Musculoskeletal complications after renal transplantation: pathogenesis and treatment

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.

Prevalence of Musculoskeletal Manifestations in Adult Kidney Transplant's Recipients: A Systematic Review

Background and Objectives: The musculoskeletal (MSK) manifestations in the kidney transplant recipient (KTxR) could lead to decreased quality of life and increased morbidity and mortality. However, the prevalence of these MSK manifestations is still not well-recognized. This review aimed to investigate the prevalence and outcomes of MSK manifestations in KTxR in the last two decades. Materials and Methods: Research was performed in EBSCO, EMBASE, CINAHL, PubMed/MEDLINE, Cochrane, Google Scholar, PsycINFO, Scopus, Science Direct, and Web of Science electronic databases were searched during the years 2000–2020. Results: The PRISMA flow diagram revealed the search procedure and that 502 articles were retrieved from the initial search and a total of 26 articles were included for the final report in this review. Twelve studies reported bone loss, seven studies reported a bone pain syndrome (BPS) or cyclosporine-induced pain syndrome (CIPS), and seven studies reported hyperuricemia (HU) and gout. The prevalence of MSK manifestations in this review reported as follow: BPS/CIPS ranged from 0.82% to 20.7%, while bone loss ranged from 14% to 88%, and the prevalence of gout reported in three studies as 7.6%, 8.0%, and 22.37%, while HU ranged from 38% to 44.2%. Conclusions: The post-transplantation period is associated with profound MSK abnormalities of mineral metabolism and bone loss mainly caused by corticosteroid therapy, which confer an increased fracture risk. Cyclosporine (CyA) and tacrolimus were responsible for CIPS, while HU or gout was attributable to CyA. Late diagnosis or treatment of post-transplant bone disease is associated with lower quality of life among recipients

Efficacy of weekly administration of cholecalciferol on parathyroid hormone in stable kidney-transplanted patients with CKD stage 1-3

Objectives

Kidney transplant (KTx) recipients frequently have deficient or insufficient levels of serum vitamin D. Few studies have investigated the effect of cholecalciferol in these patients. We evaluated the efficacy of weekly cholecalciferol administration on parathyroid hormone (PTH) levels in stable KTx patients with chronic kidney disease stage 1-3.

Methods

In this retrospective cohort study, 48 stable KTx recipients (37 males, 11 females, aged 52 ± 11 years and 26 months post-transplantation) were treated weekly with oral cholecalciferol (7500-8750 IU) for 12 months and compared to 44 untreated age- and gender-matched recipients. Changes in levels of PTH, 25(OH) vitamin D (25[OH]D), serum calcium, phosphate, creatinine and estimated glomerular filtration rate (eGFR) were measured at baseline, 6 and 12 months.

Results

At baseline, clinical characteristics were similar between treated and untreated patients. Considering the entire cohort, 87 (94.6%) were deficient in vitamin D and 64 (69.6%) had PTH ≥130 pg/mL. Serum calcium, phosphate, creatinine and eGFR did not differ between groups over the follow-up period. However, 25(OH)D levels were significantly higher at both 6 (63.5 vs. 30.3 nmol/L, p < 0.001) and 12 months (69.4 vs. 30 nmol/L, p < 0.001) in treated vs. untreated patients, corresponding with a significant reduction in PTH at both 6 (112 vs. 161 pg/mL) and 12 months (109 vs. 154 pg/mL) in treated vs. untreated patients, respectively (p < 0.001 for both).

Conclusions

Weekly administration of cholecalciferol can significantly and stably reduce PTH levels, without any adverse effects on serum calcium and renal function.

Mineral and Bone Disorders After Kidney Transplantation

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

Extreme hypercalcemia in a kidney transplant recipient

Post-transplant hypercalcemia is a major problem in renal transplant recipients, which may negatively affect both graft and patient survival. In this paper, we present a 66-year-old male kidney transplant recipient, who was admitted to our clinic with symptoms of fever, nausea, vomiting and lethargy. Laboratory data showed good renal function; however, a serum calcium level of 22.1 mg/dL. The patient was treated by isotonic saline together with furosemide and methylprednisolone. Because of treatment resistance, subcutaneous calcitonin and ibandronate were added to the treatment protocol as well. Since all these medications were not effective, hemodialysis with low-calcium (1.25 mmol/L) dialysate was applied for three consecutive days, which resulted in normalization of serum calcium. Several investigations were carried out for diagnosing the underlying etiology. Positron-emission tomography (PET)/CT revealed a strong diffuse uptake of FDG in the bones and spleen. A bone marrow biopsy showed diffuse interstitial infiltration of CD20 + neoplastic B cells and, thus, post transplant lymphoproliferative disease (PTLD) was diagnosed. Tacrolimus was switched to everolimus, mycophenolate mofetil was stopped, while treatment with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) was initiated. Despite all therapeutic interventions, the patient died of septic shock in the intensive care unit on the 10th day of emergency service admission. Importance of hemodialysis as an emergent treatment modality in extreme hypercalcemia, and unfavorable course of PTLD were underlined.

Underrecognition and Underestimation of Disturbances in Calcium-Phosphate Balance in Kidney Transplant Recipients

Disturbances in mineral metabolism, namely chronic kidney disease-metabolic bone disease, became more profound with impairment of renal function. The aim of the study was to assess how often calcium, phosphate, alkaline phosphatase, and parathyroid hormone (PTH) were measured in kidney transplant recipients relative to hemodialyzed patients. In addition, prevalence of hypercalcemia defined as calcium concentration over 10.5 mg/dL was assessed.

PATIENTS AND METHODS

We studied 200 kidney allograft recipients and 100 hemodialyzed patients. Calcium, phosphate, alkaline phosphatase, 25-hydroxy vitamin D, and PTH were obtained from outpatient charts.

RESULTS

All the studied parameters were available in 100% of the hemodialyzed patients. In kidney allograft recipients, calcium and phosphate levels were available in 80%, alkaline phosphatase activity was available in 40%, PTH was available in less than 10%, and vitamin D was available in 1%. Hypercalcemia was present in 10% of hemodialyzed patients and in 5% of kidney allograft recipients. Vitamin D analogue was administered to 98% of hemodialyzed patients, whereas vitamin D was administered to 28% of kidney allograft recipients, particularly those with impaired kidney function. In conclusion, calcium and phosphate are seldom assessed on an outpatient basis in kidney allograft recipients, making the diagnosis and treatment of secondary hyperparathyroidism in this population difficult. Care of kidney transplant recipients could be substantially improved, particularly in regard to chronic kidney disease-metabolic bone disease, when regular check-ups for calcium-phosphate balance are implemented and proper treatment could be introduced to prevent further chronic kidney disease-metabolic bone disease.

Quality of Life Outcomes Associated with Variable Posttransplant Prednisone Dosing Regimens

Prednisone tapering has become more common in the management of transplant recipients. Benefits of this practice, however, must be weighed against the risks. This study identified outcomes associated with variable low dose prednisone protocols. The study sample included 98 kidney and kidney-pancreas transplant recipients 1 year after transplant. Graft function, side effects of steroid therapy, and quality of life were recorded on patients receiving 0 (n=5), 1 to 5 (n=4), 5 to 7.5 (n=5), 7.5 to 10 (n=21), and greater than 10 mg/d prednisone (n=63). Despite the fact that patients were assigned to the low dose groups because they were at risk for or already experiencing steroid induced side effects, the low dose groups presented side effect and quality of life profiles similar to or better than those of the standard dose group.

Prevalence of Hypercalcaemia in a Renal Transplant Population: A Single Centre Study

Introduction. Postrenal transplant bone disease is a significant problem. Factors influencing postrenal transplant bone status include high dose acute and low dose long-term steroid use, persistent hypercalcaemia, and graft failure. In this study, we aimed to determine the prevalence of hypercalcaemia and to evaluate the risk factors for postrenal transplant hypercalcaemia in long-term renal transplant patients at our centre. Methods. This is a biochemical audit in which we studied renal transplant recipients from the Central Northern Adelaide Renal Transplant Services, South Australia. Inclusion criteria include kidney transplant patients with functioning graft since 1971 and at least 3 months after transplantation at the time of analysis. Hypercalcaemia was defined as persistently elevated serum corrected calcium greater than or equal to 2.56 mmol/L for three consecutive months. Results. 679 renal transplant recipients with a functioning graft were studied and 101 were hypercalcaemic between March 2011 and June 2011 (15%). 60% of the hypercalcaemic patients were male and 40% were female, with chronic glomerulonephritis (39%) being the commonest cause of their end stage kidney disease (ESKD). Prevalence was similar in those that had haemodialysis and peritoneal dialysis pretransplantation. Hypercalcaemia in the renal transplant population was not secondary to suboptimal allograft function but secondary to pretransplantation hyperparathyroidism with persistent high parathyroid hormone (PTH) levels after transplantation. Conclusion. There is a high prevalence of hypercalcaemia (15%) in renal transplant recipients. The predominant cause for hypercalcaemia is pretransplantation hyperparathyroidism. The magnitude of pretransplantation hyperparathyroidism is the major determinant for long-term parathyroid function rather than graft function or pretransplantation duration on dialysis or mode of dialysis.

Comparison between paricalcitol and active non-selective vitamin D receptor activator for secondary hyperparathyroidism in chronic kidney disease: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

The goal of this systematic review is to evaluate the efficacy and safety of paricalcitol versus active non-selective vitamin D receptor activators (VDRAs) for secondary hyperparathyroidism (SHPT) management in chronic kidney disease (CKD) patients.

METHODS

PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), clinicaltrials.gov (inception to September 2015), and ASN Web site were searched for relevant studies. A meta-analysis of randomized controlled trials (RCTs) and quasi-RCTs that assessed the effects and adverse events of paricalcitol and active non-selective VDRA in adult CKD patients with SHPT was performed using Review Manager 5.2.

RESULTS

A total of 10 trials involving 734 patients were identified for this review. The quality of included trials was limited, and very few trials reported all-cause mortality or cardiovascular calcification without any differences between two groups. Compared with active non-selective VDRAs, paricalcitol showed no significant difference in both PTH reduction (MD -7.78, 95% CI -28.59-13.03, P = 0.46) and the proportion of patients who achieved the target reduction of PTH (OR 1.27, 95% CI 0.87-1.85, P = 0.22). In addition, no statistical differences were found in terms of serum calcium, episodes of hypercalcemia, serum phosphorus, calcium × phosphorus products, and bone metabolism index.

CONCLUSIONS

Current evidence is insufficient, showing paricalcitol is superior to active non-selective VDRAs in lowering PTH or reducing the burden of mineral loading. Further trials are required to prove the tissue-selective effect of paricalcitol and to overcome the limitation of current research.

Paricalcitol for secondary hyperparathyroidism in renal transplantation

Secondary hyperparathyroidism contributes to post-transplant CKD mineral and bone disorder. Paricalcitol, a selective vitamin D receptor activator, decreased serum parathyroid hormone levels and proteinuria in patients with secondary hyperparathyroidism. This single-center, prospective, randomized, crossover, open-label study compared the effect of 6-month treatment with paricalcitol (1 μg/d for 3 months and then uptitrated to 2 µg/d if tolerated) or nonparicalcitol therapy on serum parathyroid hormone levels (primary outcome), mineral metabolism, and proteinuria in 43 consenting recipients of renal transplants with secondary hyperparathyroidism. Participants were randomized 1:1 according to a computer-generated sequence. Compared with baseline, median (interquartile range) serum parathyroid hormone levels significantly declined on paricalcitol from 115.6 (94.8-152.0) to 63.3 (52.0-79.7) pg/ml (P<0.001) but not on nonparicalcitol therapy. At 6 months, levels significantly differed between treatments (P<0.001 by analysis of covariance). Serum bone-specific alkaline phosphatase and osteocalcin decreased on paricalcitol therapy only and significantly differed between treatments at 6 months (P<0.001 for all comparisons). At 6 months, urinary deoxypyridinoline-to-creatinine ratio and 24-hour proteinuria level decreased only on paricalcitol (P<0.05). L3 and L4 vertebral mineral bone density, assessed by dual-energy x-ray absorption, significantly improved with paricalcitol at 6 months (P<0.05 for both densities). Paricalcitol was well tolerated. Overall, 6-month paricalcitol supplementation reduced parathyroid hormone levels and proteinuria, attenuated bone remodeling and mineral loss, and reduced eGFR in renal transplant recipients with secondary hyperparathyroidism. Long-term studies are needed to monitor directly measured GFR, ensure that the bone remodeling and mineral effects are sustained, and determine if the reduction in proteinuria improves renal and cardiovascular outcomes.

Association of calcium, phosphate and parathyroid hormone with renal allograft function: a retrospective cohort study

BACKGROUND

Significant variations in postoperative levels of parathyroid hormone (PTH), calcium and phosphate exist after renal transplantation, but whether they affect allograft function is unknown. We investigated the association between early post-transplant levels of PTH, calcium and phosphate and graft function.

METHODS

We performed a single-centre cohort study of renal transplant recipients from Addenbrooke's Hospital, Cambridge, between April 1997 and March 2007, evaluating the association between plasma calcium, phosphate and PTH 1 month after transplantation and change in epidermal growth factor receptor (eGFR) in the first 12 months after transplantation (estimated using the Modification of Diet in Renal Disease Study equation). Differences in eGFR between 26 and 52 weeks after transplantation were computed using mixed effects linear regression models for repeated measures of eGFR, while adjusting for sociodemographic and biochemical variables.

RESULTS

Three hundred and forty-three patients were eligible for study. The mean age (standard deviation) at transplant was 43 years (13 years). Between 30 and 90 days after transplantation, the median (25th-75th percentile) eGFR was 33 (26-50) ml/min/1.73 m(2), the mean calcium level was 2.4 (0.17) mmol/l and the mean phosphate level was 0.78 (0.23) mmol/l. There was a significant interaction between calcium and phosphate levels (p = 0.006). In patients with low levels of phosphate, higher levels of calcium were associated with declining eGFR over time. However, in patients with a high phosphate level, higher calcium was associated with improved eGFR.

CONCLUSIONS

Higher serum calcium in patients with low serum phosphate after transplantation is associated with a decline in graft function during the first year after transplantation. Disorders of mineral metabolism after transplant may represent an important therapeutic target to preserve allograft function.

Successful salvage therapy with Daptomycin for osteomyelitis caused by methicillin-resistant Staphylococcus aureus in a renal transplant recipient with Fabry-Anderson disease

Daptomycin is licensed in adults for the management of Staphylococcus aureus methicillin-resistant infections, including bone and skin complicated infections. We describe for the first time its use in a renal transplant recipient for Fabry-Anderson Disease with right heel osteomyelitis. The patient was unresponsive to first-line Teicoplanin and second-line Tigecycline, whereas he was successfully treated with third-line Daptomycin monotherapy at 4 mg/Kg/qd for 4 weeks. Local debridement was performed in advance of each line of treatment.

Bone mineral density in patients with end-stage renal disease and its evolution after kidney transplantation

Renal transplantation is associated with abnormalities of the structure and function of the musculoskeletal system. No data are available on bone health in Indian patients with end-stage renal disease (ESRD) and its evolution after transplantation. Consecutive ESRD patients who underwent living donor renal transplantation were studied prospectively. Bone mineral density (BMD) was measured at lumbar vertebrae using quantitative computed tomography (CT) scan before transplantation and after 3 and 6 months. T and Z scores were calculated by comparing with normal control data, and values were correlated with various clinical and biochemical parameters. Of the 56 patients enrolled (mean age, 33.7 years; 47 males), 40 completed the 6-month follow-up. The vertebral trabecular bone density at the time of transplantation was 172±53 mg/cc and the average Z score was 0.26±1.7. There was a significant decline in BMD at 3 months (11.8%; P<0.0001) and 6 months (16%; P<0.0001) after transplantation. Both T and Z scores showed a significant decline at 3 and 6 months. There was a significant decline in intact parathormone (iPTH) levels after transplantation, but 15 (37.5%) patients continued to have raised iPTH 6 months after transplantation. The iPTH levels at 6 months had significant correlation with BMD decline (r=0.43, P=0.006). We conclude that Indian ESRD patients have relatively well-preserved BMD, but the density declines rapidly after transplantation. A significant proportion of patients exhibit persistent hyperparathyroidism 6 months after transplantation, which correlates with bone loss.

Impaired regulation of calcium excretion in kidney transplant recipients

Disorders of mineral metabolism and hypercalcemia are frequent in kidney transplant recipients. Calcium to creatinine (Ca/Cr) clearance ratio was used as a criterion to distinguish between different calcium metabolism disorders. The study comprised 91 (53 men, 38 women) kidney recipients aged 23-70 years, with creatinine clearance (CrCl) >60 ml/min. The following parameters related to mineral metabolism were measured in serum: iPTH, total alkaline phosphatase (tALP), telopeptide (bone degradation marker, CTX), 25(OH)D(3), total and ionized calcium, Ca(++), Pi, creatinine (Cr). Creatinine and Ca were also determined in urine, as well as Ca/Cr clearance ratio. According to the Ca/Cr clearance ratio, patients were divided into three groups as follows: <0.01 (found in disorders caused by reduced calcium-sensing receptor sensitivity, N = 30), 0.01-0.02 (normal value, N = 45), and >0.02 (found in hyperparathyroidism, N = 16). In the group of patients with Ca/Cr clearance ratio <0.01, seven patients had hypercalcemia, and four patients had hypercalcemia and elevated iPTH. It seems that impairment of renal calcium excretion may occur in kidney transplant recipients with good kidney function. Inappropriately low calciuria and impaired sensitivity of calcium-sensing receptor may be pathogenetic factors causing hypercalcemia in kidney transplant recipients.

Tertiary excess of fibroblast growth factor 23 and hypophosphatemia following kidney transplantation

Hypophosphatemia caused by inappropriate urinary phosphate wasting is a frequent metabolic complication of the early period following kidney transplantation. Although previously considered to be caused by tertiary hyperparathyroidism, recent evidence suggests a primary role for persistently elevated circulating levels of the phosphorus-regulating hormone, FGF23. In the setting of a healthy renal allograft, markedly increased FGF23 levels from the dialysis period induce renal phosphate wasting and inhibition of calcitriol production, which contribute to hypophosphatemia. While such tertiary FGF23 excess and resultant hypophosphatemia typically abates within the first few weeks to months post-transplant, some recipients manifest persistent renal phosphate wasting. Furthermore, increased FGF23 levels have been associated with increased risk of kidney disease progression, cardiovascular disease, and death outside of the transplant setting. Whether tertiary FGF23 excess is associated with adverse transplant outcomes is unknown. In this article, we review the physiology of FGF23, summarize its relationship with hypophosphatemia after kidney transplantation, and speculate on its potential impact on long-term outcomes of renal allograft recipients.

Immunosuppressive agents and bone disease in renal transplant patients with hypercalcemia

Renal transplantation is the definitive treatment for many metabolic abnormalities of uremic patients, although it is only partially effective for renal osteodystrophy, which may interact with posttransplant renal osteopathy. Osteopenic-osteoporotic syndrome represents, together with fractures secondary to osteoporosis and osteonecrosis, the bone complication most related to renal transplantation. Several factors contribute to the pathogenesis of posttransplantation osteoporosis, particularly immunosuppressive treatment. In this study, we evaluated the prevalence of factors related to posttransplant renal osteopathy and the clinical impact of immunosuppressive protocols. We studied 24 renal transplant recipients with hypercalcemia. Glomerular filtration rate was >50 mL/min. Mean age, time on dialysis, and time from transplantation were 49.6, 5.4, and 6.9 years, respectively. We evaluated serum and urine calcium and phosphorus, calcitonin, parathormone, bone-specific alkaline phosphatase, osteocalcin, urine deoxypyridinoline, telopeptide of type 1 procollagen, 1,25-(OH)(2) and 25-OH vitamin D, parathyroid ultrasound, and computerized bone mineralometry. The combination of sirolimus and steroids resulted in the most disadvantageous outcomes regarding alkaline phosphatase and mineralometry. Calcineurin inhibitors did not significantly influence bone metabolism markers; mycophenolate mofetil evidenced no effect on bone. According to the literature, steroids account for the abnormalities found in our patients and in severe osteopenia. Several factors may contribute to the development of osteoporosis and fractures in transplantation patients, although they are overcome by the prominent effect of steroids. In patients at high risk of osteoporosis, steroid-free therapy should be considered. Everolimus is indicated for diseases with bone loss. Combined therapy with everolimus and mycophenolic acid without cyclosporine and steroids, seemed to be particularly indicated. Prophylactic treatments should be commenced early. No single marker was useful to diagnose posttransplant renal osteopathy. The definitive diagnosis should be made by bone biopsy during transplantation, and noninvasive procedures, such as densitometry and evaluation of biologic markers, may be useful during follow-up.

Does statin usage reduce the risk of corticosteroid-related osteonecrosis in renal transplant population?

The relationship between corticosteroids and osteonecrosis is well known. Limited data suggest that statins modulate cholesterol metabolism and may protect against osteonecrosis. The authors analyzed their prospective renal transplant database to determine if statin usage reduces the incidence of corticosteroid-related osteonecrosis and identified 2,881 renal transplantation patients who met the entry criteria. Among 338 patients on statins, 15 (4.4%) developed osteonecrosis, versus 180 of 2,543 (7%) patients who were not on statins. Osteonecrosis-free survival was similar in patients with and without statin exposure.

Degree of corticosteroid treatment within the first 2 months of renal transplantation has a strong influence on the incidence of osteonecrosis of the femoral head

BACKGROUND AND PURPOSE

It has been suggested that avascular osteonecrosis (AVN) of the femoral head develops early after renal transplantation. We evaluated the relationship between risk of AVN and dose of steroids administered in different time periods.

METHODS

Development of AVN was determined using MRI at 3-6 weeks, 9-12 weeks, 24 weeks, and 12 months after transplantation in 150 patients (96 males). We investigated possible associations between acute rejection reactions, the dose of cyclosporine, tacrolimus use, total steroid dose by the second, fourth, sixth, or eighth weeks after transplantation, and incidence of AVN.

RESULTS

There was no statistically significant difference between incidence of AVN and presence or absence of an acute rejection reaction. We found a statistically significant association between AVN incidence and the total dose of steroids administered during the first 2 months after transplantation, and there was a doseresponse relationship. No other statistically significant associations were found.

INTERPRETATION

Our findings confirm that the total dose of steroids given within the first 2 months after renal transplantation has a great influence on the incidence of AVN.

Pharmacokinetics and pharmacodynamics of cinacalcet in patients with hyperparathyroidism after renal transplantation

Cinacalcet is a calcimimetic drug for the treatment of secondary hyperparathyroidism (HPT). In a sequential open-label study, ten patients with persistent HPT after renal transplantation received first 30 and then 60 mg oral cinacalcet once daily over 2 weeks each. Cinacalcet steady state oral clearance was 131.1 +/- 20.9 l/h and 92.8 +/- 9.5 l/h (mean +/- SE) after 30 and 60 mg, respectively. Cinacalcet and parathyroid hormone (PTH) concentrations showed an inverse correlation and were fitted to a simple E(max) model (E(max) = 80% reduction vs. baseline, EC(50) = 13 ng/mL). A once daily administration of cinacalcet lowered serum calcium over 24 h without fluctuations. The 8-h fractional urinary excretion of calcium was increased after 60 mg cinacalcet (baseline 0.85 +/- 0.17%, 30 mg 1.53 +/- 0.35%, 60 mg 1.92 +/- 0.37%). Renal function remained stable. Cinacalcet pharmacokinetics and pharmacodynamics showed a pronounced interindividual variability. We conclude that the once daily administration of cinacalcet in patients with secondary HPT after renal transplantation effectively reduced iPTH and serum calcium. The transient calciuria could potentially favor nephrocalcinosis and reduce bone mineral density, suggesting that higher doses of cinacalcet need to be used with caution in renal transplant recipients with severe persistent hyperparathyroidism.

Medical comorbidities after renal transplantation

BACKGROUND

Despite the amount of evidence regarding the negative impact of medical comorbidities after transplantation, little attention has been directly paid to the pattern of somatic comorbidities in renal transplant recipients. The aim of this study was to assess the prevalence of medical comorbidities after kidney transplantation.

METHODS

In a cross-sectional study during 2006, we evaluated 119 kidney transplant recipients for somatic comorbidities by using the Ifudu comorbidity index, which evaluated the presence of 14 chronic illnesses among patients undergoing maintenance hemodialysis. Correlations of the Ifudu score with demographic and clinical data were also studied.

RESULTS

Eighty-three (90.4%) subjects had at least one medical comorbidity. The mean comorbidity score was 5.17 +/- 4.50. The most frequent comorbidities were nonischemic heart diseases including hypertension (n=75; 63%), visual disturbances (n=42; 35.2%), low back pain and spine and joint disorders (n=30; 25.21%), and musculoskeletal disorders (n=28; 23.5%). A higher comorbidity score was significantly correlated with lower economic status (P<.05), but not with age, gender, marital status, educational level, cause, or duration of end-stage renal disease.

CONCLUSION

The prevalence of medical comorbidities among kidney transplant recipients seems to be high, with the highest prevalence due to nonischemic heart diseases, visual disturbances, and musculoskeletal disorders. This highlighted the necessity of providing posttransplant care by a multidisciplinary team of specialists.

Prognostic associations of serum calcium, phosphate and calcium phosphate concentration product with outcomes in kidney transplant recipients

Disturbances in calcium and phosphate metabolism have been linked to increased mortality in hemodialysis patients, but not in kidney transplant recipients (KTR). We enrolled 733 KTR from the Vienna General Hospital into this study. Detailed demographic, clinical, laboratory, and transplant-related information was collected at baseline. We used the Austrian Dialysis and Transplantation Registry for follow-up. Using multivariate proportional hazard regression, we examined the independent associations between serum calcium, serum phosphate, and calcium phosphate (CaPO(4)) product with the outcomes of death from any cause and kidney allograft loss. Over a median follow-up of >6 years, 154 patients died and 259 kidney allografts were lost. Associations with serum calcium, phosphate concentrations, and CaPO(4) product concentrations were found for allograft loss, but not for patient mortality. Patients in the highest quintile of phosphate concentration and CaPO(4) product had an increased risk for allograft loss compared with patients in the lowest quintile of these parameters (hazards ratio, HR = 2.15; 95% confidence interval, CI: 1.36-3.40 and HR = 1.72; 95% CI: 1.10-2.71, respectively). High calcium levels were associated with a reduced risk for allograft loss. Results were even more pronounced for death-censored allograft loss. High concentrations of serum phosphate and CaPO(4) product were associated with an increased risk for allograft loss in these KTR, whereas high serum calcium concentrations seemed to lower the risk.

Persistent hypercalcemia is a significant risk factor for graft dysfunction in renal transplantation recipients

Hypercalcemia is a common problem in renal transplant recipients, although in most cases, spontaneous resolution occurs within 1 year after renal transplantation. This condition may persist in some patients producing effects on renal function which are not well understood. In this study, we sought to analyze the effect of persistent hypercalcemia in the posttransplantation period on the function of renal transplants. A total of 121 recipients (31 women, 90 men; mean age, 34.1 +/- 9.9 years) underwent renal transplantation between 1999 and 2002. All patients underwent prospective evaluation of their serum calcium levels at 6-month intervals. A sustained corrected mean serum calcium level higher than 10.2 mg/dL was defined as "persistent hypercalcemia." Patients who had a gradual increase in their serum creatinine levels to >2 mg/dL or a 50% rise above the baseline were considered to display chronic allograft dysfunction (CAD). Among 121 recipients, 52 patients (43%) developed CAD and 37 patients (30.6%) had persistent hypercalcemia. Among the CAD patients, 22 suffered persistent hypercalcemia, while the other 15 patients were without CAD, a difference that was statistically significant (42.3% vs 21.7%, P = .01). The mean calcium levels were lower among patients without than with CAD, a difference that did not reach statistical significance (9.9 +/- 0.4 mg/dL vs 10.1 +/- 0.6 mg/dL, P = .1). In conclusion, persistent hypercalcemia in the posttransplantation period may significantly contribute to the development of chronic allograft nephropathy.

Evaluation of cortical bone by peripheral quantitative computed tomography in renal transplant recipients

BACKGROUND

The absolute risk of fractures in renal transplant patients is 3 times that of matched controls. Most of the symptomatic fractures are peripheral, suggesting a greater compromise of cortical bone. Peripheral quantitative computed tomography (pQCT) is a new imaging technique that allows separate noninvasive evaluations of cortical and trabecular bones. We investigated cortical bone by pQCT in 12 renal transplant patients (seven men and five women) for comparison with 27 normal controls.

METHODS

pQCT (XCT 960, Stratec, Pforheim, Germany) was performed upon the distal radius of the nondominant forearm (15% the length of the ulna, proximal from the radius end plate). We evaluated total and cortical bone mineral density (TBMD, cBMD), total (cross-sectional) and cortical area (TA, cA), cortical thickness (cThk), endosteal and periosteal circumferences, and the buckling ratio (r/cThK).

RESULTS

Compared with normal controls transplant patients as a whole showed a significant increase in TA, in endosteal circumference (P < .001), and in the buckling ratio (P < .001) with a significant reduction in cThK (P < .001). Female patients had a marked decrease in cA (51.4 vs 69.3 [pixel n]; P < .0001) and cThK (2.08 vs 2.78 mm; P < .0001). Male patients also had a decrease in cThK (2.54 vs 3.30 mm; P = .0001) and an increase in endosteal perimeter (31.2 vs 26.4 mm; P < .0001). Total time on dialysis prior to renal graft correlated negatively with cortical thickness (r = .62; P < .01).

CONCLUSIONS

Our results suggest that a marked thinning of cortical bone may explain the increased incidence of peripheral fractures among renal transplant patients.

Secondary hyperparathyroidism is associated with vitamin D receptor polymorphism and bone density after renal transplantation

Immunosuppresive treatment and secondary hyperparathyroidism (SHPT) are considered among the most important pathogenetic factors for post-renal transplant bone disease. The aim of this study was to investigate the relationships among vitamin D receptor (VDR) gene polymorphism, parathyroid hormone (PTH) levels and bone density in renal transplant recipients. We enrolled 75 patients (50 male and 25 female, mean age 47+/-11 years) who had undergone kidney transplantation 53+/-4 months before. All patients underwent an evaluation of the main biochemical parameters of bone metabolism as well bone densitometry. VDR alleles were typed by a PCR assay based on a polymorphic BsmI restriction site. When patients were categorized according to the VDR genotype (BB, Bb, bb), serum creatinine and the cumulative doses of immunosuppressive drugs were similar across the groups. PTH levels higher than 80 pg/ml were found in 53.6% of the patients, with the highest values being detected in the bb VDR genotype (P<0.05). PTH was significantly correlated to urinary NTx values. Bone density was low in the whole population; however, spinal bone density was lower in the bb subgroup (P<0.02). In the whole population, only PTH (P<0.05) and body mass index (P<0.01) were independent predictors of spinal bone density. Grouping patients by the VDR gene polymorphism, only PTH continued to be an independent predictor of spinal bone density in the bb allele subgroup (R(2) Adj.=0.17). We can conclude that the VDR genotype polymorphism affects bone density of renal transplant recipients via its effects on the severity of SHPT.

Treatment with intermittent calcitriol and calcium reduces bone loss after renal transplantation

BACKGROUND

Bone loss occurs during the first 6 months after renal transplantation (RT), and corticosteroid therapy plays an important role. Although calcium plus vitamin D administration prevents corticosteroid-induced osteoporosis, its use in RT recipients is limited by the risk of hypercalcemia.

METHODS

This double-blind, randomized, and controlled prospective intervention trial examined the effect of intermittent calcitriol (0.5 microg/48 h) during the first 3 months after RT, plus oral calcium supplementation (0.5 g/day) during 1 year with calcium supplementation alone. The primary outcome measure was the change in bone mineral density (BMD) at 3 and 12 months after RT; we also explored whether the effect of calcitriol on BMD was different among vitamin D receptor (VDR) genotypes (BsmI). Forty-five recipients were randomized to calcitriol therapy (CT) and 41 were randomized to placebo (PL).

RESULTS

Both groups had a similar degree of pre-existing hyperparathyroidism (197 +/- 229 vs. 191 +/- 183 pg/mL), but a more pronounced decrease of parathyroid hormone (PTH) levels after RT was observed in CT patients (at 3 months: 61.4 +/- 42.2 vs. 85.7 +/- 53.1 pg/mL, P= 0.02; at 12 months: 67.3 +/- 33.7 vs. 82.6 +/- 37 pg/mL; P= 0.08). CT patients preserved their BMD at the total hip significantly better than those on PL (3 months: 0.04 +/- 3.3 vs. -1.93 +/- 3.2%, P= 0.01; 12 months: 0.32 +/- 4.8 vs. -2.17 +/- 4.4%, P= 0.03); significant differences were noted at the intertrochanter, trochanter, and Ward's triangle. Differences did not reach significance at the femoral neck. Two CT patients (4.4%) and 4 PL patients (9.8%) developed a hypercalcemic episode during the first 3 months after RT. The effect of CT on BMD at 3 months was more prominent in recipients with the at-risk allele of the VDR gene (P= 0.03).

CONCLUSION

Therapy with low-dose calcium supplements during 1 year, plus intermittent calcitriol for 3 months after RT, is safe, decreases PTH levels more rapidly, and prevents bone loss at the proximal femur; a more pronounced effect is seen in recipients with at least one at-risk allele of the VDR genotype.

Early rapid loss followed by long-term consolidation characterizes the development of lumbar bone mineral density after kidney transplantation

BACKGROUND

Bone mineral density (BMD) decreases significantly early after renal transplantation. This prospective study was designed to evaluate the long-term lumbar BMD development.

METHODS

Sixty-three renal-transplant recipients (mean age 44 +/- 12 years, 37 [59%] male) underwent serial yearly posttransplant laboratory parameter and BMD measurements of the lumbar spine (dual energy x-ray absorptiometry). Combined maintenance immunosuppression included prednisolone in 95% of patients. The minimum number of consecutive scans was three; the maximum number seven (n = 15). Examinations were performed between 3 +/- 2 and 68 +/- 4 months posttransplant.

RESULTS

BMD was significantly lower compared with healthy controls at all times after transplantation. t scores were below -1. BMD development revealed a biphasic pattern: between 3 +/- 2 and 10 +/- 2 months, a significant BMD decrease of -0.016 +/- 0.055 g/cm2 (-1.6%, P = 0.024) occurred. Later, a moderate increase resulting in BMD stability until the sixth year posttransplant was detected. Within the first year, posttransplant osteocalcin (from 19 +/- 15 to 32 +/- 23 microg/L) and calcitriol (from 24 +/- 15 to 43 +/- 24 ng/L) displayed a significant increase. Compared with patients with a pronounced decrease, patients with a substantial increase in early posttransplant BMD had a lower baseline BMD (0.989 +/- 0.131 vs. 1.149 +/- 0.202 g/cm2 [P = 0.0122]) and lower creatinine levels (105 +/- 23 vs. 141 +/- 53 mmol/L [P = 0.0227]).

CONCLUSION

Our study confirms a significant decrease of lumbar BMD early after renal transplantation. Bone loss was less pronounced than previously described. The longitudinal follow-up verifies a previously assumed biphasic lumbar BMD development: after the first year, no further significant bone loss occurred, and bone density remained relatively stable at significantly lower levels compared with healthy controls.

Risk factors for nontraumatic osteonecrosis of the femoral head after renal transplantation

We investigated risk factors for osteonecrosis of the femoral head (ONF) in renal transplant recipients, who are susceptible to the disease. Among 287 renal transplant recipients, 18 ONF patients with enough data were included, and 18 age- and sex-matched recipients without ONF were nominated as reference cases. Risk factors were analyzed using a conditional logistic regression method. There were no differences between the ONF patients and the reference cases regarding the types of immunosuppressant or the donor (living or cadaveric, father or mother, matching blood type and human leukocyte antigens). The daily oral steroid dosage (prednisolone 25.0 mg/day or more) and blood urea nitrogen level 2 months after transplantation were the only factors with relevance to the occurrence of ONF. We propose that oral steroid dosages should be low or reduced after renal transplantation, and acute rejection should be controlled with pulsed therapy.

Long-term fracture risk following renal transplantation: a population-based study

Abnormal bone metabolism is a recognized complication of end-stage renal disease, but fracture risk following renal transplantation has not been well quantified. We followed the 86 Olmsted County, Minnesota, residents who underwent initial renal transplantation in 1965-1995 for 911 person-years (median, 10.6 years per subject) in a retrospective cohort study. Fractures, and possible risk factors, were assessed through review of each subject's complete community medical records. Altogether, 117 fractures were observed during follow-up extending to 33 years. The cumulative incidence of any fracture at 15 years was 60% versus 20% expected ( P<0.001). There was a significantly increased risk of fractures generally [standardized incidence ratio (SIR), 4.8; 95% CI, 3.6-6.4] and vertebral (SIR, 23.1; 95% CI, 12.3-39.6) and foot fractures (SIR, 8.4; 95% CI, 5.1-12.9) especially. Age at first transplantation, renal failure due to diabetes, pancreas transplantation, peripheral neuropathy, peripheral vascular disease and blindness were all associated with overall fracture risk. In a multivariate analysis, however, only age and diabetic nephropathy were independent predictors of fracture risk generally, while higher activity status was protective. Diabetes was the only independent predictor of lower limb fractures, whereas age and osteoporosis history predicted vertebral fractures. Cumulative corticosteroid dosage was not associated with increased fracture risk in this analysis. Despite the fact that our patients had few risk factors for preexisting bone disease attendant to postmenopausal osteoporosis, prior corticosteroid use or renal osteodystrophy, these data indicate that renal transplantation is associated with a significant increase in fracture risk among unselected patients in the community. Diabetic patients, particularly, experience excess lower limb fractures. Patients and their care providers should be aware of this elevated fracture risk, which continues long-term.

Lovastatin inhibits adipogenic and stimulates osteogenic differentiation by suppressing PPARgamma2 and increasing Cbfa1/Runx2 expression in bone marrow mesenchymal cell cultures

The mechanism whereby lovastatin can counteract steroid-induced osteonecrosis and osteoporosis is poorly understood. We assessed the effect of lovastatin on a multipotential cell line, D1, which is capable of differentiating into either the osteoblast or the adipocyte lineage. The expression of bone cell and fat cell transcription factors Cbfa1/Runx2 and PPARgamma2, respectively, were determined. 422aP2 gene expression was analyzed. Osteocalcin promoter activity was measured by cotransfecting the cells with the phOC-luc and pSV beta-Gal plasmids. Lovastatin enhanced osteoblast differentiation as assessed by a 1.8x increase in expression of Cbfa1/Runx2 and by a 5x increase in osteocalcin promoter activity. Expression of PPARgamma2 was decreased by 60%. By enhancing osteoblast gene expression and by inhibiting adipogenesis, lovastatin may shunt uncommitted osteoprogenitor cells in marrow from the adipocytic to the osteoblastic differentiation pathway. Future evaluation of lovastatin and other lipid-lowering drugs will help determine their potential as therapeutic agents for osteonecrosis and osteoporosis.

Hyperphosphaturia after kidney transplantation in syngeneic rats: effects on nephrocalcinosis and bone metabolism?

BACKGROUND

Studies on kidney transplantation have thus far mainly dealt with surgical techniques, immunology, and transplant tolerance. Disturbed mineral metabolism after renal denervation has not received much attention. Basic physiological research in short-term experiments has shown that experimental renal denervation in rats leads to parathormone (PTH)-independent hyperphosphaturia (HPU). HPU and other metabolic complications also have been described after clinical kidney transplantation. Furthermore, there is an unexpected increase in the risk of bone fracture. However, these studies have examined an organism pre-damaged with regard to the parathyroid and immunosuppression. Experimental investigations in syngeneic rats were performed to see whether HPU also occurs after transplantation and thus after denervation and which target organs are involved.

METHODS

Thirty-six male Lewis rats subjected to laparotomy (n = 12), unilateral nephrectomy (n = 12), or unilateral transplantation and bilateral nephrectomy (n = 12) were observed for 18 weeks.

RESULTS

Animals that underwent transplantation had a significant loss of phosphate in the urine not associated with decreased calcium, phosphate, or magnesium in bone. Stability test showed no deterioration, despite a slight increase in the bone parameters of alkaline phosphatase, cyclic AMP, and hydroxyproline with unchanged calciotropic hormones. Nephrocalcinosis was not observed. Parallel to HPU, there was a compensatory reduction in fecal phosphate excretion.

CONCLUSIONS

The loss of phosphate after clinical kidney transplantation in the predamaged parathyroid hormone control system as well as immunosuppression and a surprising increase in the incidence of bone fractures may be explained by the denervation-related loss of phosphate. The lack of intestinal counter-regulation could be an important pathomechanism.

Development of lumbar bone mineral density in the late course after kidney transplantation

BACKGROUND

Rapid bone loss is a frequent finding early after kidney transplantation. Only limited data are available on the bone mineral density (BMD) in long-term kidney transplant recipients.

METHODS

In 26 kidney transplant recipients (13 men and 13 women, age 45.3 +/- 12.3 years), serum biochemical markers of bone metabolism and BMD at the lumbar vertebrae L2-4 were evaluated prospectively in three serial examinations (E1, E2, E3; method: dual-energy X-ray absorptiometry). Examinations were performed at 47 +/- 2 months, 59 +/- 2 months, and 71 +/- 2 months after transplantation. All patients received standard dual or triple immunosuppression including prednisolone.

RESULTS

The mean BMD was significantly lower (P < 0.001) than in sex-matched young controls: T-score was -1.43 +/- 1.49 (E1), -1.39 +/- 1.40 (E2), and -1.44 +/- 1.30 (E3). The BMD did not change significantly (Delta BMD, -0.5 +/- 5.9%) from E1 to E3. Regression analysis did not show significant associations between Delta BMD and biochemical parameters or prednisolone dosage. No clinically apparent new lumbar vertebral fracture occurred. The mean intact parathyroid hormone was 110.1 +/- 97.5 pg/mL (E1), 121 +/- 102.7 pg/mL (E2), and 134.5 +/- 128.6 pg/mL (E3). Serum creatinine was 1.44 +/- 0.45 (128 +/- 40) mg/dL (micromol/L) (E1), 1.44 +/- 0.47 (127 +/- 42) mg/dL (micromol/L) (E2), and 1.45 +/- 0.70 (128 +/- 62) mg/dL (micromol/L) (E3). Ten patients (38.5%) showed an increase of BMD (+5.7 +/- 3.2%) and 15 patients (57.7%) showed a decrease of -4.7 +/- 3.2% (P < 0.0001). Both groups were different in T-scores at E1 (-2.29 +/- 1 versus -0.88 +/- 1.5); intact parathyroid hormone, creatinine, vitamin D levels, and prednisolone dosage were not significantly different.

CONCLUSION

This study shows that lumbar BMD is reduced in long-term kidney transplant recipients. During our 24-month observation period, overall lumbar BMD remained stable.

The effects of vitamin D receptor polymorphism on secondary hyperparathyroidism and bone density after renal transplantation

Immunosuppresive treatment and secondary hyperparathyroidism (SHPT) are considered among the most important pathogenetic factors for postrenal transplant bone disease. The aim of this study was to investigate the relationships among vitamin D receptor (VDR) gene polymorphism, parathyroid hormone (PTH) levels, and bone density in renal transplant recipients. We enrolled 69 patients (47 men and 22 women; mean age, 47 +/- 11 years) who had undergone kidney transplantation 51 +/- 5 months before. All patients underwent an evaluation of the main biochemical parameters of bone metabolism as well as bone densitometry. VDR alleles were typed by a polymerase chain reaction (PCR) assay based on a polymorphic BsmI restriction site. When the patients were categorized according to the VDR genotype (BB, Bb, and bb), serum creatinine, and the cumulative doses of immunosuppressive drugs were similar across the groups. PTH levels higher than 80 pg/ml were found in 53.6% of the patients, with the highest values being detected in the bb VDR genotype (p < 0.05). PTH was significantly correlated to urinary type I collagen cross-linked N-telopeptide (NTx) values. Bone density was low in the whole population; however, spinal bone density was lower in the bb subgroup (p < 0.02). In the whole population, only PTH (p < 0.05) and body mass index (BMI; p < 0.01) were independent predictors of spinal bone density. When grouping the patients by the VDR gene polymorphism, only PTH continued to be an independent predictor of spinal bone density in the bb allele subgroup (R2 adj. = 0.17). We can conclude that the VDR genotype polymorphism affects bone density of renal transplant recipients via its effects on the severity of SHPT.

The effect of fluvastatin of hyperlipidemia in renal transplant recipients: a prospective, placebo-controlled study

Posttransplant hyperlipidemia is a common complication which may affect long term cardiovascular mortality. In this prospective, placebo-controlled study, 19 renal transplant recipients (11 male 8 female, mean age 31.2 +/- 8.4 years) with good allograft function (serum creatinine <2 mg/dl) more than 6 months after transplantation were included. All the patients had hyperlipidemia (serum cholesterol >230 mg/dl and/or LDL-cholesterol >130 mg/dl) despite dietary interventions. The patients were treated with a triple immunosuppressive regimen. After a 8-week period of placebo plus diet regimen, the patients were put on fluvastatin plus diet for another 8 weeks. The patients were followed for its effect on lipid parameters and side effects. After convertion to fluvastatin, serum cholesterol (263.0 +/- 31.6 vs 223.2 +/- 31.6 mg/dl, p = 0.001), LDL-cholesterol (174.4 +/- 28.3 vs 136.4 +/- 28.5 mg/dl, p = 0.002), Apolipoprotein (Apo) A1 (131.1 +/- 16.9 vs 114.7 +/- 18.4 mg/dl, p = 0.001) and Apo B (109.0 +/- 29.8 vs 97.3 +/- 31.5 mg/dl, p = 0.02) levels decreased significantly. Serum levels of triglycerides, VLDL-cholesterol and HDL-cholesterol levels did not vary under fluvastatin. Serum lipoprotein (a) levels were also unchanged during the whole study period (24.9 +/- 19.4 vs 23.1 +/- 19.8 mg/dl, p > 0.05). We concluded that fluvastatin effectively decreased atherogenic lipoproteins such as serum cholesterol, LDL-cholesterol, Apo B in posttransplant hyperlipidemia, however fluvastatin had no effect on another independent risk factor of atherogenesis, serum lipoprotein (a) levels.

Treatment with vitamin D and calcium reduces bone loss after renal transplantation: a randomized study

A decrease in bone mineral density (BMD) is a major complication of renal transplantation (RTx), predominantly occurring within the first 6 mo after RTx. The most important causative factor is the use of corticosteroids, but persisting hyperparathyroidism and abnormalities in vitamin D metabolism play a role too. This study examines the effect of treatment with calcium and active vitamin D on the loss of BMD in the first 6 mo after RTx. A total of 111 renal transplant recipients (65 men, 46 women; age, 47 +/- 13 yr) were randomized to either treatment with active vitamin D (0.25 microg/d) plus calcium (1000 mg/d) (CaD group), or to no treatment (NoT group). Immunosuppressive therapy consisted of cyclosporine, prednisone, and mycophenolate mofetil. Laboratory parameters and BMD (lumbar spine and hip) were measured at 0, 1 (laboratory only), 3, and 6 mo after RTx. Lumbar BMD was nearly normal at the time of RTx. In both groups, a significant decrease in lumbar BMD was observed during the first 3 mo (CaD, -3.3 +/- 4.3%; P < 0.0001; NoT, -4.1 +/- 4.8%; P < 0.0001). Between the third day and sixth month, lumbar BMD slightly recovered in the CaD group, but it decreased further in the NoT group (total loss 0 to 6 mo: CaD, -2.6 +/- 5.0% [P < 0.001]; NoT, -5.0 +/- 4.7% [P < 0.0001]). As a result, the amount of bone loss at 6 mo was significantly lower in the CaD group (P = 0.02). Loss of BMD at the different femoral sites was also significantly reduced in the CaD group. Apart from a trend toward more frequent hypercalcemia in the CaD group, no clinical or biochemical differences existed between the groups. Treatment with a low dose of active vitamin D and calcium partially prevents bone loss at the lumbar spine and proximal femur during the first 6 mo after RTx.