Evidence of continuing bone recovery at a mean of 7 years after liver transplantation

Changes in thoracic radio density after living donor liver transplantation

BACKGROUND

The outcomes after liver transplantation have greatly improved, which has resulted in greater focus on improving non-hepatic outcomes of liver transplantation. The present study aimed to evaluate thoracic spine radio density in children and adolescents after liver transplantation.

METHODS

A total of 116 patients who underwent living donor liver transplantation were retrospectively analyzed. The radio density at the eleventh thoracic vertebra was measured using computed tomography scan performed preoperatively then annually for 5 years postoperatively and subsequently every 2 or 3 years.

RESULTS

The mean thoracic radio density of male recipients of male grafts had the lowest values during the study. The radio density of patients receiving a graft from a female donor was higher than in recipients with grafts from males. Total mean radio density decreased for first 5 years postoperatively and then increased. Changes in radio density were equally distributed in both steroid withdrawal and no steroid withdrawal groups for 5 years, after which patients with steroid withdrawal had a greater increase. Changes in radio density were equally distributed in both the steroid withdrawal and no steroid withdrawal groups up to age 20, after which patients in the steroid withdrawal group had a greater increase.

CONCLUSIONS

Gender differences may affect the outcome of radio density changes after transplantation. Given the moderate association between thoracic radio density and bone mineral density in skeletally mature adults and further studies are needed to validate this relationship between thoracic radio density and bone mineral density changes in pediatric liver transplantation.

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.

Increased Imminent Fracture Risk in Liver Transplant Recipients Despite Bisphosphonate Therapy

BACKGROUND

Bone loss is significant after orthotopic liver transplant (OLT) and is associated with increased fracture risk and decreased quality of life. In post-transplant fracture prevention, the cornerstone of therapeutic management is bisphosphonates.

METHODS

We conducted a retrospective study in a cohort of 155 OLT recipients who received a bisphosphonate prescription at hospital discharge between 2012 and 2016 to investigate post-OLT fragility fracture incidence and predictive risk factors.

RESULTS

Before OLT, 14 patients presented a T score < -2.5 SD, and 23 patients (14.8%) had a history of fracture. During follow-up, the cumulative incidence of fractures on bisphosphonates (99.4% risedronate/alendronate) was 9.7% at 12 months and 13.1% at 24 months. The median time to first fragility fracture was 10 months (IQR, 3-22 months) and thus within the first 2 years of follow-up. Predictive factors of fragility fractures in multivariate Cox regression analyses included age 60 years or older (hazard ratio [HR], 2.61; 95% CI, 1.14-6.01; P = .02), post-transplant diabetes mellitus (HR, 3.82; 95% CI, 1.55-9.44; P = .004), and cholestatic disease (HR, 5.93; 95% CI, 2.30-15.26; P = .0002). Additionally, the female sex was associated with a strong trend toward increased fracture risk in univariate analysis (HR, 2.27; 95% CI, 1.00-5.15; P = .05), as well as a post-transplant absolute decrease in bone mineral density at the femoral neck and total hip (P = .08).

CONCLUSIONS

This real-world study reports a high incidence of fractures post-OLT despite bisphosphonate therapy. Age 60 years or older, post-transplant diabetes mellitus, cholestatic disease, female sex, and femoral neck and/or total hip bone mineral density loss contribute to increased imminent fracture risk in liver transplant recipients.

A systematic review and meta-analysis on the incidence of osteoporosis and fractures after liver transplant

Following liver transplant (LT), osteoporosis is a severe complication that causes morbidity. However, the incidence and risk factors of osteoporosis and fractures have not been well described. Single-arm meta-analysis of studies reporting osteopenia, osteoporosis, and fractures post-LT was performed with meta-regression for study period. Dichotomous variables, continuous variables and time-to-event variables were pooled in odds ratio, weighted mean difference and hazard ratio, respectively. For risk factors with limited data, a systematic review of literature was conducted. There was a significant increase in both osteoporosis and fractures compared to non-LT patients. Osteopenia, osteoporosis and incident fractures were newly diagnosed in 34.53% (CI: 0.17-0.56, n = 301), 11.68% (CI: 0.05-0.24, n = 1251) and 20.40% (CI: 0.13-0.30, n = 4322) of LT patients, respectively. Female gender (P = 0.017) increased risks of osteoporosis but not older age and BMI. Older age, lower pre-LT bone mineral density (BMD), presence of bone disease pre-LT were significant risk factors for fractures but not female gender, post-menopausal state, BMI, smoking and alcohol. There is a high incidence of skeletal complications post-LT. Older age, lower pre-LT BMD and presence of bone disease pre-LT are significant risk factors that are associated with incident fractures physicians should be cognisant of in liver transplant recipients.

Evaluation of Factors Associated With Fracture and Loss of Bone Mineral Density Within 1 Year After Liver Transplantation

OBJECTIVE

Orthotopic liver transplant recipients are at high risk of fragility fractures both in pre-liver transplant (pre-LT) and in the immediate posttransplant (post-LT) period. The aims of this study were to identify risk factors associated with post-LT fracture and identify factors that contribute to changes in bone mineral density (BMD) in post-LT as they relate to the risk of fracture in the immediate post-LT period.

METHODS

We conducted a retrospective cohort study of first-time LT recipients who had BMD testing within 2-year pre-LT and 1-year post-LT. We assessed factors associated with immediate post-LT fracture using logistic regression models and linear regression models.

RESULTS

New fractures occurred in 41/286 (14.3%) of LT recipients during the first year following LT. In multivariate analysis, we noted an increased odds of fracture for patients with prior history of fracture (P < .001), patients who were older (P = .03), patients with higher end-stage liver disease score (P = .03), and patients with lower BMD. After adjustment for multiple testing, only a history of prior fracture was statistically significant.

CONCLUSION

Our study demonstrated that prior fracture at any site was associated with developing a new fracture in the first year post-LT.

The Impact of Tenofovir Disoproxil Fumarate on Reduced Bone Mineral Density and Fractures in Liver Transplant Recipients

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is associated with reduced bone density in patients with human immunodeficiency virus, but the effect of TDF on bone density in liver transplant (LT) recipients is unknown.

METHODS

We performed a single-center, retrospective study of LT recipients with hepatitis B taking TDF compared to a control group with non-hepatitis B virus viral hepatitis. The primary outcome was reduced bone density, defined as femoral neck or lumbar T-score less than -1. Other outcomes included mean T-score and fractures.

RESULTS

Three hundred ninety-three patients were studied: 52 patients in the TDF group and 341 patients in the control group; 64.3% patients in the TDF group had reduced bone density vs 71.4% in the control group (P = .58) before LT, compared to 75% and 81.5% (P = .57), respectively, after LT. Mean posttransplant lumbar T-scores were lower in the TDF group (-1.74 vs -0.75, P = .04). There was no difference between the 2 groups for the other outcomes. In a multivariate Cox proportional hazards model, TDF use did not affect the risk of post-LT reduced bone density (hazard ratio = 0.99; 95% confidence interval, 0.56-1.76; P = .97).

CONCLUSION

TDF use was not associated with reduced bone mineral density or increased rates of fractures in LT recipients compared to controls in this study.

Bone Mineral Density of Very Long-term Survivors After Childhood Liver Transplantation

OBJECTIVES

Liver transplant patients are at risk of osteopenia and fractures but limited information is available in long-term survivors after childhood transplantation. This study aimed to assess bone mineral density (BMD) of very long-term, >5 years, survivors after liver transplantation in childhood.

METHODS

Patients aged <18 years at transplant, having survived >5 years after transplant were potentially eligible but only those with ongoing review in our state were included. Dual-energy x-ray absorptiometry (DXA) was used to measure BMD. Patients aged <20 years had lumbar spine (LS) and total body (TB) measurements whereas those aged 20 years or more had LS and femoral neck but not TB. BMD z-scores for LS and TB, if available, were used in this study. BMD z-score ≤-2.0 was considered reduced. Pre-pubertal children had radiologic bone age assessment.

RESULTS

Forty-two patients, 17 boys, participated of whom 64% had biliary atresia. Median age at transplant was 2.22 (range 0.38-14.25) years; time since transplant 10.10 (5.01-25.98) years; and age at DXA 14.64 (6.59-38.07) years. Mean BMD z-scores were LS -0.15 ± 1.07, and TB -0.76 ± 1.14, with no sex difference noted. Four (9.5%) patients had reduced LS BMD, and although ongoing steroid use was more frequent in these patients, other comorbidities were likely important. Age at transplant, time since transplant, height, weight, and body mass index at DXA did not predict LS BMD. Pathologic fractures occurred in 2 of 42 (5%) patients; all within 18 months of transplant.

CONCLUSIONS

Very long-term survivors after childhood liver transplant have LS BMD within the normal range.

The impact of osteoporosis on health-related quality of life in patients after liver transplantation - a pilot study

Introduction

Liver transplantation (LT) is now a well-established procedure with 5-year survival rates over 70%, and one of its ultimate goals is the improvement of patient health-related quality of life (HRQOL). Osteoporosis remains a serious potential complication of LT, leading to fragility fractures, pain, and functional impairment.

Aim

To assess the degree of osteoporosis and the impact of fragility fractures on HRQOL in patients with chronic liver diseases treated with LT.

Material and methods

Twenty-seven patients (14 female, 13 male) at a median period of 3.5 years post LT participated in the study. HRQOL was assessed by Short Form-36 and PBC-40 instruments. Bone mineral density (BMD) in the lumbar spine and hip neck were measured by dual-energy X-ray absorptiometry. Physical activity was assessed by questionnaire. Data on the duration of the liver disease, time from LT, and fragility fractures were also collected.

Results

As many as 74.1% of the patients had reduced BMD (t-score < -1.0 SD) in the hip. Mean values of the spine and hip BMD z-scores were -1.1 and -0.9 SD, respectively. Time after LT, percentage of lean tissue, and physical activity were positively associated with BMD. The prevalence of fractures was 48%. We did not find significant differences in age, gender, body composition parameters, physical activity, BMD, and HRQOL scores between the subjects with and without fractures.

Conclusions

We found a high prevalence of fragility fractures and a decreased BMD in LT recipients. Patients with a history of fractures had similar HRQOL scores to those without fractures.

Longitudinal changes in BMD and fracture risk in orthotopic liver transplant recipients not using bone-modifying treatment

Osteoporosis is prevalent in end-stage liver disease, but data on long-term changes in bone mineral density (BMD) and related fracture incidence after orthotopic liver transplantation (OLT) are scarce. We evaluated BMD changes up to 5 years in consecutive recipients of a successful OLT at the Leiden University Medical Centre between 2000 and 2011, in whom sequential BMD data were available. Spinal radiographs were available at time of screening and at 6 and 12 months post-OLT and were assessed for vertebral fractures by two independent observers using Genant's semiquantitative method. Patients were excluded from the study when started on bisphosphonates. A total of 201 patients (71% men), median age 53 years (range, 18-70 years) were included in the study. Most common liver pathology was viral (27%) or alcoholic liver disease (25%). All patients received prednisone for at least 6 months after transplantation and the majority received either tacrolimus or cyclosporine for immunosuppression. At time of screening for OLT, osteoporosis and osteopenia were found in 18% and 36% of patients at the lumbar spine (LS), respectively, and in 9% and 42% at the femoral neck (FN), respectively. T-scores declined significantly at both sites 6 months after OLT, but increased thereafter at the LS, reaching pretransplantation values at 2 years and remaining stable thereafter. FN T-scores remained consistently lower than pretransplantation values. The prevalence of vertebral fractures increased from 56% at screening to 71% at 1 year after OLT, with a fracture incidence of 34%. BMD changes did not predict fracture risk. Osteoporosis, osteopenia, and vertebral fractures are prevalent in patients with end-stage liver disease. An overall decline in BMD is observed within the first 6 months after OLT, with subsequent recovery to pretransplantation values at the LS, but not at the FN. Vertebral fracture risk is high after OLT regardless of changes in BMD.

Treatment of osteoporosis in patients with chronic liver disease and in liver transplant recipients

The pathogenesis of osteoporosis in chronic liver disease and post-liver transplantation is complex and heterogeneous. The development of hepatic osteodystrophy may be related to both increased bone resorption and decreased bone formation. Available medical treatments can be broadly classified into antiresorptive and bone-stimulating agents. Most published studies on the treatment of osteoporosis in patients with liver disease have used the commonly prescribed antiosteoporosis drugs approved for postmenopausal osteoporosis. These studies have included a small number of subjects and used bone mineral density (BMD) changes rather than fracture occurrence as an endpoint because of the short follow-up. Although the increases in BMD are promising, no intervention is proven to have antifracture efficacy in hepatic osteodystrophy. The natural history of bone disease following liver transplantation has not been fully investigated, although studies suggest that bone mineral loss is transient and generally reverses within a year following transplantation. The approach to treatment in liver transplant recipients should be targeted at preventing the early bone loss without interfering with the later recovery. Based on the available data, no single available agent can be considered as first-line therapy. In our opinion, the best treatment approach involves the elucidation of modifiable risk factors and the selection of agents targeted at the underlying derangements.

Endocrine and bone metabolic complications in chronic liver disease and after liver transplantation in children

With improved survival of orthotopic liver transplantation (OLT) in children, prevention and treatment of pre- and posttransplant complications have become a major focus of care. End-stage liver failure can cause endocrine complications such as growth failure and hepatic osteodystrophy, and, like other chronic illnesses, also pubertal delay, relative adrenal insufficiency, and the sick euthyroid syndrome. Drug-induced diabetes mellitus post-OLT affects approximately 10% of children. Growth failure is found in 60% of children assessed for OLT. Despite optimisation of nutrition, rarely can further stunting of growth before OLT be prevented. Catch-up growth is usually observed after steroid weaning from 18 months post-OLT. Whether growth hormone treatment would benefit the 20% of children who fail to catch up in height requires testing in randomised controlled trials. Hepatic osteodystrophy in children comprises vitamin D deficiency rickets, low bone mass, and fractures caused by malnutrition and malabsorption. Vitamin D deficiency requires aggressive treatment with ergocalciferol (D2) or cholecalciferol (D3). The active vitamin D metabolites alphacalcidol or calcitriol increase gut calcium absorption but do not replace vitamin D stores. Prevalence of fractures is increased both before OLT (10%-28% of children) and after OLT (12%-38%). Most fractures are vertebral, are associated with low spine bone mineral density, and frequently occur asymptomatically, but they may also cause chronic pain. Fracture prediction in these children is limited. OLT in children is also associated with a greater risk of developing avascular bone necrosis (4%) and scoliosis (13%-38%). This article reviews the literature on endocrine and skeletal complications of liver disease and presents preventive screening recommendations and therapeutic strategies.

Changes in vitamin D binding protein and vitamin D concentrations associated with liver transplantation

BACKGROUND

Vitamin D deficiency is associated with fractures, infections and death. Liver disease impairs vitamin D and vitamin D binding protein (DBP) metabolism.

AIMS

We aimed to determine the impact of liver transplantation on vitamin D, particularly on DBP and free vitamin D concentrations.

METHODS

Serum 25(OH)D, 1,25(OH)(2) D and DBP concentrations were measured in 202 adults before liver transplantation and 3 months later in 155. Free vitamin D concentrations were estimated from these values. Risk factors for 25(OH)D deficiency (<20 ng/ml) and low 1,25(OH)(2) D (<20 pg/ml) were examined with logistic regression, and changes in concentrations following transplantation with linear regression.

RESULTS

Pretransplant, 84% were 25(OH)D deficient, 13% had 25(OH)D concentrations <2.5 ng/ml, and 77% had low 1,25(OH)(2) D. Model for end-stage liver disease score ≥ 20 (P < 0.005) and hypoalbuminemia (P < 0.005) were associated with low 25(OH)D and 1,25(OH)(2) D concentrations. Following transplantation, 25(OH)D concentrations increased a median of 17.8 ng/ml (P < 0.001). Albumin increased from a median of 2.7 to 3.8 g/dl (P < 0.001) and DBP from 8.6 to 23.8 mg/dl (P < 0.001). Changes in total 25(OH)D were positively and independently associated with changes in DBP (P < 0.05) and albumin (P < 0.001). Free 25(OH)D concentrations rose from 6.0 to 9.7 pg/ml (P < 0.001). In contrast, total 1,25(OH)(2)D concentrations rose only by 4.3 pg/ml (P < 0.001) and free 1,25(OH)(2D concentrations declined (P < 0.001).

CONCLUSIONS

Serum total and free 25(OH)D and DBP concentrations rose substantially following transplantation, while 1,25(OH)(2) D concentrations showed modest changes and free 1,25(OH)(2) D decreased. Studies of the effects of vitamin D status on diverse transplant complications are needed.

Medical management of the liver transplant recipient

Long-term survival of liver transplant recipients has become the rule rather than the exception. As a result, the medical complications of long-term survival, including atherosclerotic cardiovascular disease, metabolic bone disease, and de novo malignancy, have accounted for an increasing proportion of late morbidity and mortality. Risk factors for these complications begin before transplant and are potentially modifiable but are exacerbated by the requirement for immunosuppressive medications after transplantation. Surveillance and early intervention programs administered by transplant hepatologists and other medical subspecialists may improve long-term outcomes in liver transplant recipients by ameliorating risk factors for atherosclerosis, bone fractures, and cancer.

Osteoporosis following organ transplantation: pathogenesis, diagnosis and management

Organ transplantation has become popular for the management of various chronic illnesses. With the advent of modern immunosuppressive treatments, the longevity of transplant recipients has increased. Consequently, morbid complications such as osteoporosis and bone fractures are seen at an increasing frequency in this population. In most transplant recipients, bone mineral density (BMD) falls shortly after transplantation. However, bone fracture rate plateaus in all except for post-renal transplant patients. Although the underlying pathophysiologic mechanism for this difference is not fully understood, potential mechanisms for sustained bone loss in renal transplant recipients may be persistent phosphorus wasting and defective bone mineralization. Current treatment regimens are based on studies in a small numbers of subjects with BMD as the primary outcome. Although BMD is recognized as a gold standard in the assessment of bone fracture risk, to date, its association with bone fracture risk in the general post-transplant population is not robust. Therefore, randomized controlled trials with bone fracture as the primary end point are crucial. The development of noninvasive bone markers in distinguishing bone turnover and bone mineralization status is also pivotal since skeletal lesions are heterogeneous in various organ transplantations. The elucidation of these underlying skeletal lesions is necessary for the consideration of selective treatment in this population.

Post-renal transplantation hypophosphatemia

An understanding of the pathophysiologic mechanisms of post-renal transplant (PRT) bone disease is of important clinical significance. Although bone disease occurs after all solid organ transplantation, the cumulative skeletal fracture rate remains high in PRT subjects while reaching a plateau with other transplantations. One major difference in the pathophysiology of PRT bone disease is, perhaps, due to persistent renal phosphorus (Pi) wasting. Novel phosphaturic agents have recently been suggested to participate in the development of bone disease in PRT subjects. However, it is unclear as of yet whether these factors alone or in conjunction with excess parathyroid hormone (PTH) secretion play a key role in the development of negative Pi balance and consequent bone disease in this population. In this review, I present a natural history of PRT hypophosphatemia and persistent renal Pi leak, provide pathophysiologic insight into these developments, and discuss the difficulty in diagnosing these phenotypes in both adult and pediatric populations.

Fractures and avascular necrosis before and after orthotopic liver transplantation: long-term follow-up and predictive factors

With early posttransplant bone loss, orthotopic liver transplantation (OLT) recipients experience a high rate of fracturing and some avascular necrosis (AVN), but little is known about the incidence of and predictive factors for these skeletal complications. We studied 360 consecutive patients who underwent transplantation for primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) and assessed both vertebral and nonvertebral (rib, pelvic, and femur) fractures in a protocolized fashion. Before OLT, 20% of the patients had experienced fracturing, and 1.4% of the patients had experienced AVN. Following OLT, there was a sharp increase in fracturing, with a 30% cumulative incidence of fractures at 1 year and 46% at 8 years after transplantation. In contrast to previous studies, there was a similar incidence of posttransplant vertebral and nonvertebral fractures. The greatest risk factors for posttransplant fracturing were pretransplant fracturing and the severity of osteopenia and posttransplant glucocorticoids. Nine percent of the liver recipients experienced AVN after OLT, and this correlated with pretransplant and posttransplant lipid metabolism, bone disease (bone mineral density and fracturing), and posttransplant glucocorticoids. A novel association between cholestasis and AVN was also identified, the mechanism for which is not known.

CONCLUSION

Fortunately, recent years have seen an increase in the bone mass of liver recipients and, along with this, less fracturing and less AVN. Nonetheless, 25% of patients undergoing OLT for chronic cholestatic liver disease still develop de novo fractures after OLT; this situation demands an ongoing search for effective therapeutic agents for these patients.

Review article: medical management of the liver transplant recipient - a primer for non-transplant doctors

BACKGROUND

Survival 10 years after orthotopic liver transplantation now approaches 65%. Consequently, community doctors must manage the metabolic and neoplastic complications of orthotopic liver transplantation in an ageing population.

AIMS

To review common sources of morbidity and mortality in long-term orthotopic liver transplantation recipients, and to make evidence-based recommendations regarding their management.

METHODS

Pertinent studies and reviews were identified by literature search through PubMed. Where evidence-based recommendations could not be gleaned from the literature, expert opinion was obtained from syllabi of national meetings.

RESULTS

The two most common causes of morbidity and mortality in orthotopic liver transplantation recipients are atherosclerotic vascular disease and de novo malignancy. The pathogenesis of many complications begins before orthotopic liver transplantation, and many are potentially modifiable. Most complications, however, can be directly ascribed to immunosuppressive agents. Despite improvements in our understanding of the pathogenesis and epidemiology of the metabolic and neoplastic complications of orthotopic liver transplantation, remarkably few randomized-controlled studies exist to define their optimal management.

CONCLUSIONS

Orthotopic liver transplantation recipients experience and succumb to the same afflictions of old age as non-transplant patients, but with greater frequency and at an earlier age. Most recommendations regarding surveillance for, and treatment of, medical complications of orthotopic liver transplantation remain based upon expert opinion rather than evidence-based medicine.

Bone mineral density before and after OLT: long-term follow-up and predictive factors

Fracturing after liver transplantation (OLT) occurs due to the combination of preexisting low bone mineral density (BMD) and early posttransplant bone loss, the risk factors for which are poorly defined. The prevalence and predictive factors for hepatic osteopenia and osteoporosis, posttransplant bone loss, and subsequent bone gain were studied by the long-term posttransplant follow-up of 360 consecutive adult patients with end-stage primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Only 20% of patients with advanced PBC or PSC have normal bone mass. Risk factors for low spinal BMD are low body mass index, older age, postmenopausal status, muscle wasting, high alkaline phosphatase and low serum albumin. A high rate of spinal bone loss occurred in the first 4 posttransplant months (annual rate of 16%) especially in those with younger age, PSC, higher pretransplant bone density, no inflammatory bowel disease, shorter duration of liver disease, current smoking, and ongoing cholestasis at 4 months. Factors favoring spinal bone gain from 4 to 24 months after transplantation were lower baseline and/or 4-month bone density, premenopausal status, lower cumulative glucocorticoids, no ongoing cholestasis, and higher levels of vitamin D and parathyroid hormone. Bone mass therefore improves most in patients with lowest pretransplant BMD who undergo successful transplantation with normal hepatic function and improved gonadal and nutritional status. Patients transplanted most recently have improved bone mass before OLT, and although bone loss still occurs early after OLT, these patients also have a greater recovery in BMD over the years following OLT.

Post-renal transplantation hypophosphatemia: a review and novel insights

PURPOSE OF REVIEW

This review intends to elucidate the pathophysiologic mechanism of renal phosphorus loss in the post-renal transplantation population. This review will provide new insight in to the pathophysiologic mechanism(s) responsible for the development of this phenomenon and will also explore the pathogenetic role of persistent phosphorus wasting in the development of post-renal transplantation osteodystrophy.

RECENT FINDINGS

Recently, the phosphaturic hormone, fibroblast growth factor-23, has been ascertain to be increased in the sera of patients with chronic kidney and end-stage renal disease. There is new evidence that a non-PTH humoral factor is persistently present in post-renal transplantation patients that is likely responsible for the observed persistent renal phosphorus loss. We offer that fibroblast growth factor-23 (and/or other phosphatonins) is the culprit factor responsible for the phenomenon of persistent hypophosphatemia in post-renal transplantation patients. Moreover, we believe that the phenomenon of persistent renal phosphorus wasting is an important but overlooked cause of osteodystrophy and increased fracture risk in this patient population.

SUMMARY

The pathophysiology of post-renal transplantation phosphorus wasting is complex and to date is still not fully recognized. Further studies of the regulatory mechanism of fibroblast growth factor-23 and its metabolism may offer additional insights into phosphorus homeostasis and its clinical application in the post-renal transplantation population.

Bone Mineral Density in Adults Transplanted in Childhood for Liver Disease

INTRODUCTION

It remains unclear whether bone mineral density (BMD) is compromised in adult life after liver transplantation (LT) during childhood.

METHODS

This was a cross-sectional study of total body (TB) and lumbar spine (LS) dual-energy X-ray absorptiometry, anthropometry, and data collected, which included a physical activity questionnaire.

RESULTS

Fifteen patients were enrolled. Mean age at LT was 10.6 (4.5) years (range 1.6 to 18.4). The mean posttransplant period was 12.0 (4.1) years (range 4.4 to 16.7); six were men. The mean TB BMD, 1.11 (0.12) g/cm2, was similar to LS BMD, 1.15 (0.17) g/cm2 (P=.82). The Z-score mean was lower for TB BMD, -0.92 (1.2), and LS BMD, -0.41 (1.2) (P=.22). There was no effect from gender, pretransplant cholestasis (9/15 cases), age at LT, and time since LT. BMD (Z-score) was better for those on corticosteroids (9/15 cases): TB BMD -0.42 (1.20) versus -1.77 (0.86) (P=.04); LS BMD 0.14 (1.00) versus -1.54 (1.03) (P=.03). Anthropometry Z-scores were height -0.04 (0.70), weight -0.33 (0.39), and BMI -0.32 (0.37). There was no correlation between Z-scores for BMD and any of the anthropometry parameters.

CONCLUSION

Although the mean TB BMD was lower in transplanted patients than would be expected for the general population, overall BMD and anthropometry were with the normal adult ranges for adults who had undergone LT in childhood.

The Prevention of Bone Fractures After Liver Transplantation: Experience With Alendronate Treatment

OBJECTIVE

The aim of this study was to prevent fractures in the first postoperative year.

METHODS AND PATIENTS

We studied 59 patients (48 men, 11 women) aged 42.6+/-11.4 years, who underwent liver transplantation. All patients received oral alendronate 70 mg weekly and calcium 1 g and calcitriol 0.5 mug daily. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry at the lumbar spine and proximal femur at baseline as well as at 6 and 12 months after transplantation for comparison with an historical control group (n=31). Spinal radiographs were obtained to assess vertebral fractures at the same time. Additionally, serum osteocalcin, serum parathyroid hormone (PTH), urinary deoxypyridinoline (DPD), and biochemical parameters were determined every 3 months.

RESULTS

At baseline, femoral total BMD of men was significantly greater than that of women (P<.05, .85+/-.1 vs .74+/-.1). A significant increase in BMD was observed at 12 months (P<.05), no patient developed a bone fracture. Comparison analysis of genders showed that there was a significant difference in favor of men (P<.05). The lumbar BMD, neck T-, and Z-scores were significantly higher among patients treated with alendronate than historical controls (P<.05). After 3 months, serum PTH was increased and serum osteocalcin and urinary DPD were reduced. No severe side effects from alendronate treatment were observed during the study.

CONCLUSION

A direct sign of the success of our study was no fracture observed during the first postoperative year. Alendronate should be considered for patients with low bone mass after liver transplantation.

Effects of alendronate on bone mineral density and bone metabolic markers in patients with liver transplantation

INTRODUCTION

The purpose of this study was to evaluate the effects of alendronate (ALN) on bone mineral density (BMD) and bone turnover markers in patients with orthotopic liver transplantation (OLT).

METHODS

In the prospective, controlled, open study with 24 months of follow-up, 98 patients with OLT were randomised to receive ALN 70 mg weekly or no ALN; calcium (Ca) 1,000 mg daily and 0.5 mcg calcitriol daily were provided to all patients. Lumbar spine (LS) and hip BMDs were measured at 6-month intervals by dual-energy X-ray absorptiometry (DEXA). Spinal radiographs were obtained to assess vertebral fractures. Additionally, bone turnover markers, serum parathyroid hormone (PTH) and biochemical parameters were determined every 3 months.

RESULTS

Compared with the control group, the ALN group showed significant increases in BMD of the LS (5.1+/-3.9% vs 0.4+/-4.2%, p<0.05 at 12 months, 8.9+/-5.7% vs 1.4+/-4.9%, p<0.05 at 24 months), femoral neck (4.3+/-3.8% vs -1.1+/-3.1%, p<0.05 at 12 months, 8.7+/-4.8% vs 0.6+/-4.5%, p<0.05 at 24 months) and total femur (3.6+/-3.8% vs -0.6+/-4.0%, p<0.05 at 12 months, 6.2+/-3.8% vs 0.3+/-4.6%, p<0.05 at 24 months). In the ALN group, osteocalcin and urinary deoxypyridinoline (DPD) decreased significantly at the sixth month, with no further change, by -35.6% and -63.0%, on average, respectively (p<0.05). In the control group, a significant increase in biochemical markers of bone turnover was observed in comparison to baseline values (p<0.05). PTH increased within reference levels without a difference between groups. Two nonvertebral fractures (4.2%) and nine vertebral fractures (18.8%) in the control group and three vertebral fractures (6.8%) in the ALN group occurred during the follow-up. The weekly ALN was well tolerated, and no severe side effects occurred.

CONCLUSION

This is the first randomised study including a control group to demonstrate that weekly ALN was able to significantly increase BMD in patients with OLT when compared with Ca and calcitriol alone. However, ALN did not appear to offer protection against fractures.

Alendronate in combination with calcium and vitamin D prevents bone loss after orthotopic liver transplantation: a prospective single-center study

Bone loss is a common complication in patients before and after liver transplantation (LT). The aim of this study was to investigate the efficacy of prophylactic treatment with bisphosphonates after LT in preventing progressive bone loss in LT patients. We included 136 patients with end-stage liver diseases awaiting LT. Bone mineral density (BMD) (by dual X-ray absorptiometry) and markers of bone metabolism were determined before, and 4, 12, 24, 36, and 48 months after LT. All patients received vitamin D and calcium supplementation before and after LT, those with osteopenia or osteoporosis prior to LT were additionally treated with alendronate following LT. Decreased BMD was seen in a high percentage of patients undergoing LT (osteopenia 48.5%, osteoporosis 23.5%). Reduced BMD before LT was not related to gender, underlying liver disease, or Child-Turcotte-Pugh classification. Body mass index (BMI) prior to LT, however, correlated significantly with the fracture risk. Alendronate prevented the ubiquitously observed bone loss after LT in patients with osteoporosis and osteopenia and, in addition, led to an increase in BMD in patients with osteoporosis within 24 months after LT. In conclusion, our study suggests that alendronate is efficacious in preventing the natural course of bone loss associated with LT.

Osteoporose após transplante de órgãos sólidos

A osteoporose é uma complicação comum após os transplantes de rim, coração, fígado e pulmão. Os esquemas imunossupressores para evitar a rejeição do órgão enxertado após o transplante freqüentemente incluem glicocorticóides, ciclosporina A e tacrolimus, os quais possuem efeitos danosos sobre a homeostase mineral óssea, impostos a um esqueleto já comprometido. Outros fatores que provavelmente contribuem para a patogênese da osteoporose pós-transplante são deficiência de vitamina D, hiperparatireoidismo secundário e hipogonadismo. Medidas para avaliação da saúde óssea antes do transplante deveriam ser realizadas: densitometria mineral óssea, radiografia da coluna, avaliação do nível de vitamina D e dos hormônios gonadais. Todos os pacientes transplantados deveriam ser submetidos à profilaxia da perda óssea. Estudos clínicos sugerem que os bisfosfonatos são os agentes mais promissores para a prevenção e o tratamento da osteoporose pós-transplante.

Secondary osteoporosis: underlying disease and the risk for glucocorticoid-induced osteoporosis

BACKGROUND

Chronic diseases of many organ systems require long-term (>or=1 year) treatment with glucocorticoids. Owing to the catabolic activity of glucocorticoid therapy, osteoporosis is a potential complication.

OBJECTIVES

This review discusses glucocorticoid-induced bone loss and the factors, including underlying disease, that increase the risk for osteoporosis. Therapeutic options for the prevention and treatment of glucocorticoid-induced osteoporosis (GIO) also are reviewed.

METHODS

A review of the English-language literature was conducted using the MEDLINE database and proceedings from scientific meetings. Search terms including glucocorticoid-induced osteoporosis, bone loss, and fracture were used to refine the search, and preference was given to studies published after 1990.

RESULTS

Long-term glucocorticoid treatment causes bone loss that is most precipitous in the first 6 months. Patients treated with glucocorticoids have additional risk factors for bone loss and osteoporosis that are associated with their primary disease. Chronic diseases can cause changes in bone metabolism, leading to bone loss in addition to that induced by glucocorticoids alone. Bone loss can be minimized through proper nutrition, weight-bearing exercise, calcium and vitamin D supplementation, and, where indicated, bisphosphonate treatment. The American College of Rheumatology Ad Hoc Committee on Glucocorticoid-Induced Osteoporosis guidelines recommend bisphosphonates for minimizing bone loss and fracture risk in patients at risk for GIO. Risedronate is indicated for the prevention and treatment of GIO, and alendronate is indicated for its treatment. Both risedronate and alendronate increase bone mineral density in patients at risk for GIO. Risedronate significantly reduces the incidence of vertebral fractures after 1 year of treatment (P<0.05). The effectiveness and tolerability of the bisphosphonates have not been established in pregnant women or pediatric patients.

CONCLUSIONS

Men and women initiating long-term glucocorticoid treatment and those with GIO should be concomitantly treated with effective osteoporosis therapy to reduce fracture risk and counseled on preventive lifestyle changes.

Disorders associated with acute rapid and severe bone loss

We describe a constellation of bone diseases characterized by the common feature of acute, rapid, and severe bone loss accompanied by dramatic fracture rates. These disorders are poorly recognized, resulting mainly from systemic diseases, frailty, immobilization, and immunosuppressive drugs, such as glucocorticoids and the calcineurin inhibitors. The opportunity to prevent or treat fractures is commonly missed because they are often not detected. Ideally, patients need to be identified early and preventative therapy initiated promptly to avoid the rapid bone loss and fractures. The most effective therapy at present seems to be the bisphosphonates, particularly when bone resorption is predominant. However, more severe forms of bone loss that result from an osteoblastic defect and reduced bone formation may benefit potentially more from newer anabolic agents, such as recombinant human parathyroid hormone (rhPTH).

Osteoporosis after liver transplantation

Osteoporosis remains a serious potential complication of liver transplantation, although its incidence may be significantly reduced by the use of lower doses of glucocorticoids. Additional factors likely to contribute to its pathogenesis include other immunosuppressive agents, particularly cyclosporin A and FK506, vitamin D insufficiency, secondary hyperparathyroidism, hypogonadism and pre-existing bone disease. Bone density assessment and spinal X-rays should be performed before transplantation to assess subsequent fracture risk and vitamin D and gonadal status assessed. Measures should be taken to optimise bone health prior to transplantation; in those with low bone mineral density and/or previous fragility fracture, prophylaxis against bone loss after transplantation should be considered. Although anti-fracture efficacy has not been established for any agent there is evidence, mainly in patients undergoing other forms of solid organ transplantation, that repeated infusions of pamidronate may be effective in preventing bone loss.

Secondary Osteoporosis in Liver Transplant Recipients: a Longitudinal Study in Patients With and Without Cholestatic Liver Disease

BACKGROUND

Metabolic bone disease is one of the major long-term complications in liver transplant recipients, but it remains unclear which patients are at highest risk for developing severe bone disease following transplantation.

METHODS

A total of 46 consecutive, adult patients with chronic liver disease accepted for a liver transplantation waiting list were prospectively included in the study. The patients were classified into two groups: group A-chronic cholestatic liver disease (n = 28), and group B-chronic non-cholestatic liver disease (n = 18). Bone mineral density (BMD) was measured at acceptance for the waiting list and at 3, 12 and 36 months following transplantation. Markers of bone turnover (serum-bone specific alkaline phosphatases (bALP), s-osteocalcin, s-l-collagen-C-terminal telopeptide (1-CTP) and urine N-terminal telopeptides u-Ntx) were measured at acceptance and at 3, 6, 12, 24 and 36 months following transplantation. BMD and markers of bone turnover were compared with similar values in a matched control group of 42 healthy individuals.

RESULTS

BMD decreased significantly during the early post-transplantation period (median bone loss femoral neck (FN) 3 months post-transplant 8.5%). BMD levels declined slightly from 3 to 12 months following transplantation and increased thereafter. The relative bone loss was greatest among group B patients (relative bone loss FN 3 months post-transplant: group A, 8% versus group B, 13%; P = 0.04). At 36 months, 8/17 group A and 2/9 group B patients had BMD levels that exceeded the pretransplant levels (P = 0.12). The early bone loss was positively correlated with an increase in resorption markers (s-1-CTP and u-Ntx). Group B had higher levels of both s-1-CTP and u-Ntx at 3 and 6 months post-transplant than group A patients (P = 0.03). Bone formation markers increased slowly from 6 months post-transplant and onwards. Relative bone loss was positively correlated to total glucocorticoid dose during the first 3 months post-transplant. There were no differences in BMD between patients receiving tacrolimus versus those receiving'cyclosporin A.

CONCLUSION

Bone loss following liver transplantation is considerable in patients with both cholestatic and non-cholestatic liver disease, the first group has the poorest starting-point while the latter group has the greatest bone loss following transplantation. Bone loss is closely correlated with biochemical markers of bone resorption and total dose of glucocorticoids given post-transplant.

Predominant factors associated with bone loss in liver transplant patients - after prolonged post-transplantation period

INTRODUCTION

Osteoporosis is a major cause of morbidity in liver transplant recipients and is associated with multiple factors.

OBJECTIVES

To evaluate bone mineral density (BMD), bone turnover and calcium-regulating hormones in 29 patients (17 men, 12 women) 2-12 yrs following liver transplantation for non-alcoholic liver diseases.

RESULTS

Fifteen patients (52%) were on immunosuppressive treatment with tacrolimus and 14 (48%) with cyclosporine. Eleven patients (38%) were currently on prednisone, 18 patients (62%) had stopped glucocorticoid treatment 6 months to 11 yrs prior to the study. Nineteen patients (65.5%) had decreased BMD according to WHO criteria, 17 (58.2%) at the femoral neck, 13 (44.8%) at the lumbar spine. Nineteen patients (65.5%) had a subnormal (<15 ng/mL) serum level of 25 (OH) D3. These patients had significantly lower BMD at the femoral neck (p = 0.02). Femoral neck BMD negatively correlated with serum parathyroid hormone level (p = 0.06, r = -0.35), length of the post-transplantation period (p = 0.025, r = -0.416) and duration of glucocorticoid treatment (p = 0.029, r = -0.406), regardless of its cumulative dose. Symptomatic fractures were less frequent in tacrolimus treated patients than in cyclosporine users (p = 0.03).

CONCLUSIONS

Decreased BMD is frequent following liver transplantation and is affected by vitamin D deficiency, cyclosporine use, and the duration of glucocorticoid therapy, but not by its cumulative dose. Achievement and maintenance of optimal vitamin D status and shortening of glucocorticoid treatment period may have a favorable effect on bone preservation.

Lack of effect of intravenous pamidronate on fracture incidence and bone mineral density after orthotopic liver transplantation

BACKGROUND/AIMS

Increased rates of bone loss and fracture have been reported after liver transplantation. The aim of this study was to investigate the effects of a pre-transplant infusion of pamidronate on fracture incidence and bone loss during the first year after transplantation.

METHODS

Ninety-nine adults awaiting orthotopic liver transplantation (OLT) were randomised to pamidronate or no treatment. Spinal X-rays were obtained at baseline and after 12 months. Bone mineral density (BMD) was measured at the lumbar spine (L1-4) and femoral neck at baseline, and 3, 6, and 12 months after OLT.

RESULTS

The incidence of fractures in the first year after OLT was 8%, four patients within the pamidronate treated group and two in the untreated group developing fractures (P=0.40). No significant spinal bone loss occurred in either group during the first year. However, significant and sustained bone loss occurred at the femoral neck in both groups. No significant differences were seen between pamidronate treated or untreated groups at either site.

CONCLUSIONS

Pamidronate in the regimen used had no significant effect on fracture rate or BMD post-transplant. The low incidence of fracture and absence of spinal bone loss indicate that bone disease after liver transplantation may be less common than previously reported.

Posttransplantation care: role of the primary care physician versus transplant center

1. Forty percent of transplant centers expect the primary care physician to be the primary physician; 40% have both a primary care physician and a hepatologist manage the patient. 2. Transplant centers expect primary care physicians to provide general preventive medicine, physical examinations, vaccinations, and, rarely, management of hypertension, renal dysfunction, and diabetes. 3. A high percentage of primary care physicians feel comfortable caring and managing the overall health care of a long-term liver transplant patient. 4. Primary care physicians feel at most ease managing preventive care, annual physical examinations, hypertension, diabetes mellitus, hyperlipidemia, bone disease, and vaccinations. 5. Primary care physicians should be aware of the common medical conditions of the liver transplant patient of hypertension, diabetes, obesity, hyperlipidemia, and recurrent disease. 6. Common medical conditions for both the transplant centers and primary care physicians are hypertension, dyslipidemia, diabetes mellitus, malignancy, bone disease, pregnancy, vaccination, infectious prophylaxis, and headaches.

Bone disease after liver transplantation

1. Bone disease is a common problem in patients with chronic liver disease and liver transplants. 2. The cause of bone disease in these patients is multifactorial. 3. Bone disease worsens initially after liver transplantation, with subsequent improvement over time. However, bone disease in liver transplant recipients is common with long-term follow-up. 4. Evaluation of these patients should include metabolic and hormonal evaluations in conjunction with dual energy x-ray absorptiometry or bone mineral density evaluation. 5. Treatment with calcium, vitamin D, and hormonal supplements should be considered when appropriate for patients awaiting and after liver transplantation. The use of bisphosphanates and calcitonin also should be considered, although published studies in these populations are few in number.

Nutritional and metabolic issues in cirrhosis and liver transplantation

In the last year some relevant papers on nutrition and metabolism in chronic liver disease and transplantation have been published. Studies investigating the reliability of predicting energy expenditure in cirrhosis, and some relevant contributions to the understanding of metabolic consequences of liver transplantation, deserve particular mention. These include the first direct evidence that liver transplantation corrects the insulin resistance present in cirrhosis, as well as studies on the role of genetic polymorphism of the vitamin D receptor gene in bone loss after transplantation. Other papers have dealt with body composition, polyunsaturated fatty acid and antioxidant status in cirrhosis. However, relevant contributions in the field of nutritional support in cirrhosis are surprisingly lacking.

Management of osteoporosis in primary biliary cirrhosis

Osteoporosis is not a significant problem in the majority of patients with primary biliary cirrhosis (PBC). However, substantial bone-related morbidity may occur in patients with advanced disease, in particular after liver transplantation. The cause of osteoporosis in PBC is multifactorial, and pathophysiological mechanisms specifically related to PBC have not been defined. In general, the principles of management followed in post-menopausal osteoporosis also apply in chronic liver disease. Dual energy X-ray absorptiometry is currently the method of choice for monitoring bone mineral density. Avoidance of conditions with potential negative effects on bone mass, and maintaining adequate serum vitamin D levels and calcium intake form the cornerstone in preventing osteoporosis. Bisphosphonates are the most logical choice when specific medical treatment of PBC-associated osteoporosis is indicated, as well as for preventing bone loss during glucocorticoid treatment and after liver transplantation. Recent studies suggest that active vitamin D analogues are effective alternatives in the post-transplant setting.