Late Low-Dose Steroid Withdrawal in Renal Transplant Recipients Increases Bone Formation and Bone Mineral Density

Corticosteroids have been the most widely used immunosuppressive agents since the first clinical transplantation in the 1950s. There are few studies of late steroid withdrawal in renal transplantation and none have prospectively assessed bone mineral density (BMD). The study aim was to assess the impact of corticosteroid withdrawal, in stable renal transplant recipients, on BMD and bone turnover. BMD, osteocalcin (OC) and cross-linked telopeptide of type I collagen (CTx) were measured in 92 patients randomized into a trial of steroid withdrawal. Patients with functioning renal transplants for more than 1 year with a serum creatinine below 200 micromol/L entered the trial. All patients were on triple immunosuppression (Cyclosporin microemulsion, Azathioprine and prednisolone), corticosteroids were withdrawn at 1 mg/month. BMD was measured twice annually with serum CTx and OC. One year following withdrawal of glucocorticoids there was no significant difference in creatinine. BMD increased in the withdrawal group (2.54% per year L1-L4, p < 0.01), there was a slight reduction in the control group. Mean OC increased from 5.3 to 12.2 ng/mL (p < 0.05) in the withdrawal group, but was unchanged in the controls. No change was seen in CTx. Corticosteroid withdrawal in renal transplant recipients results in an increase in BMD with a corresponding increase in serum OC.     

Muscle Force and Bone Mineral Density after Parathyroidectomy and Subcutaneous Autotransplantation for Secondary Hyperparathyroidism

The object of this study was to determine the muscle force and bone mineral density (BMD) of patients with secondary hyperparathyroidism before and 3 months after operation. Thirty-nine patients with secondary hyperparathyroidism and regular dialysis were operated. Their ages were 47 ± 12 (mean ± SD) years and duration of dialysis was 70.5 ± 35.8 months. The clinical symptoms included bone pain in 23 patients (59%), skin itching in 21 (53.8%), general weakness in 13 (33.3%), conscious disturbance in 2, chest tightness in 1, and failure to thrive in 1. Total parathyroidectomy and autotransplantation of 60 mg of parathyroid gland into subcutaneous tissue was done routinely. BMD was measured in the lumbar spine (L2–L4) and left proximal femur, expressed as grams per square centimeter and as fracture risk. The extension force of the quadriceps muscle was measured at 60 degrees of right knee flexion, expressed as newtons (N) in a peak force and an average force. Three months after operation the BMD of the study group increased (in g/cm²) from 1.063 ± 0.181 to 1.148 ± 0.149 (p < 0.001) in L2–4 (n= 25), from 0.792 ± 0.14 to 0.875 ± 0.161 (p < 0.001), in femoral neck (n= 25), from 0.672 ± 0.171 to 0.754 ± 0.21 (p < 0.001) in Ward's triangle (n= 25), and from 0.69 ± 0.149 to 0.738 ± 0.143 (p < 0.001) in trochanter (n= 25). Fracture risk also was reduced significantly 3 months after operation at L2–4 (p= 0.003), femoral neck (p= 0.001), Ward's triangle (p= 0.003), and trochanter (p= 0.005). Muscle force (in newtons) increased from 264.8 ± 110.5 to 326 ± 110.9 (p= 0.023) in peak force (n= 18) and from 195.3 ± 90.4 to 258 ± 99 (p= 0.012) in average force (n= 18). The patients with general weakness had improved muscle force more prominently than those without general weakness. In addition to skin itching, bone pain, and soft tissue calcification, general weakness that causes disability is an indication for surgery in secondary hyperparathyroidism. After parathyroidectomy and autotransplantation, the muscle force tends to increase, especially in those with general weakness. An increment of BMD and reduction of fracture risk are also found after surgery.     

Increase in Bone Mineral Density after Successful Parathyroidectomy for Tertiary Hyperparathyroidism after Renal Transplantation

BACKGROUND: Few studies have reported changes of bone mineral density (BMD) after parathyroidectomy in patients with persistent hyperparathyroidism after renal transplantation (3 HPT). PATIENTS AND METHODS: We retrospectively analyzed 14 patients who underwent successful parathyroidectomy for 3 HPT and who had available BMD data before and after parathyroidectomy. RESULTS: Median follow-up time was 26 months (IQR: 16.8-40.2). Serum calcium levels decreased significantly after parathyroidectomy (2.32 +/- 0.09 versus 2.66 +/- 0.16 mmol/l; p < 0.01), as did PTH levels (5.1 +/- 3.0 versus 27.8 +/- 23.7 pmol/l; p < 0.01). Nine patients (64%) had a steroid-free immunosuppression at follow-up. Mean increase in BMD was 9.5 +/- 8.0% for the spine and 9.5 +/- 7.9% for the hip (p < 0.01 for both sites). Patients with osteoporosis (T-score 相似文献   

Postoperative Hungry Bone Syndrome in Patients with Secondary Hyperparathyroidism of Renal Origin

Background  

Hungry bone syndrome (HBS) is a postoperative condition of severe hypocalcemia that can be seen in patients who have undergone parathyroidectomy (PTX) for secondary hyperparathyroidism (2HPT) of renal origin. This study examines HBS in patients after PTX for 2HPT.     

Predictors of Bone Mineral Density Improvement in Patients Undergoing Parathyroidectomy for Primary Hyperparathyroidism

Introduction

Primary hyperparathyroidism (PHPT) results in increased bone turnover, resulting in bone mineral density (BMD) reduction and a predisposition towards fractures. Parathyroidectomy (PTX) is the only definitive cure.

Objective

The primary goals of this study were to investigate the impact of PTX on BMD in patients with PHPT and to identify factors associated with post-operative BMD improvement using a multivariate model.

Methods

Between 1999 and 2010, a total of 757 patients underwent PTX for treatment of PHPT; 123 patients had both a pre- and a post-operative dual-energy X-ray absorptiometry (DEXA) scan. A prospective database was queried to obtain information about patient demographics, medications, comorbidities, and pre- and post-operative laboratory values. A Cox regression model was used to stratify patients and to identify factors that independently predict BMD response following PTX in this patient population.

Results

Overall, mean percent change in BMD was +12.31 % at the spine, +8.9 % at the femoral neck (FN), and +8.5 % at the hip, with a mean follow-up of 2.3 ± 1.5 years. A total of 101 (82.1 %) patients had BMD improvement at their worst pre-operative site. In patients who improved, 69.9 % (n = 86) had >5 % increase. Factors associated with BMD improvement at the worst pre-operative site were as follows: male gender (hazard ratio [HR] 2.29; 95 % confidence interval [CI] 1.54–4.21); pre-operative BMD with T-score less than ?2.0 (HR 1.89; 95 % CI 1.11–2.39); age <55 years (HR 1.74; 95 % CI 1.14–2.25); BMD DEXA scan at >2.5 years post-operatively (HR 1.71; 95 % CI 1.09–2.17); history of previous fracture (HR 1.24; 95 % CI 1.05–1.92); and private insurance (HR 1.18; 95 % CI 1.06–2.1). The use of bisphosphonates, estrogens, vitamin D supplementation, or tobacco; obesity; history of previous PTX, serum calcium or parathyroid hormone levels were not independently associated with post-operative BMD improvement.

Conclusion

Osteoporosis is one of the established National Institutes of Health criteria for PTX in asymptomatic patients with PHPT, but BMD improvement is not consistently seen during the post-operative period. Gender, age, more severe pre-operative bone disease, and insurance status were all predictors for greater BMD improvement following PTX. Further studies with a rigorous post-operative BMD regimen are needed in order to validate these results.     

Recovery of Bone Mineral Density in 126 Patients after Surgery for Primary Hyperparathyroidism

Primary hyperparathyroidism (pHPT) is associated with increased fracture risk and decreased bone mass. The recovery of bone mass after surgery varies; therefore tests that predict the increase in bone mass after parathyroidectomy would be desirable. Preoperatively and at 1 year after surgery bone mineral content (BMC) in the distal radius and bone mineral density (BMD) in the lumbar spine and hip, as well as biochemical variables, were measured in 126 pHPT patients (95 women, 31 men). The mean ± SD age of the patients was 63 ± 15 years. The mean ± SD serum calcium level was 2.78 ± 0.16 mmol/L. Altogether, 60% of the patients had a low oral calcium intake, and 18% had a 25-hydroxyvitamin D₃ deficiency. Preoperatively, postmenopausal women had lower Z-scores for BMD in the hip (p < 0.001) and lumbar spine (p < 0.05) than did premenopausal women. One year after surgery the bone density had increased in about 50% of the patients. The multiple logistic regression analysis showed that there was a weak association between the change in BMD in the hip, the serum 1,25-dihydroxyvitamin D₃ level (p < 0.05), and renal function (p < 0.05), respectively. We concluded that about 50% of patients have increased bone mass after pHPT surgery, but the increase in the bone density is difficult to predict for the individual patient. Because many pHPT patients have low oral calcium intake and a vitamin D deficiency, it would be of interest to evaluate the role of postoperative calcium/vitamin D supplements.     

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.     

The Effect of Alendronate on Bone Mineral Disorder in Renal Transplant Patients

PurposeIn this study, we aimed to investigate the effect of long-term administration of alendronate to treat bone loss in renal transplant patients.MethodsEighty-two renal transplant recipients were divided into 3 groups. Group 1 included patients who were treated with calcium, vitamin D3, and alendronate; group 2 included patients who were treated with calcium and vitamin D3; and group 3 included patients who did not receive these medications. All patients' sociodemographic data, biochemical parameters, and bone mineral density (BMD) measurements were recorded.ResultsThere were no significant differences between sociodemographic and laboratory findings at the beginning of study in all groups. The BMD of lumbar spine and femoral neck was significantly less in group 1 at the beginning, 12 and 24 months of the study when compared with other group. At 12 and 24 months of the study, the BMD levels were decreased both group 2 and group 3, whereas in group 1, it was stable at 12 months and increased thereafter. In group 1, the initial femoral neck BMD was negatively correlated with parathormone, sex, and body mass index, and positively correlated with creatinine level. While there was a positive correlation between basal body mass index and femur neck BMD in group 2, there was no correlation between baseline parameters, demographic data, and bone mineral density in group 3 patients.ConclusionsIn conclusion, bone loss is inevitable despite calcium and vitamin D replacement. However, bone loss can be stopped and even reversed with alendronate therapy.     

Quantitative Ultrasound and Bone Mineral Density in Patients with Primary Hyperparathyroidism Before and after Surgical Treatment

The aim of this study was to assess the pattern of ultrasound (QUS) parameters and bone mineral density at different skeletal sites in patients with primary hyperparathyroidism (PHPT) before and after surgical treatment. In 22 patients (age range 28–74 years) with PHPT we measured speed of sound (SOS), attenuation (BUA) and Stiffness at the calcaneus, amplitude-dependent speed of sound (AD-SoS) at proximal phalanges, and bone mineral density at lumbar spine (BMD-LS) and at the mid-radius (BMD-MR) and ultradistal radius (BMD-UDR) before, 1 and 2 years after surgical operation. Twenty-two age- and sex-matched healthy subjects provided control data. Before surgery, all parameters apart from SOS were significantly lower in PHPT patients than in controls. At the end of the study period, BMD-LS increased by 7.0%, BMD-UDR by 7.4% and BMD-MR by 11.0%. The changes in ultrasound parameters after surgery were lower (0.44% for SOS, 2.2% for BUA, 3.3% for Stiffness and 2.6% for AD-SoS); however, the increase was statistically significant (p<0.05 and p<0.01, respectively) only for Stiffness and AD-SoS. Our results indicate that parathyroidectomy increases both axial and appendicular BMD and influences QUS parameters differently at the calcaneus and at the phalanges. The combined use of BMD and QUS could improve the assessment of skeletal status in patients with PHPT before and after surgery. Received: 22 January 1999 / Accepted: 25 August 1999     

Evaluation of Bone Mineral Density in Patients With Spinal Cord Injury

Abstract

Background/Objective: This study was performed to evaluate the bone mineral density (BMD) values in patients with spinal cord injury (SCI) and determine the effects of the level, severity, and duration of the neurological lesion and spasticity on BMD values.

Methods: A total of 75 patients with traumatic SCI and a healthy control group of 39 people were included in the study. The BMD values of the lumbar spine and 4 different regions of the hip (femoral neck, Ward's triangle, trochanter, and femoral shaft) of all cases were measured using dual energy x-ray absorptiometry. The biochemical markers were also analyzed.

Results: The BMD values in all measured regions were found to be decreased in patients compared with that of controls. The level and seventy of the lesion and the spasticity did not significantly affect BMD values in the regions analyzed. The BMD values of the hip decreased as the duration of SCI increased. The levels of plasma phosphorus and alkaline phosphatase, calcium in 24-hour urine samples, and the calcium/creatinine ratio in spot urines were found to be significantly higher in the patient group.

Conclusion: All patients with SCI had lower BMD values than controls. The level and severity of SCI and spasticity did not significantly affect BMD values. The BMD values of the hip decreased as the duration of SCI increased.     

Effect of Cinacalcet in Kidney Transplant Patients With Hyperparathyroidism

ObjectiveIn dialysis patients, cinacalcet could be an effective alternative to parathyroidectomy for treating hyperparathyroidism. In the present study, we aimed to determine the characteristics of subjects with persistent hyperparathyroidism who require parathyroidectomy despite the use of cinacalcet.MethodsNine kidney transplant patients (7 men, 2 women; mean age 53.2 [SD, 8.9] years) who had tertiary hyperparathyroidism were reviewed in a single center. Pre- and postcinacalcet levels of calcium, phosphorous, intact parathyroid hormone (iPTH), and renal function were analyzed to evaluate the effect of cinacalcet treatment in these patients. The baseline parameters before cinacalcet treatment were compared in patients who did and did not undergo parathyroidectomy.ResultsCinacalcet reduced serum calcium levels in all patients (11.48 [SD, 0.73] mg/dL to 10.20 [0.70] mg/dL; P = .008). Serum phosphorous levels significantly increased from 2.28 (SD, 0.77) mg/dL to 3.02 (SD, 0.65) mg/dL (P = .03). The iPTH levels in 7 patients decreased, while the mean level remained unchanged in total subjects. The iPTH levels increased even with cinacalcet treatment in 2 patients. In 3 patients, serum calcium levels abruptly increased after cinacalcet withdrawal. Five patients who showed persistent hypercalcemia due to hyperparathyroidism underwent parathyroidectomy. These 5 patients had significantly different characteristics compared with 4 patients who did not undergo parathyroidectomy: hypercalcemia (11.92 [SD, 0.68] mg/dL vs 10.93 [SD, 0.26] mg/dL; P = .02), hypophosphatemia (1.74 [SD, 0.36] mg/dL vs 2.95 [SD, 0.58] mg/dL; P = .03), and hyperparathyroidism (252.2 [SD, 131.4] pg/dL vs 101.5 [SD, 18.4] pg/dL; P = .02).ConclusionCinacalcet reduced hypercalcemia due to hyperparathyroidism in the transplant patients. However, patients who had pre-existing higher iPTH, hypercalcemia, and hypophosphatemia needed parathyroidectomy. Therefore, cinacalcet could be considered an alternative to parathyroidectomy in selected patients.     

Association of QCT Bone Mineral Density and Bone Structure With Vertebral Fractures in Patients With Multiple Myeloma

Computed tomography (CT) is used for staging osteolytic lesions and detecting fractures in patients with multiple myeloma (MM). In the OsteoLysis of Metastases and Plasmacell‐infiltration Computed Tomography 2 study (OLyMP‐CT) study we investigated whether patients with and without vertebral fractures show differences in bone mineral density (BMD) or microstructure that could be used to identify patients at risk for fracture. We evaluated whole‐body CT scans in a group of 104 MM patients without visible osteolytic lesions using an underlying lightweight calibration phantom (Image Analysis Inc., Columbia, KY, USA). QCT software (StructuralInsight) was used for the assessment of BMD and bone structure of the T₁₁ or T₁₂ vertebral body. Age‐adjusted standardized odds ratios (sORs) per SD change were derived from logistic regression analyses, and areas under the receiver operating characteristics (ROC) curve (AUCs) analyses were calculated. Forty‐six of the 104 patients had prevalent vertebral fractures (24/60 men, 22/44 women). Patients with fractures were not significantly older than patients without fractures (mean ± SD, 64 ± 9.2 versus 62 ± 12.3 years; p = 0.4). Trabecular BMD in patients with fractures versus without fractures was 169 ± 41 versus 192 ± 51 mg/cc (AUC = 0.62 ± 0.06, sOR = 1.6 [1.1 to 2.5], p = 0.02). Microstructural variables achieved optimal discriminatory power at bone thresholds of 150 mg/cc. Best fracture discrimination for single microstructural variables was observed for trabecular separation (Tb.Sp) (AUC = 0.72 ± 0.05, sOR = 2.4 (1.5 to 3.9), p < 0.0001). In multivariate models AUCs improved to 0.77 ± 0.05 for BMD and Tb.Sp, and 0.79 ± 0.05 for Tb.Sp and trabecular thickness (Tb.Th). Compared to BMD values, these improvements of AUC values were statistically significant (p < 0.0001). In MM patients, QCT‐based analyses of bone structure derived from routine CT scans permit discrimination of patients with and without vertebral fractures. Rarefaction of the trabecular network due to plasma cell infiltration and osteoporosis can be measured. Deterioration of microstructural measures appear to be of value for vertebral fracture risk assessment and may indicate early stages of osteolytic processes not yet visible. © 2014 American Society for Bone and Mineral Research.     

The Impact of Observation Versus Parathyroidectomy on Bone Mineral Density and Fracture Risk Determined by FRAX Tool in Patients With Primary Hyperparathyroidism

To study impact of observation (OBV) vs parathyroidectomy (PTX) on biochemistry, bone mineral density (BMD) and fracture risk calculated by Fracture Risk Assessment (FRAX) tool in primary hyperparathyroidism (PHPT). Retrospective study of 60 patients (OBV – 26; PTX – 34 patients). Mean adjusted calcium improved in both groups [OBV - 2.76 ± 0.07 vs 2.51 ± 0.20 mmol/L; p < 0.00001, PTX - 2.87 ± 0.21 vs 2.36 ± 0.12 mmol/L; p < 0.00001]. Mean parathyroid hormone level declined in both but more in PTX group [OBV - 11.4 ± 5.2 vs. 9.7 ± 5.6 pmol/L; p = 0.04, PTX - 14.3 ± 8.2 vs 4.6 ± 2.2 pmol/L; p < 0.00001]. In OBV group, BMD and T scores declined at all sites. Mean percentage change of BMD was -5.8 % at femoral neck (FN), -4.9 % at total hip (TH), -6.2 % at lumbar spine (LS) and -10.0 % at lower 1/3^rd radius (LR). PTX led to stabilization of BMD at FN (3.0 %), TH (-0.6 %) and LS (2.2 %) but significant improvement at LR (13.9 %; p = 0.0005). In OBV group, 10 year risk of hip fracture (HF) (7.5 ± 9.0 % vs. 8.6 ± 9.0; p = 0.01) and major osteoporotic fracture (OF) (16.6 ± 10.9 % vs 18.3 ± 10.8 %; p = 0.002) worsened with time whereas in PTX group, risk of both type of fractures remained stable (HF; p = 0.48 and OF; p = 0.43). Comparison between groups showed greater improvement in median % change of fracture risk for both HF and OF in PTX group. OBV in PHPT lead to greater decline in BMD at all skeletal sites and imparted significant risk of HF and major OF. PTX offered stabilization of BMD at most sites but improvement at LR with unchanged fracture risk. FRAX tool should be used more frequently and universally.     

Treatment With Cinacalcet of Secondary Hyperparathyroidism After Renal Transplantation

Background

The treatment of posttransplant secondary hyperparathyroidism (SHP) with vitamin D analogues is determined by their effectiveness to reverse hypercalcemia. Calcimimetics inhibit parathyroid hormone (PTH) secretion by modulating the calcium-sensing receptor in the parathyroid gland. Cinacalcet, a calcimimetic drug, has proven its effectiveness for the treatment of SHP among patients in phase V of chronic renal disease.

Patients and Methods

This retrospective analysis included 48 patients with SHP who were treated with cinacalcet. The initial dose of 30 mg/d could be increased to 180 mg, administering calcitriol also, depending on the serum calcium and PTH levels. The objectives were a PTH level between 75 and 125 pg/mL or a decrease >40%, and a serum calcium level below 10.5 mg/dL.

Results

The average PTH at baseline was 244 pg/mL, decreasing to 131 pg/mL at 1 year (P < .01). The average calcium at baseline was 10.1 mg/dL descending to 9.2 mg/dL at 1 year (P < .01). Among patients with hypercalcemia, the calcium decreased from 11 to 9.6 mg/dL at 1 year (P < .01). Seventy percent of patients without hypercalcemia reached the desired value of PTH, and 100% of those with hypercalcemia. Among patients with hypercalcemia, the desired calcium level was reached in 91% of cases. Ten patients developed hypocalcemia. In 3 cases we stopped the treatment with cinacalcet due to digestive intolerance.

Conclusions

Treatment with cinacalcet controlled hyperparathyroidism and hypercalcemia among patients with posttransplant SHP. It was a safe drug, with a low incidence of side effects.     

Osteoprotegerin and Bone Mineral Density in Hemodiafiltration Patients

A newly identified cytokine, osteoprotegerin (OPG) appears to be involved in the regulation of bone remodeling. In vitro studies suggest that OPG, a soluble member of the TNF receptor family of proteins, inhibits osteoclastogenesis by interrupting the intercellular signaling between osteoblastic stromal cells and osteoclast progenitors. As patients with chronic renal failure (CRF) often have renal osteodystrophy (ROD), we investigated the role of osteoprotegerin (OPG) in ROD, and investigated whether there was any relationship between serum OPG, intact parathyroid (PTH) (iPTH), vitamin D, and trabecular bone. Serum OPG combined with iPTH might be a useful tool in the noninvasive diagnosis of ROD, at least in cases in which the range of PTH values compromises reliable diagnosis. Thirty-six patients on maintenance hemodiafiltration (HDF) and a control group of 36 age and sex matched healthy subjects with no known metabolic bone disease were studied. The following assays were made on serum: iPTH, osteocalcin (BGP), bone alkaline phosphatase, 25(OH)-cholecalciferol, calcium, phosphate, OPG, IGF-1, estradiol, and free testosterone. Serum Ca^{+ +}, P, B-ALP, BGP, IGF-1, iPTH, and OPG levels were significantly higher in HDF patients than in controls, while DXA measurements and quantitative ultrasound (QUS) parameters were significantly lower. On grouping patients according to their mean OPG levels, we observed significantly lower serum IGF-1, vitamin D3 concentrations, and lumbar spine and hip bone mineral density in the high OPG groups. No correlation was found between OPG and bone turnover markers, whereas a negative correlation was found between serum OPG and IGF-1 levels (r= ? 0.64, p = 0.032). Serum iPTH concentrations were positively correlated with bone alkaline phosphatase (B-ALP) (r = 0.69, p = 0.038) and BGP (r = 0.92, p < 0.001). The findings made suggest that an increase in OPG levels may be a compensatory response to elevated bone loss. The low bone mineral density (BMD) levels found in the high OPG group might have been due to the significant decrease in serum IGF-1 and vitamin D3 observed. In conclusion, the findings made in the present study demonstrate that increased OPG in hemodiafiltration patients is only partly due to decreased renal clearance. As it may partly reflect a compensatory response to increased bone loss, this parameter might be helpful in the identification of patients with a marked reduction in trabecular BMD.