| 2007 JASN IMPACT FACTOR 7.111 | HOME AUTHOR INFO EDITORIAL BOARD SUBSCRIBE FEEDBACK ALERTS HELP | |||
| CURRENT ISSUE | ARCHIVES | JASN Express | ONLINE SUBMISSION | |
CLINICAL SCIENCE |



*Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York; and
University of Kentucky, Lexington, Kentucky
Correspondence to Dr. Maria Coco, Montefiore Medical Center, 111 East 210th Street, Bronx, New York 10467. Phone: 718-920-4136; Fax: 718-652-8384;
| Abstract |
|---|
|
|
|---|
| Introduction |
|---|
|
|
|---|
Corticosteroids induce bone loss through depressive effects on osteoblastic activity and enhancing effects on osteoclastic activity (5,6), lowering of gastrointestinal calcium absorption, increased renal calcium excretion, and increased parathyroid hormone (PTH) secretion, all resulting in decreased bone mass (5). Cyclosporine and tacrolimus can affect bone remodeling which can result in increased bone loss (7,8). As a result, 6.8 and 8.8% of bone mineral density (BMD) can be lost by 6 and 18 mo, respectively, after successful renal transplantation (9). Consequently, there is an increased risk for fractures in this population (10).
Bone loss in patients with osteoporosis or those who receive corticosteroid therapy has been treated effectively with bisphosphonates (3,11,12). Bisphosphonates decrease bone turnover mainly by inhibiting osteoclast activity. They have been used with varying success in treatment of bone loss associated with cardiac (13,14) and liver transplantation (1517). Recent studies have shown favorable effects on BMD in renal transplant recipients (18,19).
It has been shown that renal transplant recipients develop low bone turnover with time (20). A cross-sectional study in renal transplant patients demonstrated a high prevalence of low-turnover or adynamic bone disease with and without mineralization defect (4). Thus, there is concern that bisphosphonates, in depressing bone turnover, may exacerbate adynamic bone disease in renal transplant recipients (21).
The purpose of this study was to determine whether pamidronate, a bisphosphonate, when given prophylactically, is useful in preserving BMD after renal transplantation and whether it is associated with oversuppression of bone turnover and thus a higher risk of adynamic bone disease.
| Materials and Methods |
|---|
|
|
|---|
Subjects
Inclusion criteria encompassed all adult transplant recipients who were hemodynamically stable perioperatively. The recipients were approached either before the renal transplant or within 36 h postoperatively if their BP and electrolytes were stable. A negative serum pregnancy test was required before the surgery. Exclusion criteria included inability to return for regular follow-up or participation in another clinical trial.
Protocol
Subjects were randomized via a computer-generated number system to one of two groups. The treatment group (PAM) received intravenous pamidronate plus oral calcitriol and calcium carbonate. The control group (CON) received oral calcitriol and calcium carbonate alone. PAM patients received 60 mg of pamidronate within 48 h after transplantation followed by 30 mg at months 1, 2, 3, and 6. Subjects in both groups received oral calcitriol and calcium carbonate from months 1 to 12 to maintain serum calcium between 8.5 and 10.5 mg/dl. Pamidronate was chosen because it is the only bisphosphonate whose use is not explicitly contraindicated in renal failure, it has a good safety profile in renal failure, and it can be given intravenously.
A subgroup of subjects who were undergoing scheduled living donor renal transplantation underwent anterior iliac crest biopsies immediately before transplantation and 6 mo thereafter. When possible, the subjects received tetracycline for labeling of bone before the baseline bone biopsy (we were unable to complete tetracycline labeling in some cases because of the inability to predict the exact timing of the transplantations); all subjects who underwent follow-up bone biopsy received tetracycline labeling. The labeling schedule consisted of 2-d oral administration of tetracycline hydrochloride (500 mg twice daily), followed by a free interval of 12 d and subsequent administration of 4 d of demeclocycline (300 mg twice daily). Bone biopsies were performed 4 d thereafter. Bone biopsies (0.5 cm diameter x 2 to 4 cm length) were taken from the anterior iliac crest using the one-step electric drill technique (Straumann Medical, Waldenburg, Switzerland; MD Tech) as described previously (22).
Subjects received standard immunosuppression with glucocorticoids and cyclosporine or tacrolimus. During the study, episodes of acute rejection and doses of glucocorticoids, cyclosporine, and tacrolimus were recorded.
Biochemical and Hormonal Determinations
Bone biochemical parameters including intact PTH measured by chemiluminescence method (Immulite), serum osteocalcin (OC), bone-specific alkaline phosphatase (BSAP), and urinary N-telopeptide (UNTx) were obtained at baseline and monthly for the next 12 mo. Blood levels of vitamin D were obtained at baseline and at 6 and 12 mo.
Bone Densitometry and Radiographic Studies
BMD of the vertebral spine (L1 to L4) and hip was measured at baseline and at 6 and 12 mo, using the same Hologic 4500 QDC scanner. Vertebral and hip radiographs were obtained at baseline and at 12 mo and evaluated for radiographic evidence of bone fractures.
Mineralized Histology and Bone Histomorphometry
Iliac bone samples were fixed in absolute ethanol, dehydrated, and embedded in methylmethacrylate as described previously (22). Serial sections of 3- and 7-µm thickness were cut with a Microm microtome, model HM360 (Carl Zeiss, Thornwood, NY). Three-micrometer-thick sections were stained with the modified Goldner Trichrome stain (23). Seven-micrometer-thick, unstained sections were prepared for phase contrast and fluorescence light microscopy and staining for detection of aluminum (24,25).
Histomorphometry of the bone was performed at a standardized site in deep cancellous bone. Static and dynamic parameters of bone structure, formation, and resorption were measured with the Osteoplan system II (Carl Zeiss, Thornwood, NY) (26,27). Histologic features were measured at a magnification of x200. All parameters used are in compliance with and were calculated according to the recommendations of the histomorphometry nomenclature committee of the American Society of Bone and Mineral Research (28). All samples were processed and analyzed in a similar manner and were evaluated in a blinded manner, i.e., without knowledge of treatment assignment.
Statistical Analyses
Power calculations were based on previously reported changes in vertebral BMD in renal transplant recipients (9). The power, set at 80% to detect an 8% difference in vertebral BMD in PAM versus CON at 12 mo, required a total of 60 participants.
Differences between PAM and CON groups were analyzed by t test. Paired t test detected differences in the same subject at two different time points. Independent t test compared the same time point in two different populations. ANOVA detected differences in parameters in more than three groups. In normally distributed results, multivariate linear regression analysis was used to determine which independent variables significantly influenced the dependent variable (change in vertebral BMD and percentage change in vertebral BMD at 6 and 12 mo). Independent variables included in the multivariate analyses were those that were significant on univariate analysis. The statistical program SPSS-8 was used to analyze the data. Means are reported as ± SD.
| Results |
|---|
|
|
|---|
No significant differences were found between the subjects who were randomized and those who were not randomized in terms of age, gender, race, and cause of ESRD and time on dialysis (Table 1). There were no adverse events related to the pamidronate infusion.
|
There was no significant difference in age, race, BMI, and time on dialysis between the two groups. There were more women in the control group (Table 2).
|
Biochemical and Hormonal Parameters
There were no significant differences between PAM and CON in baseline chemistries, vitamin D, PTH, BSAP, OC, and UNTx. Serum creatinine decreased significantly (P < 0.05) and similarly in both groups. Overall, no significant differences were observed between the two groups in serum calcium, phosphorus, bicarbonate, and magnesium. Likewise, no significant differences were found between the two groups in biochemical parameters of bone turnover and hormone levels at 6 and 12 mo (Table 3). There were no differences in baseline and at 6 and 12 mo in biochemical and hormonal parameters in patients who were treated with tacrolimus versus cyclosporine (data not shown).
|
Forty of the 55 subjects had bone densitometry at baseline and 6 mo, 50 subjects had bone densitometry at baseline and 12 mo, and 35 subjects had densitometries at baseline and at 6 and 12 mo. There was no difference in baseline measurements between the group that had two densitometries and the group that had all three studies.
Vertebral BMD
Vertebral BMD was higher at 6 mo in PAM than in CON (1.0345 ± 0.22 versus 0.8803 ± 0.12 g calcium/cm2; P < 0.017). The percentage decrease in vertebral BMD from baseline was significantly less in PAM as compared with CON (-0.63 ± 0.03 versus 4.6 ± 0.08%; P < 0.05; Figure 1).
|
Men in PAM showed a lesser decrease in vertebral BMD at 6 mo than men in CON (1.011 ± 0.12 versus 0.8975 ± 0.11 g/cm2; P < 0.036). Women in PAM tended to have preserved BMD as opposed to the women in CON (1.054 ± 0.28 versus 0.8583 ± 0.15 g/cm2; P < 0.064). Neither tacrolimus nor cyclosporine had a further effect on vertebral BMD in either PAM or CON.
Univariate analysis of covariates that were significantly associated with vertebral BMD at 6 mo included pamidronate use, creatinine at 6 mo, vitamin D 25, and BSAP. Those significant with the absolute change and percentage change at 12 mo included pamidronate use and race.
As the bone mineral densities were normally distributed at baseline and at 6 and 12 mo, multivariate linear regression analyses that included variables that were significant on univariate analysis were performed. Pamidronate use was significantly related to vertebral BMD at 6 mo (P < 0.015) as was BSAP (P < 0.029). Pamidronate use and race were significantly related to the percentage change of vertebral BMD at 6 and 12 mo (Table 4).
|
|
Bone Biopsy
Demographics.
Twenty-six subjects underwent living donor renal transplants; 21 had baseline bone biopsies (eight PAM, 13 CON); 14 had follow-up biopsies at 6 mo of protocol (six PAM, eight CON). The bone biopsy population was similar to the total nonbiopsy population in terms of gender, race, BMI, ESRD distribution, and biochemical parameters. The baseline biopsy subjects had had less time on dialysis (1.7 ± 2.2 versus 4.8 ± 3.9 yr). Similarly, the subjects who had follow-up bone biopsies were not different from the nonbiopsy population except for less time on dialysis (1.8 ± 2 versus 4.3 ± 4 yr, Table 5). They received standard immunosuppression with corticosteroids and cyclosporine or tacrolimus.
|
|
|
|
| Discussion |
|---|
|
|
|---|
Hip BMD did not change appreciably in either PAM or CON during the year of study. Both CON and PAM received vitamin D and calcium, which are commonly prescribed in patients who receive long-term steroid therapy for various underlying conditions (3,5,6). Vitamin D and calcium were not given in the previously reported trials of use of bisphosphonates in renal transplant recipients (18,19), possibly accounting for the decrease in hip BMD in their control groups during their study period. In addition, as the hip consists mainly of cortical bone, which has lower remodeling rates than the mainly cancellous bone found in the vertebrae, it may require a longer time of observation before any treatment differences can be detected.
Vertebral BMD results at 6 mo were corroborated by trends observed in changes in iliac crest bone volume and trabecular thickness at follow-up bone biopsies. The bone activity present at baseline was interpreted without the benefit of tetracycline to quantify the bone turnover so that baseline diagnoses were made on static parameters only. Nonetheless, we were able to distinguish among the various classifications of renal osteodystrophy on the basis of the presence and the quality of the cellular and architectural elements. This technique has been useful to classify renal osteodystrophy (22,29,30). The cellular parameters of bone formation and resorption (osteoclasts and osteoblasts number/bone length) revealed an impressive decline after 6 mo of pamidronate treatment. In CON, mean values of these parameters also fell but were less pronounced. These observations are in keeping with known effects of bisphosphonates on bone turnover (31) and the turnover-reducing effects of steroids (3,5). The histologic findings raise the concern of adynamic bone as a possible complication of the positive effects of pamidronate. Further studies are needed to determine whether this may reduce overall bone strength and thus increase the risk of fractures.
Standard biochemical parameters of bone metabolism such as UNTx, BSAP, and OC, although useful in monitoring bone health in the nonrenal transplant patient (32), did not predict bone activity or mineralization in the renal transplant recipient in our study. Because serum phosphorus levels were not different between PAM and CON, the observed findings do not seem to be a result of low phosphate levels.
PTH may affect vertebral BMD. In the nonrenal patient, PTH may have an anabolic effect on vertebral BMD and may increase measured density. Exogenous PTH may be useful in improving bone health in osteoporotic patients (33,34). In our study, PTH was similarly corrected in both PAM and CON, thus rendering an added influence of PTH on BMD unlikely.
The total amounts of immunosuppressive agents were similar in both groups, thus eliminating a specific effect of these drugs on BMD. Likewise, the total dose of corticosteroids was similar in both groups.
This study suggests that pamidronate can preserve vertebral BMD in renal transplant recipients when it is given prophylactically, at the time of renal transplantation. BMD continued to be maintained even after pamidronate was stopped, as compared with CON receiving vitamin D and calcium alone. It is likely to have a similar effect on hip BMD.
Loss of BMD is associated with increased fracture risk (35,36). Although the number of fractures at 12 mo was too small in our study to analyze, it would be expected that the better preserved vertebral BMD at 1 yr in PAM would be associated with decreased fracture risk. A recent study using the bisphosphonate ibandronate prophylactically in renal transplant recipients did not decrease the rate of vertebral fractures, although BMD increased (37). Of concern is the tendency toward very low bone turnover evidenced by bone histology at 6 mo in our study. We and others have reported that low PTH and presumably low bone turnover are associated with increased fractures in dialysis patients (38,39). Whether low bone turnover with increased bone density in these subjects treated with bisphosphonates carries the same risks associated with adynamic bone disease in dialysis patients is unclear (21).
That pamidronate is effective in preserving BMD is shown by the present study. Although the bone histology seems to have been affected by pamidronate, our study was not powered to detect differences on the effect that the bisphosphonate might have on bone turnover. Before our study, no data existed to demonstrate such an effect, so it was not possible to power the study to show a difference. In addition, because we did not have quantifiable measures of bone turnover because of lack of tetracycline double labeling on the baseline bone biopsies, we are not able to report a measured difference in bone turnover at the follow-up biopsy. Therefore, conclusions regarding the effect of bisphosphonates on renal transplant osteodystrophy cannot be reached on the basis of the histologic observations seen in our study but may serve as a basis of future investigation.
In summary, the present study demonstrates that bisphosphonate therapy in the adult with a new renal transplant is associated with preserved BMD and low bone turnover. Whether this therapy is useful in attenuating long-term bone loss of renal transplantation and decreasing bone fractures in this population of renal patients will require further study.
| Acknowledgments |
|---|
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
A. Qaseem, V. Snow, P. Shekelle, R. Hopkins Jr., M. A. Forciea, D. K. Owens, and for the Clinical Efficacy Assessment Subcommittee Pharmacologic Treatment of Low Bone Density or Osteoporosis to Prevent Fractures: A Clinical Practice Guideline from the American College of Physicians Ann Intern Med, September 16, 2008; 149(6): 404 - 415. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. MacLean, S. Newberry, M. Maglione, M. McMahon, V. Ranganath, M. Suttorp, W. Mojica, M. Timmer, A. Alexander, M. McNamara, et al. Systematic Review: Comparative Effectiveness of Treatments to Prevent Fractures in Men and Women with Low Bone Density or Osteoporosis Ann Intern Med, February 5, 2008; 148(3): 197 - 213. [Abstract] [Full Text] [PDF] |
||||
![]() |
U. Kunzendorf, B. K. Kramer, W. Arns, J. Braun, J. Grossmann, F. Pietruck, H. Schmidt-Gayk, A. Schwarz, E. Ziegler, H. Sperschneider, et al. Bone disease after renal transplantation Nephrol. Dial. Transplant., February 1, 2008; 23(2): 450 - 458. [Full Text] [PDF] |
||||
![]() |
M. Chonchol and R. P. Wuthrich Potential Future Uses of Calcimimetics in Patients with Chronic Kidney Disease NDT Plus, January 1, 2008; 1(suppl_1): i36 - i41. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Cunningham Bisphosphonates in the renal patient Nephrol. Dial. Transplant., June 1, 2007; 22(6): 1505 - 1507. [Full Text] [PDF] |
||||
![]() |
J. Cunningham Pathogenesis and Prevention of Bone Loss in Patients Who Have Kidney Disease and Receive Long-Term Immunosuppression J. Am. Soc. Nephrol., January 1, 2007; 18(1): 223 - 234. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. R. Weisinger, R. G. Carlini, E. Rojas, and E. Bellorin-Font Bone Disease after Renal Transplantation Clin. J. Am. Soc. Nephrol., November 1, 2006; 1(6): 1300 - 1313. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Mitterbauer, C. Schwarz, M. Haas, and R. Oberbauer Effects of bisphosphonates on bone loss in the first year after renal transplantation--a meta-analysis of randomized controlled trials Nephrol. Dial. Transplant., August 1, 2006; 21(8): 2275 - 2281. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Westenfeld, M. Ketteler, and V. M. Brandenburg Anti-RANKL therapy--implications for the bone-vascular-axis in CKD? Denosumab in post-menopausal women with low bone mineral density Nephrol. Dial. Transplant., August 1, 2006; 21(8): 2075 - 2077. [Full Text] [PDF] |
||||
![]() |
A. Djamali, M. Samaniego, B. Muth, R. Muehrer, R. M. Hofmann, J. Pirsch, A. Howard, G. Mourad, and B. N. Becker Medical Care of Kidney Transplant Recipients after the First Posttransplant Year Clin. J. Am. Soc. Nephrol., July 1, 2006; 1(4): 623 - 640. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Ketteler, G. Schlieper, and J. Floege Calcification and Cardiovascular Health: New Insights Into an Old Phenomenon Hypertension, June 1, 2006; 47(6): 1027 - 1034. [Full Text] [PDF] |
||||
![]() |
K. Olgaard and E. Lewin Can Hyperparathyroid Bone Disease Be Arrested or Reversed? Clin. J. Am. Soc. Nephrol., May 1, 2006; 1(3): 367 - 373. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Ohlrich, K. Barco, and M. R. Silver The Use of Parenteral Nutrition in a Severely Malnourished Hemodialysis Patient With Hypercalcemia Nutr Clin Pract, October 1, 2005; 20(5): 559 - 568. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Kananen, L. Volin, K. Laitinen, H. Alfthan, T. Ruutu, and M. J. Valimaki Prevention of Bone Loss after Allogeneic Stem Cell Transplantation by Calcium, Vitamin D, and Sex Hormone Replacement with or without Pamidronate J. Clin. Endocrinol. Metab., July 1, 2005; 90(7): 3877 - 3885. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. M. Maalouf and E. Shane Osteoporosis after Solid Organ Transplantation J. Clin. Endocrinol. Metab., April 1, 2005; 90(4): 2456 - 2465. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Lee, D. Glicklich, and M. Coco Pamidronate used to attenuate post-renal transplant bone loss is not associated with renal dysfunction Nephrol. Dial. Transplant., November 1, 2004; 19(11): 2870 - 2873. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
HOME
CURRENT ISSUE
ARCHIVES
JASN Express
ONLINE SUBMISSION
AUTHOR INFO
EDITORIAL BOARD SUBSCRIBE FEEDBACK ALERTS HELP |