Osteoporosis after renal transplantation

Bone Effect and Safety of One-Year Denosumab Therapy in a Cohort of Renal Transplanted Patients: An Observational Monocentric Study

In 32-kidney transplanted patients (KTxps), the safety and the effects on BMD and mineral metabolism (MM) of one-year treatment with denosumab (DB) were studied. Femoral and vertebral BMD and T-score, FRAX score and vertebral fractures (sVF) before (T0) and after 12 months (T12) of treatment were measured. MM, renal parameters, hypocalcemic episodes (HpCa), urinary tract infections (UTI), major graft and KTxps outcomes were monitored. The cohort was composed mainly of females, n = 21. We had 29 KTxps on steroid therapy and 22 KTxps on vitamin D supplementation. At T0, 25 and 7 KTxps had femoral osteoporosis (F-OPS) and osteopenia (F-OPS), respectively. Twenty-three and six KTxps had vertebral osteoporosis (V-OPS) and osteopenia (V-OPS), respectively. Seventeen KTxps had sVF. At T12, T-score increased at femoral and vertebral sites (p = 0.05, p = 0.008). The prevalence of F-OPS and V-OPS reduced from 78% to 69% and from 72% to 50%, respectively. Twenty-five KTxps ameliorated FRAX score and two KTxps had novel sVF. At T12, a slight reduction of Ca was present, without HpCa. Four KTxps had UTI. No graft rejections, loss of graft or deaths were reported. Our preliminary results show a good efficacy and safety of DB in KTxps. Longer and randomized studies involving more KTxps might elucidate the possible primary role of DB in the treatment of bone disorders in KTxps.

Vitamin D receptor polymorphisms and bone health after kidney transplantation

Background/aim

Bone disease is one of the most prominent complications after kidney transplantation. Bone diseases include osteoporosis, persistent secondary hyperparathyroidism, and avascular necrosis (AVN). We investigated the relationship between the polymorphisms of the vitamin D receptor (VDR) gene and bone diseases occurring after kidney transplantation.

Materials and methods

The study consists of 234 kidney allograft recipients with a minimum follow-up of five years after kidney transplantation. Patients with glomerular filtration rates less than 30 mL/min/1.73m2, a history of parathyroidectomy, bisphosphonate use pre- or post-transplantation, and cinacalcet use posttransplantation excluded. We evaluated associations between the polymorphisms of the VDR gene (BsmI, TaqI, ApaI, FokI, and Cdx2), the first-year bone mineral density (BMD) scores, persistent secondary hyperparathyroidism, and AVN.

Results

Patients with low BMD scores were significantly younger (P = 0.03) and had higher intact parathormone (iPTH) levels (P = 0.03). Cdx2 TT genotype significantly increases the risk of low BMD scores (OR: 3.34, P = 0.04). Higher phosphate levels were protective against abnormal BMD scores (OR: 0.53; P = 0.03). Patients with persistent hyperparathyroidism had significantly longer dialysis vintage and higher pretransplantation iPTH levels (P = 0.02 and P < 0.001, respectively). Cdx2, CT/TT, and ApaI CA/AA genotypes significantly increase the risk of persistent hyperparathyroidism (OR: 6.81, P < 0.001, OR: 23.32, P < 0.001, OR:4.01, P = 0.02, and OR: 6.30, P = 0.01; respectively). BsmI CT/TT genotypes were found to increase AVN risk with an HR of 3.48 (P = 0.03). Higher hemoglobin levels were also found to decrease AVN risk with an HR of 0.76 (P = 0.05).

Conclusion

Certain VDR gene polymorphisms are associated with a higher risk for bone diseases after kidney transplantation.

Expression of Circulating MicroRNAs Linked to Bone Metabolism in Chronic Kidney Disease-Mineral and Bone Disorder

The pathophysiology of chronic kidney disease-mineral and bone disorder (CKD-MBD) is complex and multifactorial. Recent studies have identified a link between microRNAs (miRNAs) and bone loss. In this study, we investigated the expression of miRNAs in CKD-MBD. In this case-control study, we included thirty patients with CKD-MBD (cases) and 30 age- and gender-matched healthy individuals (controls). Bone mineral density (BMD) and trabecular bone score (TBS) evaluation was performed with dual X-ray absorptiometry. The selected panel of miRNAs included: hsa-miRNA-21-5p; hsa-miRNA-23a-3p; hsa-miRNA-24-2-5p; hsa-miRNA-26a-5p; hsa-miRNA-29a-3; hsa-miRNA-124-3p; hsa-miRNA-2861. The majority of cases had low BMD values. The relative expression of miRNA-21-5p was 15 times lower [fold regulation (FR): -14.7 ± 8.1, p = 0.034), miRNA-124-3p, 6 times lower (FR: -5.9 ± 4, p = 0.005), and miRNA-23a-3p, 4 times lower (FR: -3.8 ± 2.0, p = 0.036) in cases compared to controls. MiRNA-23a-3p was significantly and inversely correlated with TBS, adjusted for calcium metabolism and BMD values (beta = -0.221, p = 0.003, 95% CI -0.360, -0,081) in cases. In a receiver operating characteristic (ROC) analysis, expression of miRNA-124-3p demonstrated 78% sensitivity and 83% specificity in identifying CKD patents with osteoporosis. Serum expression of miRNAs related to osteoblasts (miRNA-23a-3p) and osteoclasts (miRNA-21-5p, miRNA-124-3p) is significantly altered in patients with CKD-MBD.

Lactobacillus Fermentum ZS40 prevents secondary osteoporosis in Wistar Rat

Using retinoic acid to inducer, we successfully established a rat model of secondary osteoporosis and verified the preventive effect of Lactobacillus fermentum ZS40 (ZS40) on secondary osteoporosis. Serum biochemical indicators showed that ZS40 can effectively slow down bone resorption caused by retinoic acid, increase blood content of calcium, phosphorus, bone alkaline phosphatase, bone gla protein, and insulin-like growth factor 1, and decrease blood content of tartrate-resistant acid phosphatase (TRAP) 5b. qRT-PCR results showed that ZS40 could upregulate mRNA expressions of β-catenin, Wnt10b, Lrp5, Lrp6, Runx2, ALP, RANKL, and OPG, and downregulate mRNA expression of DKK1, RANK, TRACP, and CTSK in the rats' spinal cord. Results following TRAP staining showed that ZS40 could slow down retinoic acid-induced formation of osteoclasts. Micro-CT results showed that ZS40 could reduce Tb.Sp, increase BV/TV, Tb.N, Tb.Th, and ultimately increase bone mineral density of rats in vivo. These findings indicate that ZS40 might have a potential role in preventing retinoic acid-induced secondary osteoporosis in vivo.

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.

Charcot Neuroarthropathy Advances: Understanding Pathogenesis and Medical and Surgical Management

Understanding new theories of the epidemiology of Charcot neuroarthropathy is practice changing. Treatment of Charcot neuroarthropathy is evolving from a passive approach to one that sees the urgency of proactive, early recognition, thereby avoiding the cascading events that lead to the complex, limb-threatening deformities. Preventive medicine is the most efficient at avoiding severe deformity, with prolonged offloading and immobilization as the current mainstay of treatment. However, with recent advancements in medical and surgical modalities, this may become the treatment of the past as clinicians begin to favor medical management and early surgical intervention.

Relationship Between Osteoporosis and Serum Sclerostin Levels in Kidney Transplant Recipients

OBJECTIVES

Sclerostin, a peptide secreted primarily by osteocytes, suppresses osteoblast maturation, thus reducing bone formation. Here, we evaluated the relationship between sclerostin levels and osteoporosis in kidney transplant recipients.

MATERIALS AND METHODS

This cross-sectional study included 78 kidney transplantrecipients > 18 years old and at least 6 months posttransplant. In our center, unrelated living-donor kidney transplants are not performed. Patients with parathyroid adenoma or parathyroidectomy history were excluded. Lumbar and femoral neck bone mineral densities andT and Z scores were obtained by dual-energy X-ray absorptiometry; results were used to divide patients into osteoporotic and nonosteoporotic groups. Serum sclerostin was measured by enzyme-linked immunosorbent assay.

RESULTS

: Of total patients, 43% had osteoporosis, mean age was 40.8 years, and 70% were male. Groups had similar ages, male-female distribution, time posttransplant, cumulative corticosteroid dose, estimated glomerular filtration rates, and 25-hydroxyvitamin D2 levels (P > .05). The osteoporotic group had lower sclerostin (405.9 ± 234.9 vs 521.7 ± 233.5 ng/dL; P = .035) and higherintact parathyroid hormone levels (110.9 ± 68.0 vs 84.8 ± 41.4 pg/mL; P = .04) than the nonosteoporotic group. Sclerostin levels were not correlated with cumulative corticosteroid dose, intact parathyroid hormone, bone mineral density, and T scores at any site but were weakly negatively correlated with age (P = .04, r = -0.25). In multiple regression analyses, only intact parathyroid hormone had negative effects on lumbar bone mineral density (P = .02) andT scores (P = .036). Serum sclerostin levels, age, and cumulative corticosteroid dose did not affect lumbar or hip bone mineral density and T scores (P > .05).

CONCLUSIONS

Sclerostin levels were low in our osteoporotic patients;therefore, sclerostin may not be a contributing factor to osteoporosis development. Because sclerostin is an osteocyte-derived peptide, its serum levels only reflect total osteocyte number and bone mass.

Development of Charcot Neuroarthropathy in Diabetic Patients who Received Kidney or Kidney-Pancreas Transplants

Only a small percentage of the general diabetic population develops Charcot neuroarthropathy. Charcot arthropathy greatly increases the risk of foot complications. At our academic institution, there appeared to be an increased incidence of Charcot arthropathy in transplant patients. We hypothesized that Charcot neuroarthropathy incidence is higher in the diabetic patients who had received kidney or kidney-pancreas transplants. The charts of 1000 patients were reviewed from January 2000 to January 2011. Four hundred and eighty-seven patients were included in the study. Of these diabetic patients, 249 had received a kidney transplant and 238 a kidney-pancreas transplant. The data were analyzed for the incidence of Charcot in each group. Other risk factors and sequelae were also evaluated and analyzed. The incidence of Charcot development in the diabetic patients who had a kidney-pancreas transplant was 18.4%, 44 of 238 patients. This was significantly higher than the incidence in kidney transplant patients, which was 11.2%, 28 of 249 patients (p < .05). Peripheral arterial disease was a statistically significant independent risk factor for developing ulceration, osteomyelitis, and subsequent amputation. Type 1 diabetic patients developed Charcot at a higher rate that was also statistically significant compared with type 2 diabetic patients. In our study, diabetic patients who had undergone kidney-pancreas transplants were associated with higher risk for development of Charcot neuroarthropathy than kidney transplants alone. The incidence of Charcot development in both these transplant groups was also much higher than in the general diabetic population. This is of particular interest to clinicians and surgeons as both transplant groups were found to be high risk for subsequent foot ulceration, infection, and amputation.

Effects of denosumab on bone metabolism and bone mineral density in kidney transplant patients: a systematic review and meta-analysis

OBJECTIVE

The use of immunosuppressive agents, especially glucocorticoids, are associated with increased risks of bone loss in kidney transplant patients. Denosumab, a potent antiresorptive agent, has been shown to increase bone mineral density (BMD) in patients with CKD. However, its effects on bone metabolism and BMD in kidney transplant patients remain unclear.

METHODS

A literature search was conducted using MEDLINE, EMBASE, and Cochrane Database from inception through April 2018 to identify studies evaluating denosumab's effect on changes in bone metabolism and BMD from baseline to post-treatment course in kidney transplant patients. Study results were pooled and analyzed utilizing random-effects model. The protocol for this systematic review is registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42018095055).

RESULTS

Five studies (a clinical trial and four cohort studies) with a total of 162 kidney transplant patients were identified. The majority of patients had a baseline eGFR ≥ 30 mL/min/1.73 m². After treatment (≥ 6 to 12 months), there were significant increases in BMD with standardized mean differences (SMDs) of 3.26 (95% CI 0.88-5.64) and 1.83 (95% CI 0.43 to 3.22) for lumbar spine and femoral neck, respectively. There were also significant increases in T scores with SMDs of 0.92 (95% CI 0.58 to 1.25) and 1.14 (95% CI 0.17 to 2.10) for lumbar spine and femoral neck, respectively. After treatment, there were no significant changes in serum calcium (Ca) or parathyroid hormone (PTH) from baseline to post-treatment course (≥ 6 months) with mean differences (MDs) of 0.52 (95% CI, - 0.13 to 1.16) mmol/L and - 13.24 (95% CI, - 43.85 to 17.37) ng/L, respectively. The clinical trial data demonstrated more asymptomatic hypocalcemia in the denosumab (12 episodes in 39 patients) than in the control (1 episode in 42 patients) group. From the cohort studies, the pooled incidence of hypocalcemia following denosumab treatment was 1.7% (95% CI 0.4 to 6.6%). All reported hypocalcemic episodes were mild and asymptomatic, but the majority of patients required Ca and vitamin D supplements.

CONCLUSION

Among kidney transplant patients with good allograft function, denosumab effectively increases BMD and T scores in the lumbar spine and femur neck. From baseline to post-treatment, there are no differences in serum Ca and PTH. However, mild hypocalcemia can occur following denosumab treatment, requiring monitoring and titration of Ca and vitamin D supplements.

Recipient rs1045642 Polymorphism Is Associated With Office Blood Pressure at 1-Year Post Kidney Transplantation: A Single Center Pharmacogenetic Cohort Pilot Study

Background: Corticosteroids are associated with reduced bone mineral density (BMD), as well as water and salt retention, leading to hypertension. They are substrates for P-glycoprotein, a protein coded by the highly polymorphic ABCB1 gene. We hypothesized that one ABCB1 polymorphism, rs1045642, is associated with blood pressure and BMD parameters at 1-year post kidney transplantation (KT).

Methods: Rs1045642 was genotyped using pyrosequencing in 40 KT recipients. Both dominant (CC vs. CT + TT) and codominant (CC vs. CT vs. TT) genetic models (analysis of variance from linear regressions) were adjusted for confounding variables (age, sex, type of nephropathy, glomerular filtration rate, and corticosteroid use at 1 year).

Results: Rs1045642 genotypes were significantly associated with systolic (SBP) and diastolic (DBP) blood pressure 1-year post-transplantation, independent of the genetic model used (adjusted codominant model: SBP p-value = 0.015, DBP p-value = 0.038; adjusted dominant model: SBP p-value = 0.003, DBP p-value = 0.011). A non-statistically significant trend was observed for an association between rs1045642 and BMD change at 1-year post-KT.

Conclusions: Rs1045642 is significantly associated with higher BP 1 year after KT. Further investigations are necessary to confirm the role of rs1045642 in corticosteroid-related adverse effects.

Osteoporosis Therapy With Denosumab in Organ Transplant Recipients

OBJECTIVE

Osteoporosis and fragility fractures represent serious complications for the solid organ transplant population. The recommended osteoporosis therapy for organ recipients involves supplementation with calcium and vitamin D and bisphosphonate administration. However, these options can prove limited for patients with impaired renal function. An alternative therapy option is offered by denosumab, a monoclonal antibody that targets receptor activator of nuclear factor kappa-B ligand.

PATIENTS AND METHODS

We evaluated 63 patients with osteoporosis (23 males and 40 females, age 56.4 ± 13.1 years) following solid organ transplantation (15 diabetic patients after simultaneous transplantation of the kidney and pancreas, 34 patients after kidney transplantation, and 14 patients with liver grafts). Osteoporosis was diagnosed according to standard DEXA examination using the Lunar Prodigy apparatus. Transplanted patients with impaired renal function were treated for osteoporosis of the lumbar spine (L-spine) and/or proximal femur with calcium and vitamin D supplementation and 60 mg of denosumab every 6 months between the years 2012 and 2017. The mean duration of the therapy was 1.65 ± 0.7 years.

RESULTS

After denosumab therapy, L-spine T-scores improved across the whole group, ranging from -2.7 ± 0.09 to -1.8 ± 1.0 (p < 0.001). T-score values for the proximal femur increased from -2.5 ± 0.8 to -2.0 ± 0.7 after the therapy (p < 0.01). We observed only a mild, statistically insignificant improvement in distal forearm T-scores. The mean increase in L-spine bone mineral density (BMD) was 11.5 ± 6.2% in subjects with osteoporosis at this site and 10.4 ± 6.1% in the case of all patients. BMD of the proximal femur increased by 10.4 ± 8.3% in patients with osteoporosis and by 7.5 ± 7.3% in all patients. Denosumab therapy decreased the prevalence of osteoporosis in the L-spine from 75 to 27% (p < 0.001) and proximal femur osteoporosis from 54 to 36% (p < 0.05). Denosumab therapy reduced elevated levels of osteocalcin and beta-crosslaps (βCTX) in comparison with baseline levels (p < 0.001) across the whole group of graft recipients.

CONCLUSION

Denosumab therapy was well-tolerated and improved bone density in our group of solid organ transplant recipients. The indications are that denosumab could be a viable therapeutic option for transplanted patients with osteoporosis, especially in those with renal function impairment or bisphosphonate intolerance.

Bone Quality Assessment as Measured by Trabecular Bone Score in Patients With End-Stage Renal Disease on Dialysis

Patients with end-stage renal disease (ESRD) on maintenance hemodialysis (HD) exhibit osteoporosis and increased fracture risk. Dual-energy X-ray absorptiometry scan measurements and calculation of fracture risk assessment toll score underestimate fracture risk in these patients and do not estimate bone quality. Trabecular bone score (TBS) has been recently proposed as an indirect measure of bone microarchitecture. In this study, we investigated alterations of bone quality in patients with ESRD on HD, using TBS. Fifty patients with ESRD on HD, with a mean age 62 years, and 52 healthy individuals matched for age, body mass index, and gender, were enrolled. All participants had a bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry scan at the lumbar spine, femoral neck, total hip, and 1/3 radius. TBS was evaluated using TBS iNsight. Serum fetuin-A and plasma fibroblast growth factor-23 (FGF-23) (C-terminal) were also measured. Patients on dialysis had significantly lower BMD values at all skeletal sites measured. Plasma FGF-23 levels significantly increased and serum fetuin-Α significantly decreased in patients on dialysis compared with controls. TBS was significantly reduced in patients on dialysis compared with controls (1.11 ± 0.16 vs 1.30 ± 0.13, p < 0.001, respectively) independently of age; BMD; duration of dialysis; and serum levels of alkaline phosphatase, 25-OH-vitamin D, parathyroid hormone, fetuin-A, or plasma FGF-23. Patients on HD who were diagnosed with an osteoporotic vertebral fracture had numerically lower TBS values, albeit without reaching statistical significance, compared with patients on dialysis without a fracture (1.044 ± 0.151 vs 1.124 ± 0.173, respectively, p = 0.079). Bone microarchitecture, as assessed by TBS, is significantly altered in ESRD on patients on HD independently of BMD values and metabolic changes that reflect chronic kidney disease-mineral and bone disorder.

Osteoporosis in patients with diabetes after kidney transplantation

Preexisting diabetes increases risk of fractures after kidney transplantation (KT). However, little is known about mechanisms and prevention of increased fragility in these patients. Pathophysiology of osteoporosis after KT is complex and characterized by high prevalence of adynamic bone disease. Despite high prevalence of preexisting diabetes in KT recipients, diabetes patients were underrepresented in the studies that explored mechanisms and treatments of osteoporosis after KT. Therefore, caution should be exercised before considering conventional fracture prevention strategies in this unique group of patients. Many traditional osteoporosis medications reduce bone turnover and, hence, can be ineffective or even harmful in diabetic patients after KT. Contrary to predictions, evidence from the studies conducted in mostly non-diabetic subjects demonstrated that bisphosphonates failed to reduce fracture rates after KT. Therefore, bisphosphonates use should be limited in diabetic patients until more evidence supporting their post-transplant efficacy is available. We recommend the following strategies that may help reduce fracture risk in diabetes subjects after KT such as adequate management of calcium, parathyroid hormone, and vitamin D levels, optimization of glycemic control, use of steroid-sparing immunosuppressive regimens, and fall prevention.

1-Alpha, 25-dihydroxyvitamin D3 alters the pharmacokinetics of mycophenolic acid in renal transplant recipients by regulating two extrahepatic UDP-glucuronosyltransferases 1A8 and 1A10

Mycophenolic acid (MPA) is an important immunosuppressant broadly used in renal transplantation. However, the large inter-patient variability in mycophenolic acid (MPA) pharmacokinetics (PK) limits its use. We hypothesize that extrahepatic metabolism of MPA may have significant impact on MPA PK variability. Two intestinal UDP-glucuronosyltransferases 1A8 and 1A10 plays critical role in MPA metabolism. Both in silico and previous genome-wide analyses suggested that vitamin D (VD) may regulate intestinal UGT1A expression. We validated the VD response elements (VDREs) across the UGT1A locus with chromatin immunoprecipitation (ChIP) and luciferase reporter assays. The impact of 1-alpha,25-dihydroxyvitamin D3 (D3) on UGT1A8 and UGT1A10 transcription and on MPA glucuronidation was tested in human intestinal cell lines LS180, Caco-2 and HCT-116. The correlation between transcription levels of VD receptor (VDR) and the two UGT genes were examined in human normal colorectal tissue samples (n = 73). PK alterations of MPA following the parent drug, mycophenolate mofetil (MMF), and D3 treatment was assessed among renal transplant recipients (n = 10). Our ChIP assay validate three VDREs which were further demonstrated as transcriptional enhancers with the luciferase assays. D3 treatment significantly increased transcription of both UGT genes as well as MPA glucuronidation in cells. The VDR mRNA level was highly correlated with that of both UGT1A8 and UGT1A10 in human colorectal tissue. D3 treatment in patients led to about 40% reduction in both AUC_0-12 and Cmax while over 70% elevation of total clearance of MPA. Our study suggested a significant regulatory role of VD on MPA metabolism and PK via modulating extrahepatic UGT activity.

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.

Ibandronate in stable renal transplant recipients with low bone mineral density on long-term follow-up

BACKGROUND

Bone mineral density (BMD) has been reported to increase without specific treatment in long-term renal transplant recipients. The aim of this study was to evaluate the effect of ibandronate on BMD and kidney function in long-term renal transplant recipients as compared to a control group. Furthermore, we searched for a gender-specific treatment effect of ibandronate on BMD.

METHODS

In a retrospective, matched case-control study 60 stable renal transplant recipients were included on long-term follow-up. The patient cohort was divided into two groups. The control group (n = 30) comprised patients with close-to-normal bone mineral density who did not receive ibandronate treatment and the treatment group (n = 30) comprised patients with reduced bone mineral density who received ibandronate treatment. The groups were matched for sex, age at the time of renal transplantation, use of steroids, renal transplant function and time lag between the dual-energy X-ray absorptiometry (DEXA) measurements and renal transplantation. Patients of the treatment group were treated with 12.0 ± 6.7 g ibandronate. Treatment cycles lasted 19.3 ± 11.0 months. The first bone mineral density testing was performed 55.3 ± 60.2 months after renal transplantation followed by a second measurement 26.8 ± 12.1 months later.

RESULTS

Both groups did not differ in absolute (g/cm(2)) or relative (%) changes in BMD at the lumbar spine (0.033 ± 0.079 vs. 0.055 ± 0.066 g/cm(2), p = 0.217 and 3.6 ± 7.8 vs. 6.4 ± 8.1 %, p = 0.124) or femoral neck (0.013 ± 0.106 vs. 0.025 ± 0.077 g/cm(2), p = 0.647 and 3.2 ± 13.6 vs. 5.0 ± 13.1 %, p = 0.544) over the study period. There was no correlation of ibandronate dosages with changes in BMD (LS: r = -0.089; p = 0.639 and FN: r =+0.288; p = 0.445). We could neither determine a negative effect of ibandronate on renal transplant function over the study period, estimated via the CKD-EPI formula (-2.9 ± 7.6 vs. -2.7 ± 10.6 mL/min/1.73 m(2), p = 0.900) nor a gender-specific action of ibandronate on bone mass changes.

CONCLUSIONS

Ibandronate treatment was safe with respect to renal transplant function but did not result in a significant additive improvement in bone mineral density as compared to the untreated control group. A gender-specific action of ibandronate on BMD at the LS or FN could not be determined either.

Mechanism and Treatment Strategy of Osteoporosis after Transplantation

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