.89; p < 0.001). Our findings indicate that the NRI after 1 year of transplant correlated significantly with mortality. Besides, there was no significant gender difference regarding survival; however, malnutrition and low survival were more prominent among women.

Long-term bone mineral density changes and fractures in lung transplant recipients with cystic fibrosis

BACKGROUND

Little is known about long-term bone mineral density (BMD) changes and fractures in lung transplant recipients with cystic fibrosis (CF). We examined femur and lumbar spine (LS) BMD changes in men and women with CF up to 10 years post-transplant and documented post-transplant fracture prevalence.

METHODS

Retrospective study of individuals who had undergone a lung transplant (2000-2015) and had a pre-transplant and at least one BMD measurement after transplant. Vertebral fractures were assessed on chest computed tomography scans and other fractures abstracted from medical records.

RESULTS

The cohort consisted of 131 individuals; 53% males, median age: 28 years [interquartile range: 24-35] and 31% having pre-transplant low bone mass. Most recipients were given bisphosphonates after transplant with proportion reaching 94% at 10 years. Up to 10 years post-transplant, men experienced positive or little change in LS BMD, indicating minimal loss from pre-transplant values. In contrast, women displayed negative changes in BMD up to 5 years post-transplant before recovering pre-transplant BMD values by 10 years. Similar patterns were observed at the femur BMD where men demonstrated a lower bone loss and faster recovery towards pre-transplant values than women. After transplant, 88% of recipients maintained their pre-transplant bone status, 3% experienced an improvement, mostly progressing from low bone mass to normal status whereas 9% had a deterioration of their pre-transplant bone status. Twenty-seven recipients suffered fractures in the post-transplant period.

CONCLUSIONS

These findings underline that lung recipients with CF remain at risk of skeletal fragility despite prompt initiation of post-transplant anti-osteoporosis therapy.

Timing of Osteoporotic Vertebral Fractures in Lung and Heart Transplantation: A Longitudinal Study

Bone loss and bone fractures are common complications after organ transplantation. Many factors contribute to the pathogenesis of transplant osteoporosis, such as bone disease preceding transplantation, immunosuppressive medications, and nutritional and lifestyle factors. This study aimed to assess the incidence of vertebral fractures before and after lung and heart transplantation. This longitudinal study analyzed 213 electronic medical records of patients who underwent lung transplantation (n = 128) and heart transplantation (n = 85) at Siena University Medical Center between January 2000 and December 2018. In lung and heart transplant recipients, the bone mineral density in the femoral sub-regions show a significant decrease at post-transplantation and at follow up visits. In both lung and heart recipients, we found an increase in the fracture incidence in the first period after transplantation (19.5% vs. 50.4% in lung recipients; 9.6% vs. 25.7% in heart recipients). Moreover, in lung recipients, vertebral fractures were predicted primarily by age, BMD at the femur, and any history of fracture. In heart recipients, vertebral fractures were predicted only by history of fracture. Our study supports the recommendations for pre-transplant osteoporosis screening in patients undergoing lung transplants, and in the first period after transplantation in heart transplant recipients.

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.

Bone Mineral Density in Relation to Chronic Kidney Disease After Heart Transplantation: A Retrospective Single-center Study at Skåne University Hospital in Lund 1988-2016

Background.

Our aim was to investigate the bone mineral density (BMD) evolution and incidence of osteoporosis in relation to chronic kidney disease (CKD) up to 10 years after heart transplantation (HT).

Methods.

A retrospective analysis was performed on 159 HT patients at Skåne University Hospital in Lund 1988–2016.

Results.

The median follow-up time was 6.1 years (interquartile range = 7.5 y). HT patients with CKD stage <3 or normal kidney function before HT exhibited a greater mean BMD loss in the lumbar spine, compared to patients with CKD stage ≥3 before HT, at the first (−6.6% versus −2.5%, P = 0.029), second (−3.7% versus 2.1%, P = 0.018), and third (−2.0% versus 4.1%, P = 0.047) postoperative years, respectively. All included HT patients exhibited a BMD loss in the femoral neck at the first postoperative year (−8.8% [−10.3 to −7.3] in patients with CKD stage <3 or normal kidney function and −9.3% [−13.2 to −5.5] in patients with CKD stage ≥3 before HT), which was not fully reversed up to 10 years after HT. In adjusted models, CKD stage <3 before HT did not predict osteopenia and osteoporosis in the lumbar spine or femoral neck.

Conclusions.

CKD before HT did not predict BMD loss or osteoporosis development after HT. The study is, however, limited by a lack of data on fractures, and further studies on the relationship between CKD and postoperative bone strength are encouraged.

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.

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.

The Role of Tumor Necrosis Factor Alpha and TNF Superfamily Members in Bone Damage in Patients with End-Stage Chronic Obstructive Lung Disease Prior to Lung Transplantation

A disequilibrium of tumor necrosis superfamily (TNF) members, including the serum osteoprotegerin, soluble receptor activator of nuclear factor-κB ligand, soluble TNF-related apoptosis-inducing ligand and TNF-α, was associated with the occurrence of a reduced skeletal mass and osteoporosis in male patients with end-stage chronic obstructive pulmonary disease (COPD). The purpose of this study was to explore the associations between serum biomarkers of tumor necrosis factor (TNF) superfamily and body and bone compositions in end-stage COPD males. Pulmonary function, T-score at the lumbar spine and femoral neck, lean mass, serum osteoprotegerin (OPG), soluble receptor activator of nuclear factor-κB ligand (sRANKL), TNF-α and its receptors (sTNFR-I, sTNFR-II) and soluble TNF-related apoptosis-inducing ligand (sTRAIL) levels were evaluated in 48 male patients with end-stage COPD and 36 healthy male volunteers. OPG was lower in male COPD patients than in control subjects, whereas sRANKL, TNF-α and its receptors were higher. The serum sTRAIL level showed a tendency to increase compared with that of healthy subjects (P = 0.062). Serum OPG showed a positive correlation with bone density. In contrast, serum TNF-α, sRANKL and sTRAIL were inversely associated with pretransplant bone density. We have noted the appearance of statistically significant inverse relationships between lean mass values and TNF-α, sTNFR-I and II and sRANKL levels in male COPD patients. Moreover, there was a negative correlation between sTRAIL levels with airway obstruction (P = 0.005) and hypercapnia (P = 0.042) in advanced COPD patients. Through a multiple linear regression analysis, our study revealed that a disequilibrium of TNF family members was strongly associated with the occurrence of a reduced skeletal mass and osteoporosis. These results provide further evidence that abnormal levels of TNF superfamily molecules may cause not only a decrease in BMD, but also lower muscle mass in end-stage COPD.

Bone Mineral Density and Fat-Soluble Vitamin Status in Adults with Cystic Fibrosis Undergoing Lung Transplantation: A Pilot Study

Purpose: Patients with cystic fibrosis (CF) often experience low bone mineral density (BMD) pre- and post-lung transplantation (LTX). The study purpose was to describe BMD and micronutrient status in adults with CF pre- and post-LTX.

Methods: Twelve patients with CF (29 ± 8 years) were recruited from the CF clinic at the University of Alberta Lung Transplant Program. BMD and vitamins A, D, E, K status, and parathyroid hormone were measured pre- and post-LTX.

Results: No significant differences pre- and post-LTX were observed at the different bone sites measured (lumber–spine, femoral–neck (FN), hip, and femoral–trochlea) (P > 0.05). BMD T-scores (<−2) was present in lumbar–spine, FN, hip, and femoral–trochlea in 33%, 17%, 17%, and 25% of individuals pre-LTX and 58%, 33%, 58%, and 33% of individuals post-LTX, respectively. More than 50% of patients had suboptimal vitamin K levels (PIVKA-II values >3 ng/mL) pre- and post-LTX.

Conclusion: Adults with CF pre- and post-LTX had reduced BMD and suboptimal vitamin K status.

Role of vascular remodeling markers in the development of osteoporosis in idiopathic pulmonary arterial hypertension

Aim. To define the role of circulating biomarkers for the metabolism of collagen and intercellular substance and vascular remodeling in the development of osteoporosis (OP) in idiopathic pulmonary arterial hypertension (IPAH). Materials and methods. Functional hemodynamic parameters, bone mineral density (BMD) in the lumbar spine and femoral neck and the serum levels of matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1), MMP-9/TIMP-1 complex, C-terminal telopeptide of collagen type 1 (CITP), and endothelin-1 (ET-1) were determined in 27 high-risk IPAH patients and 30 healthy volunteers. Results. OP in IPAH was detected in 50% of the examinees. The serum levels of CITP, MMP-9, TIMP-1, and ET-1 proved to be higher in the high-risk IPAH patients than in the healthy volunteers. There was a direct correlation between BMD and six-minute walk test and an inverse correlation with total pulmonary vascular resistance (TPVR). Serum TMIP-1 levels correlated with cardiac index and TPVR; ET-1 concentrations were directly related to pulmonary artery systolic pressure, cardiac index, and TPVR. Inverse relationships were found between BMD and circulating CITP, MMP-9, TMIP-1, MMP-9/TMIP-1, and ET-1. At the same time, there was only a tendency towards a positive correlation between serum CITP and ET-1 concentrations. Conclusion. The results of the investigation confirm that endothelin system dysregulation plays a leading role in the development of persistent hemodynamic disorders in high-risk IPAH and suggest that it is involved in the development of osteopenic syndrome. Enhanced ET-1 secretion initiates bone loss possibly via activation of connective tissue matrix destruction.

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.

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.

Sirolimus and tacrolimus rather than cyclosporine A cause bone loss in healthy adult male rats

The aim of this work was to study the effects of cyclosporine (CsA), tacrolimus (FK-506), and rapamycin (RAPA) on bone mass, femoral microstructure, femoral biomechanical properties, and bone remodeling in healthy adult male rats.

Forty-eight 5-month-old male Wistar rats were used. CsA (2 mg/kg/day), FK-506 (3 mg/kg/day), RAPA (1.25 mg/kg/day), or water (0.5 ml/rat/day, control group) were administered orally for 3 months.

After sacrifice, mean values of immunosuppressants in blood were: CsA (670.4 ng/ml), FK-506 (19.2 ng/ml), and RAPA (4.8 ng/ml). Levels of biochemical parameters were normal in all groups. Femoral BMD was decreased in FK-506 and RAPA groups and lumbar BMD in FK-506 group. Trabecular volume fraction (BV/TV) decreased only in FK-506 group. RAPA and CsA affected femoral cortical structure, but FK-506 did not. FK-506 produced an increase in bone remodeling, and CsA a decrease. FK-506 group showed a decrease in biomechanical parameters relative to all groups. RAPA group showed a decrease in ultimate stress vs control group, and CsA group presented an increase in biomechanical parameters versus control group.

We found that administration of both RAPA and FK-506 as monotherapy for healthy rats produced osteopenia. CsA treatment only produces slight damages in the cortical zone of the femur.

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.