Osteoporosis and chronic kidney disease

The Effect of Hand Dominance, Age, Gender, Fracture Comminution and ASA Status on Time to Fracture Healing Following Surgical Fixation of Distal Radius Fractures

Background: There is recent renewed interest in the effect of hand dominance on distal radius fractures. Current studies focus on functional or patient-reported outcomes, with lack of studies pertaining to radiological outcomes. The primary aim of this study is to examine the effect of hand dominance on time to fracture healing following surgical fixation of distal radius fracture. We also looked at the effect of age, gender, fracture comminution and American Society of Anaesthesiologists (ASA) status on time to fracture healing.

Methods: Patients who underwent distal radius fracture fixation surgery in our department from 1 January 2015 to 31 December 2015 were included. Time to fracture healing was taken from the day of surgery to when radiographic union was present as evidence by bridging callus or osseous bone. We looked at the effect of hand dominance, age, gender, fracture comminution and ASA status on time to fracture healing.

Results: One hundred and forty-five consecutive patients (80 females and 65 males) had a mean period of 56.2 ± 41.8 days to fracture healing post-operatively. Patients with dominant hand injury had a shorter duration to fracture healing than patients with non-dominant hand injury (mean 47.3 ± 31.1 days versus 62.1 ± 46.8 days, p = 0.023). Patients ≥ 65 years and with pre-existing medical conditions (ASA Class II and above) had a longer duration to fracture healing (mean 63.7 ± 53.0 days versus 51.9 ± 33.4 days, p = 0.036 and mean 47.9 ± 30.0 days versus 62.0 ± 47.7 days, p = 0.016, respectively). In addition, patients with comminuted fractures took longer to heal than patients with non-comminuted fractures (mean 57.6 ± 33.4 days versus 48.3 ± 20.8 days, p = 0.038).

Conclusion: Time to fracture healing post distal radius fracture fixation surgery was significantly related to hand dominance, as well as age, ASA classification and fracture configuration. Dominant wrist injuries had shorter time to fracture healing.

Level of Evidence: Level IV (Therapeutic)

Renal impairment and time to fracture healing following surgical fixation of distal radius fracture

INTRODUCTION

Despite the prevalence of renal impairments, the existing literature examining fracture healing in the upper limb in patients with renal impairment is sparse. This study hence aims to investigate the effect of renal impairment on time to fracture healing after distal radius fracture fixation surgery.

MATERIALS AND METHODS

Patients above 50 years old who underwent distal radius fracture fixation via volar plating were included. Time to fracture healing was defined as duration between day of surgery and presence of radiographic union as evidence by bridging of callus or osseous bone. To assess for renal impairment, estimated glomerular filtration rate (eGFR) was calculated based on the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Pre-existing comorbidities were also collected and analysed.

RESULTS

Ninety-nine consecutive patients took mean 65.5 ± 8.0 days to fracture healing post-operatively. Patients with renal impairment had longer time to fracture healing than patients without (67.1 ± 50.4 days versus 50.4 ± 31.8 days, p = 0.044). Patients ≥ 65 years also had a longer duration to fracture healing compared to patients < 65 years (mean 63.7 ± 53.0 days versus 50.2 ± 27.2 days, p = 0.033). Similarly, patients with ASA Class I had a shorter mean time to fracture healing than patients with ASA Class II and above (mean 42.5 ± 22.8 days versus 62.8 ± 47.6 days, p = 0.028).

CONCLUSIONS

Time to fracture healing post-distal radius fracture fixation was significantly related to renal impairment, age and ASA classification.

Amniotic membrane mesenchymal stem cells-based therapy improves Bmi-1-deficient mandible osteoporosis through stimulating osteoblastic bone formation and inhibiting osteoclastic bone resorption

Mandible osteoporosis with age is characterized by greater fragility and accompanied with abnormal oral function. Mesenchymal stem cell transplantation can ameliorate osteoporosis. Bmi-1 is a transcriptional repressor which is an important regulator of cell cycle, stem cells self-renewal, and cell senescence. Here, we use a new kind of membrane mesenchymal stem cells (MSCs), amniotic membrane mesenchymal stem cells (AMSCs), to explore therapeutic effects on Bmi-1-deficient caused mandible osteoporosis. Phenotypes of mandibles from 5-week-old Bmi-1-deficient mice with AMSCs-based therapy were compared with age-matched Bmi-1-deficient mandibles without AMSCs-based therapy and wild-type mice. Bmi-1-deficient mice without AMSCs-based therapy displayed mandible osteoporosis accompanied with the rising senescence-associated molecules and imbalance redox homeostasis. Results showed that the alveolar bone volume, cortical thickness, type I collagen and osteocalcin immunopositive areas, mRNA expression levels of alkaline phosphatase, superoxide dismutase, gluathione reductase, and protein expression level of Runx2 were all reduced significantly in Bmi-1^-/- mandibles. Protein levels of PPARγ, p16, p21, p53, and redox gene levels of Bnip3l, Cdo1, Duox1, and Duox2 were up-regulated in mandibles from vehicle-transplanted Bmi-1^-/- mice. Also, osteoclasts were activated in Bmi-1^-/- alveolar bone. Transplanted AMSCs migrated into mandibles and improved all the parameters in Bmi-1^-/- mandibles with AMSCs-based therapy. These findings indicate that AMSCs-based therapy could rescue mandible osteoporosis induced by Bmi-1 deficiency through stimulating osteoblastic bone formation and inhibiting osteoclastic bone resorption. Our findings implied that AMSCs-based therapy had preventative and therapeutic potential for mandible osteoporosis.

Differential effects of jump versus running exercise on trabecular bone architecture and strength in rats

PURPOSE

This study compared differences in trabecular bone architecture and strength caused by jump and running exercises in rats.

METHODS

Ten-week-old male Wistar rats (n=45) were randomly assigned to three body weight-matched groups: a sedentary control group (CON, n=15); a treadmill running group (RUN, n=15); and a jump exercise group (JUM, n=15). Treadmill running was performed at 25 m/min without inclination, 1 h/day, 5 days/week for 8 weeks. The jump exercise protocol comprised 10 jumps/day, 5 days/week for 8 weeks, with a jump height of 40 cm. We used microcomputed tomography to assess microarchitecture, mineralization density, and fracture load as predicted by finite element analysis (FEA) at the distal femoral metaphysis.

RESULTS

Both jump and running exercises produced significantly higher trabecular bone mass, thickness, number, and fracture load compared to the sedentary control group. The jump and running exercises, however, showed different results in terms of the structural characteristics of trabecular bone. Jump exercises enhanced trabecular bone mass by thickening the trabeculae, while running exercises did so by increasing the trabecular number. FEA-estimated fracture load did not differ significantly between the exercise groups.

CONCLUSION

This study elucidated the differential effects of jump and running exercise on trabecular bone architecture in rats. The different structural changes in the trabecular bone, however, had no significant impact on trabecular bone strength.

Parathyroid hormone independently predicts fracture, vascular events, and death in patients with stage 3 and 4 chronic kidney disease

Doctors do not know whether treatment of high parathyroid hormone levels is linked to better outcomes in their patients with kidney disease. In this study, lower parathyroid hormone levels at baseline were linked to lower risk of fracture, vascular events, and death in people with kidney disease.

PURPOSE

Chronic kidney disease (CKD) affects ~ 20% of older adults, and secondary hyperparathyroidism (HPT) is a common condition in these patients. To what degree HPT predicts fractures, vascular events, and mortality in pre-dialysis CKD patients is debated. In stage 3 and 4 CKD patients, we assessed relationships between baseline serum PTH levels and subsequent 10-year probabilities of clinical fractures, vascular events, and death.

METHODS

We used Marshfield Clinic Health System electronic health records to analyze data from adult CKD patients receiving care between 1985 and 2013, and whose PTH was measured using a second-generation assay. Covariates included PTH, age, gender, tobacco use, vascular disease, diabetes, hypertension, hyperlipidemia, obesity, GFR, and use of osteoporosis medications.

RESULTS

Five thousand one hundred eight subjects had a mean age of 68 ± 17 years, 48% were men, and mean follow-up was 23 ± 10 years. Fractures, vascular events, and death occurred in 18%, 71%, and 56% of the cohort, respectively. In univariate and multivariate models, PTH was an independent predictor of fracture, vascular events, and death. The hazards of fracture, vascular events and death were minimized at a baseline PTH of 0, 69, and 58 pg/mL, respectively.

CONCLUSIONS

We found that among individuals with stage 3 and 4 CKD, PTH was an independent predictor of fractures, vascular events, and death. Additional epidemiologic studies are needed to confirm these findings. If a target PTH range can be confirmed, then randomized placebo-controlled trials will be needed to confirm that treating HPT reduces the risk of fracture, vascular events, and death.

High calcium, phosphate and calcitriol supplementation leads to an osteocyte-like phenotype in calcified vessels and bone mineralisation defect in uremic rats

A link between vascular calcification and bone anomalies has been suggested in chronic kidney disease (CKD) patients with low bone turnover disease. We investigated the vascular expression of osteocyte markers in relation to bone microarchitecture and mineralization defects in a model of low bone turnover CKD rats with vascular calcification. CKD with vascular calcification was induced by 5/6 nephrectomy followed by high calcium and phosphate diet, and vitamin D supplementation (Ca/P/VitD). CKD + Ca/P/VitD group (n = 12) was compared to CKD + normal diet (n = 12), control + normal diet (n = 8) and control + Ca/P/VitD supplementation (n = 8). At week 6, tibia, femurs and the thoracic aorta were analysed by Micro-Ct, histomorphometry and for expression of osteocyte markers. High Ca/P/VitD treatment induced vascular calcification only in CKD rats, suppressed serum parathyroid hormone levels and led to higher sclerostin, DKK1 and FGF23 serum levels. Expression of sclerostin, DKK1 and DMP1 but not FGF23 were increased in calcified vessels from CKD + Ca/P/VitD rats. Despite low parathyroid hormone levels, tibia bone cortical thickness was significantly lower in CKD + Ca/P/VitD rats as compared to control rats fed a normal diet, which is likely the result of radial growth impairment. Finally, Ca/P/VitD treatment in CKD rats induced a bone mineralization defect, which is likely explained by the high calcitriol dose. In conclusion, Ca/P/VitD supplementation in CKD rats induces expression of osteocyte markers in vessels and bone mineralisation anomalies. Further studies should evaluate the mechanisms of high dose calcitriol-induced bone mineralisation defects in CKD.

Declining Rates of Hip Fracture in End-Stage Renal Disease: Analysis From the 2003-2011 Nationwide Inpatient Sample

The incidence of hip fracture in patients with end-stage renal disease (ESRD) is considerably higher than that in the general age- and sex-matched population. Although medical therapy for chronic kidney disease mineral bone disorder (CKD-MBD) has changed considerably over the last decade, rates of hip fracture in the entire ESRD population have not been well-characterized. Herein, we evaluated temporal trends in rates of hip fracture, in-hospital mortality, and costs of associated hospital stay in ESRD. We identified hospitalizations for hip fracture from 2003 to 2011 using the Nationwide Inpatient Sample, a representative national database inclusive of all ages and payers. We incorporated data from the United States Renal Data System and the US Census to calculate population-specific rates. Between 2003 and 2011, we identified 47,510 hip fractures in the ESRD population. The overall rate of hip fracture was 10.04/1000 person-years. The rate was 3.73/1000 person-years in patients aged less than 65 years, and 20.97/1000 person-years in patients aged 65 or older. Age- and sex-standardized rates decreased by 12.6% from 2003 (10.23/1000 person-years; 95% confidence interval [CI], 7.99/1000 to 12.47/1000) to 2011 (8.94/1000 person-years; 95% CI, 7.12/1000 to 10.75/1000). Hip fracture rates over time were virtually identical in patients aged less than 65 years; however, rates decreased by 15.3% among patients aged 65 years or older; rates declined more rapidly in older women compared with older men (p for interaction = 0.047). In-hospital mortality rate after hip fracture operation declined by 26.7% from 2003 (8.6%; 95% CI, 6.8 to 10.4) to 2011 (6.3%; 95% CI, 4.9 to 7.7). In ESRD, age- and sex-standardized hip fracture rates and associated in-hospital mortality have declined substantially over the last decade. © 2017 American Society for Bone and Mineral Research.

The Use of Parenteral Nutrition in a Severely Malnourished Hemodialysis Patient With Hypercalcemia

There is a high prevalence of protein-energy malnutrition (PEM) in chronic dialysis patients. Causes of PEM include the catabolic effects of hemodialysis treatments, acidemia associated with end-stage renal disease, common comorbid conditions, and uremia-induced anorexia. Morbidity and mortality increase with PEM. Before considering parenteral nutrition (PN) as a nutrition intervention in a maintenance dialysis patient, all other efforts to promote optimal nutrition need to be exhausted. The first step is careful evaluation of protein-energy status, followed by intensive nutrition counseling. If necessary, this is followed by oral nutrition supplementation, appetite stimulation, enteral tube feedings, and finally PN. Short-term parenteral nutrition (PN) became a crucial component of the management of a 38-year-old hemodialysis (HD) patient who endured serious complications after kidney transplant rejection. A profound and prolonged malnourished state followed her treatment for necrotizing pancreatitis. She had developed persistent hypercalcemia believed secondary to tertiary hyperparathyroidism (HPT) and immobilization. Later, she developed hungry bone syndrome (HBS) after parathyroidectomy (PTX). She also developed refeeding syndrome after initiation of PN. The patient's persistent, poorly understood hypercalcemia did not resolve even after PTX and removal of all other sources of vitamin D and calcium from her feedings, medications, and dialysis bath. The close communication of the inpatient and outpatient dialysis multidisciplinary teams became a key component to the successful outcome in this complex patient.

Exercise Training Alters the Bone Mineral Density of Hemodialysis Patients

Marinho, SM, Moraes, C, Barbosa, JEdSM, Eduardo, JCC, Fouqe, D, Pelletier, S, and Mafra, D. Exercise training alters the bone mineral density of hemodialysis patients. J Strength Cond Res 30(10): 2918-2923, 2016-Patients with chronic kidney disease undergoing hemodialysis (HD) frequently present low bone mineral density (BMD), and exercise may be useful for treating bone loss. This study aimed to assess the effects of an intradialytic resistance exercise training program (RETP) on BMD in HD patients. Twenty-one patients were enrolled into 2 groups; 10 patients performed exercise (80.0% men; 46.9 ± 12.1 years; 27.0 ± 3.4 kg·m) and 11 patients were in the control group (54.5% men; 50.5 ± 11.5 years; 24.1 ± 8.7 kg·m). Dual-energy x-ray absorptiometry was used to measure the BMD, lean mass, and body fat before and after the supervised RETP (performed with elastic bands and ankle cuffs in both lower limbs 3 times a week for 24 weeks-72 sessions). In the exercise group, 30.0% of patients presented with osteopenia and 20.0% osteoporosis and in the control group, 45.5% osteopenia and 36.4% osteoporosis. Only in the exercise group, the osteoporosis percentage was reduced to 10.0% and the femoral neck BMD and T-score improved from 0.89 ± 0.1 to 0.93 ± 0.1 g·cm and from -1.3 ± 0.8 to -1.0 ± 0.8 g·cm (p ≤ 0.05), respectively, after the intervention. In contrast, these parameters were reduced in the control group. The results suggest that resistance exercise may be useful for improving the BMD in HD patients. In summary, 24 weeks of the supervised RETP played a role in improving the BMD of HD patients.

Hip Fracture in Patients With Non-Dialysis-Requiring Chronic Kidney Disease

Patients with end-stage renal disease (ESRD) are at a high risk for hip fracture. Little is known about the risk for, and consequences of, hip fracture among patients with non-dialysis-requiring chronic kidney disease (CKD). We examined the incidence of hip fracture, in-hospital mortality, length of stay, and costs among patients with ESRD, non-dialysis-requiring CKD, and normal or near normal kidney function. Using the Healthcare Cost and Utilization Project's Nationwide Inpatient Sample, a nationally representative database, we identified hospitalizations for hip fracture in 2010. We incorporated data from the United States Renal Data System (USRDS) and the US census to calculate population-specific rates. Age-standardized incidence of hip fracture was highest among patients with ESRD (3.89/1000 person-years), followed by non-dialysis-requiring CKD (1.81/1000 persons) and patients with normal or near normal kidney function (1.18/1000 persons). In-hospital mo rtality (odds ratio [OR] = 1.69, 95% confidence interval [CI] 1.46 to 1.96), lengths of stay (median [10th, 90th percentiles] 5 [3 to 11] versus 5 [3 to 10] days) and costs (median $14,807 versus $13,314) were significantly higher in patients with non-dialysis-requiring CKD relative to patients with normal or near normal kidney function. In summary, non-dialysis-requiring CKD is associated with higher age-standardized rates of hip fracture and post-hip fracture mortality and higher resource utilization. © 2016 American Society for Bone and Mineral Research.

Chronic kidney disease induced by adenine: a suitable model of growth retardation in uremia

Growth retardation is a major manifestation of chronic kidney disease (CKD) in pediatric patients. The involvement of the various pathogenic factors is difficult to evaluate in clinical studies. Here, we present an experimental model of adenine-induced CKD for the study of growth failure. Three groups ( n = 10) of weaning female rats were studied: normal diet (control), 0.5% adenine diet (AD), and normal diet pair fed with AD (PF). After 21 days, serum urea nitrogen, creatinine, parathyroid hormone (PTH), weight and length gains, femur osseous front advance as an index of longitudinal growth rate, growth plate histomorphometry, chondrocyte proliferative activity, bone structure, aorta calcifications, and kidney histology were analyzed. Results are means ± SE. AD rats developed renal failure (serum urea nitrogen: 70 ± 6 mg/dl and creatinine: 0.6 ± 0.1 mg/dl) and secondary hyperparathyroidism (PTH: 480 ± 31 pg/ml). Growth retardation of AD rats was demonstrated by lower weight (AD rats: 63.3 ± 4.8 g, control rats: 112.6 ± 4.7 g, and PF rats: 60.0 ± 3.8 g) and length (AD rats: 7.2 ± 0.2 cm, control rats: 11.1 ± 0.3 cm, and PF rats: 8.1 ± 0.3 cm) gains as well as lower osseous front advances (AD rats: 141 ± 13 μm/day, control rats: 293 ± 16 μm/day, and PF rats: 251 ± 10 μm/day). The processes of chondrocyte maturation and proliferation were impaired in AD rats, as shown by lower growth plate terminal chondrocyte height (21.7 ± 2.3 vs. 26.2 ± 1.9 and 23.9 ± 1.3 μm in control and PF rats) and proliferative activity index (AD rats: 30 ± 2%, control rats: 38 ± 2%, and PF rats: 42 ± 3%). The bone primary spongiosa structure of AD rats was markedly disorganized. In conclusion, adenine-induced CKD in young rats is associated with growth retardation and disturbed endochondral ossification. This animal protocol may be a useful new experimental model to study growth in CKD.

Calcimimetics for secondary hyperparathyroidism in chronic kidney disease patients

BACKGROUND

Calcimimetic agents lower abnormal serum parathyroid hormone (PTH) levels in people who have chronic kidney disease (CKD), but the benefits and harms on patient-level outcomes are uncertain. Since this review was first published in 2006 showing that evidence for calcimimetics was largely restricted to biochemical outcomes, additional studies have been conducted. This is an update of a review first published in 2006.

OBJECTIVES

To evaluate the benefits and harms of cinacalcet on patient-level outcomes in adults with CKD.

SEARCH METHODS

MEDLINE, EMBASE, CENTRAL and conference proceedings were searched for randomised controlled trials (RCTs) evaluating any calcimimetic against placebo or another agent in adults with CKD (persistent albuminuria > 30 mg/g with or without reduced glomerular filtration rate (GFR) (below 60 mL/min/1.73 m²)). We updated searches to 7 February 2013 including the Cochrane Renal Group's Specialised Register to complete this update.

SELECTION CRITERIA

We included all RCTs of a calcimimetic administered to patients with CKD for the treatment of elevated serum PTH levels.

DATA COLLECTION AND ANALYSIS

Data were extracted on all relevant patient-centred and surrogate outcomes. We summarised treatment estimates using random effects and expressed treatment effects as a risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

Eighteen studies (7446 participants) compared cinacalcet in addition to standard therapy with no treatment or placebo plus standard therapy. In adults with GFR category G5 (GFR below 15 mL/min/1.73 m²) treated with dialysis, routine cinacalcet treatment had little or no effect on all-cause mortality (RR 0.97, 95% CI 0.89 to 1.05), imprecise effects on cardiovascular mortality (RR 0.67, 95% CI 0.16 to 2.87), and prevented surgical parathyroidectomy (RR 0.49, 95% CI 0.40 to 0.59) and hypercalcaemia (RR 0.23, 95% CI 0.05 to 0.97), but increased hypocalcaemia (RR 6.98, 95% CI 5.10 to 9.53), nausea (RR 2.02, 95% CI 1.45 to 2.81) and vomiting (RR 1.97, 95% CI 95% CI 1.73 to 2.24). Cinacalcet decreased serum PTH (MD -281.39 pg/mL, 95% CI -325.84 to -234.94) and calcium (MD -0.87 mg/dL, 95% CI -0.96 to -0.77) levels, but had little or no effect on serum phosphorous levels (MD -0.23 mg/dL, 95% CI -0.58 to 0.12).Data were sparse for adults with GFR categories G3a to G4 (GFR 15 to 60 mL/min/1.73 m²) and kidney transplant recipients.Overall, based on GRADE criteria, evidence for cinacalcet in adults with GFR category G5 treated with dialysis (mortality, parathyroidectomy, hypocalcaemia, and nausea) is of high or moderate quality. High quality evidence suggests "further research is very unlikely to change our confidence in the estimate of treatment effect" and moderate quality evidence is "further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate". Information for adults with less severe CKD GFR category G3a to G4 is of low or very low quality. This means that further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate

AUTHORS' CONCLUSIONS

Routine cinacalcet therapy reduced the need for parathyroidectomy in adults treated with dialysis and elevated PTH levels but does not improve all-cause or cardiovascular mortality. Cinacalcet increases risks of nausea, vomiting and hypocalcaemia, suggesting harms may outweigh benefits in this population.

[Ethnicity and vitamin D]

Cohort studies, mainly US, show that vitamin D deficiency is more common in African-American population. Social and environmental factors play a role but the difference in skin color is essential. Despite low 25-hydroxyvitamin D concentrations, a lower risk of fragility or fracture exists in these populations. Vitamin D deficiency is a contributing factor in many chronic diseases. There is a relationship between vitamin D deficiencies, progression of chronic kidney disease and increased relative risk of mortality. If the ethnicity of patients is now taken into account to estimate renal function, probably specific recommendations for vitamin D deficiency are needed.

High phosphate feeding promotes mineral and bone abnormalities in mice with chronic kidney disease

BACKGROUND

Chronic kidney disease-mineral bone disorder (CKD-MBD) is a systemic syndrome characterized by imbalances in mineral homeostasis, renal osteodystrophy (ROD) and ectopic calcification. The mechanisms underlying this syndrome in individuals with chronic kidney disease (CKD) are not yet clear.

METHODS

We examined the effect of normal phosphate (NP) or high phosphate (HP) feeding in the setting of CKD on bone pathology, serum biochemistry and vascular calcification in calcification-prone dilute brown non-agouti (DBA/2) mice.

RESULTS

In both NP and HP-fed CKD mice, elevated serum parathyroid hormone and alkaline phosphatase (ALP) levels were observed, but serum phosphorus levels were equivalent compared with sham controls. CKD mice on NP diet showed trabecular alterations in the long bone consistent with high-turnover ROD, including increased trabecular number with abundant osteoblasts and osteoclasts. Despite trabecular bone and serum biochemical changes, CKD/NP mice did not develop vascular calcification. In contrast, CKD/HP mice developed arterial medial calcification (AMC), more severe trabecular bone alterations and cortical bone abnormalities that included decreased cortical thickness and density, and increased cortical porosity. Cortical bone porosity and trabecular number strongly correlated with the degree of aortic calcification.

CONCLUSIONS

HP feeding was required to induce the full spectrum of CKD-MBD symptoms in CKD mice.

Bone mineral density and fracture risk in older individuals with CKD

BACKGROUND AND OBJECTIVES

Kidney Disease Improving Global Outcomes guidelines recommend against bone mineral density (BMD) screening in CKD patients with mineral bone disease, due to a lack of association of BMD with fractures in cross-sectional studies in CKD. We assessed whether BMD is associated with fractures in participants with and without CKD in the Health, Aging, and Body Composition study, a prospective study of well functioning older individuals.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Hip BMD was measured by dual-energy x-ray absorptiometry. Osteoporosis was defined as a femoral neck BMD (FNBMD) T score below -2.5 and CKD as an estimated GFR <60 ml/min per 1.73 m(2). The association of BMD with incident nonspine, fragility fractures to study year 11 was analyzed using Cox proportional hazards analyses, adjusting for age, race, sex, body mass index, hyperparathyroidism, low vitamin D level, and CKD. Interaction terms were used to assess whether the association of BMD with fracture differed in those with and without CKD.

RESULTS

There were 384 incident fractures in 2754 individuals (mean age 73.6 years). Lower FNBMD was associated with greater fracture, regardless of CKD status. After adjustment, the hazard ratios (95% confidence intervals) were 2.74 (1.99, 3.77) and 2.15 (1.80, 2.57) per lower SD FNBMD for those with and without CKD, respectively (interaction P=0.68), and 2.10 (1.23, 3.59) and 1.63 (1.18, 2.23) among those with osteoporosis in patients with and without CKD, respectively (interaction P=0.75).

CONCLUSIONS

BMD provides information on risk for fracture in older individuals with or without moderate CKD.

The association of serum osteoprotegerin and osteoporosis in postmenopausal hemodialysis patients: a pilot study

AIM

Osteoprotegerin (OPG) is a potent inhibitor of osteoclasts and plays an important role in bone metabolism. Relatively high serum levels of OPG have been observed in postmenopausal women with osteoporosis compared with age-matched controls. No data, however, are available on the relationship between low bone density and serum OPG levels in postmenopausal hemodialysis (HD) patients.

METHODS

The enrolled subjects included 28 postmenopausal HD patients and 28 age-matched postmenopausal women with normal renal function as controls. Bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DEXA) in both hips. Low BMD was defined as femoral neck T-score <-2.5. Serum OPG levels were measured using a commercial enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

Eight of the age-matched postmenopausal controls (28.6%) and 12 of the postmenopausal HD patients (42.9%) had low BMD. There was no statistically significant difference in low BMD between postmenopausal HD patients and age-matched postmenopausal patients (p = 0.263). The serum OPG level was significantly higher in the postmenopausal HD group (p < 0.001). Increased serum OPG (p = 0.017) and decreased serum albumin (p = 0.021) were significantly correlated with low BMD in postmenopausal HD patients. Univariate linear regression analysis showed that serum albumin (r = -0.455, p = 0.015) was negatively correlated, whereas age (r = 0.423, p = 0.025) and the length of time since menopause (r = 0.397, p = 0.036) were positively correlated with the serum OPG level in postmenopausal HD patients. Multivariate forward stepwise linear regression analysis showed that serum OPG (adjusted R(2) = 0.262, p = 0.003) was an independent predictor of low BMD in postmenopausal HD patients and explained 26.2% of the variance.

CONCLUSIONS

Serum OPG is associated with low BMD in postmenopausal HD patients.

Chronic kidney disease in postmenopausal women

Menopause is derived from the Greek words men (month) and pauses (cessation) and means permanent cessation of menstruation after the loss of ovarian activity. Chronic kidney disease (CKD) has recently been associated with cardiovascular events in several studies. CKD patients have a heavy burden of traditional cardiovascular risk factors in addition to a range of nontraditional risk factors such as inflammation and abnormal metabolism of calcium and phosphate. In this review, the association of CKD and cardiovascular disease (CVD), as well as of osteoporosis in postmenopausal women is discussed. CKD mineral and bone disorder, characterized by disturbances of calcium/phosphate/parathyroid hormone, bone abnormalities and vascular and soft tissue calcification, is highly prevalent in CKD and is a strong, independent predictor of bone fracture, CVD and death. Estrogen has been shown to: (a) decrease the expression of angiotensin type 1 receptors in vasculature and kidneys; (b) reduce the expression and activity of angiotensin-converting enzyme, and (c) cause the release of angiotensinogen substrate from the liver. However, the degree of activation or suppression of the renin-angiotensin-aldosterone system by estrogen has not been clearly established. Clinical data on the effects of estrogen therapy on bone mineral densities are extremely limited in the ESRD population. CVD is the most common cause of death in postmenopausal women with CKD and many contributing factors have been explored. Future research for prevention of CVD in postmenopausal women with CKD would focus on the biology of vascular calcification as well as bone loss.

Comparison of rates and risk factors for development of osteoporosis and fractures after radical or partial nephrectomy

OBJECTIVE

To examine incidence of and risk factors for development of osteoporosis and fractures in patients who underwent radical nephrectomy (RN) and partial nephrectomy (NSS), as osteoporosis is an important cause of morbidity in chronic kidney disease.

METHODS

This was a retrospective review of 905 patients (mean age 57.5 years, mean follow-up 6.4 years) who underwent RN or NSS for renal tumors at 2 institutions from July 1987 to June 2007. Demographics, renal function, metabolic parameters, and history of preoperative and postoperative osteoporosis and fractures were recorded. Data were analyzed within subgroups based on treatment (RN vs NSS). Multivariate analysis was conducted to elucidate risk factors for developing osteoporosis following surgery.

RESULTS

A total of 610 patients underwent RN and 295 underwent NSS. Tumor size (cm) was significantly larger for RN (RN 7.0 vs NSS 3.7, P<.0001). No significant differences were noted with respect to demographic factors and preoperative osteoporosis (RN 8.7% vs NSS 9.5%, P=.785) and fractures (RN 1.7% vs NSS 0.7%, P=.382). Postoperatively, significantly less osteoporosis (NSS 12.5% vs RN 22.6%, P<.001) and fewer fractures (NSS 4.4% vs RN 9.8%, P=.007) developed in the NSS cohort. MVA demonstrated female (OR 1.85, P=.001), Caucasian (OR 2.33, P<.0001), preoperative eGFR<60 mL/min/1.73 m2, (OR=3.02, P<.0001), preoperative metabolic acidosis (OR=4.22, P=.0006), and RN (OR 2.59, P<.0001) were risk factors for developing osteoporosis.

CONCLUSIONS

Patients undergoing RN had a significantly higher incidence of osteoporosis and fractures compared with a well-matched cohort of patients who underwent NSS. In addition to RN, female gender, Caucasian background, preoperative eGFR<60, and preoperative metabolic acidosis were associated with developing osteoporosis.

Bone mineral densitometry in patients on hemodialysis: difference between genders and what to measure

INTRODUCTION

Chronic kidney disease (CKD) and osteoporosis are important health problems. There is an interrelationship between osteoporosis and CKD. Bone densitometry is the "gold" standard in the diagnosis of osteoporosis. Unfortunately, there are some problems with the interpretation of bone densitometry in CKD patients. The goal of this study was to determine bone mineral density (BMD) in CKD patients, to assess the difference between genders and different sites of bone densitometry correlation between BMD and laboratory parameters, and to assess the most optimal measuring site.

METHODS

We studied 134 hemodialysis (HD) patients (62 females, 72 males). The mean age was 56.4+/-12.4 years and the mean duration of HD was 54.4+/-60 months. BMD of the lumbar spine (posterior-anterior projection and lateral projection), hip (femoral neck, trochanter, intertrochanter, total femur, the Ward's Triangle), and forearm (ultradistal (UD), middistal (MID), distal third portion, and total forearm) was measured using dual X-ray absorptiometry (DXA) (Hologic Delphi apparatus). Values were expressed as BMD, T-score, and Z-score.

RESULTS

Females had lower values of BMD in all measurement points. There were no significant differences in T- and Z-scores of forearm between males and females. Age was in a positive correlation with lumbar spine BMD in males and females. There was a negative correlation with neck and forearm BMD in both groups. Serum parathyroid hormone (PTH) was also in negative correlation with hip and forearm BMD in both groups. The best correlation of BMD in different sites was between forearm and neck.

CONCLUSION

BMD data in CKD patients should be interpreted with caution and appendicular skeletal sites should be included in the evaluation.

Arterial and aortic valve calcification inversely correlates with osteoporotic bone remodelling: a role for inflammation

AIMS

Westernized countries face a growing burden of cardiovascular calcification and osteoporosis. Despite its vast clinical significance, the precise nature of this reciprocal relationship remains obscure. We hypothesize that cardiovascular calcification progresses with inflammation and inversely correlates with bone tissue mineral density (TMD).

METHODS AND RESULTS

Arterial, valvular, and bone metabolism were visualized using near-infrared fluorescence (NIRF) molecular imaging agents, targeting macrophages and osteogenesis. We detected significant arterial and aortic valve calcification in apoE(-/-) mice with or without chronic renal disease (CRD, 30 weeks old; n = 28), correlating with the severity of atherosclerosis. We demonstrated decreases in osteogenic activity in the femurs of apoE(-/-) mice when compared with WT mice, which was further reduced with CRD. Three-dimensional micro-computed tomography imaging of the cortical and cancellous regions of femurs quantified structural remodelling and reductions in TMD in apoE(-/-) and CRD apoE(-/-) mice. We established significant correlations between arterial and valvular calcification and loss of TMD (R(2) = 0.67 and 0.71, respectively). Finally, we performed macrophage-targeted molecular imaging to explore a link between inflammation and osteoporosis in vivo. Although macrophage burden, visualized as uptake of NIRF-conjugated iron nanoparticles, was directly related to the degree of arterial and valvular inflammation and calcification, the same method inversely correlated inflammation with TMD (R(2) = 0.73; 0.83; 0.75, respectively).

CONCLUSION

This study provides direct in vivo evidence that in arteries and aortic valves, macrophage burden and calcification associate with each other, whereas inflammation inversely correlates with bone mineralization. Thus, understanding inflammatory signalling mechanisms may offer insight into selective abrogation of divergent calcific phenomena.

Cardiovascular risk in chronic kidney disease (CKD): the CKD-mineral bone disorder (CKD-MBD)

Recent advances in our understanding of the excess mortality of chronic kidney disease (CKD) due to cardiovascular complications, obtained through observational studies, demonstrate that vascular calcification and hyperphosphatemia are major cardiovascular risk factors. Mechanistic studies demonstrate that these two risk factors are related and that hyperphosphatemia directly stimulates vascular calcification. The role of hyperphosphatemia in stimulating vascular calcification in CKD is associated with a block to the skeletal reservoir function in phosphate balance due to excess bone resorption. This has led to the realization that renal osteodystrophy is linked to vascular calcification by disordered mineral homeostasis (phosphate) and that a multiorgan system fails in CKD, leading to cardiovascular mortality. In children with renal disease, the multiorgan system fails, just as in adults, but the outcomes have been less well studied, and perceptions of differences from adults are possibly incorrect. Vascular calcification and cardiovascular mortality are less prevalent among pediatric patients, but they are present. However, CKD-induced vascular disease causes stiffness of the arterial tree causing, in turn, systolic hypertension and left ventricular hypertrophy as early manifestations of the same pathology in the adult. Because of the role of the skeleton in these outcomes, renal osteodystrophy has been renamed as the CKD mineral bone disorder (CKD-MBD). This review, which focuses on the pediatric patient population, describes our current state of knowledge with regards to the pathophysiology of the CKD-MBD, including the new discoveries related to early stages of CKD. As a new necessity, cardiovascular function issues are incorporated into the CKD-MBD, and new advances in our knowledge of this critical component of the disorder will lead to improved outcomes in CKD.

Hyperphosphatemia of chronic kidney disease

Observational studies have determined hyperphosphatemia to be a cardiovascular risk factor in chronic kidney disease. Mechanistic studies have elucidated that hyperphosphatemia is a direct stimulus to vascular calcification, which is one cause of morbid cardiovascular events contributing to the excess mortality of chronic kidney disease. This review describes the pathobiology of hyperphosphatemia that develops as a consequence of positive phosphate balance in chronic kidney disease and the mechanisms by which hyperphosphatemia acts on neointimal vascular cells that are stimulated to mineralize in chronic kidney disease. The characterization of hyperphosphatemia of chronic kidney disease as a distinct syndrome in clinical medicine with unique disordered skeletal remodeling, heterotopic mineralization and cardiovascular morbidity is presented.

Relationship between vitamin D status, parathyroid hormone levels and bone mineral density in patients with chronic kidney disease stages 3 and 4

AIM

Low vitamin D status is associated with secondary hyperparathyroidism and increased bone turnover in the general population and can aggravate the hyperparathyroidism of chronic kidney disease (CKD) patients. It is also correlated to low bone mineral density (BMD), but this correlation is less clear in CKD patients. Aims of our study were to investigate these associations in CKD stages 3 and 4 patients, and to identify significant predictors of BMD in this population.

METHODS

Serum 25-hydroxyvitamin D (25OHD) levels, BMD at the femur and radius, and bone mineral metabolism parameters were measured in 89 CKD stages 3 and 4 patients. Vitamin D status was defined according to the NKF/KDOQI guidelines.

RESULTS

Mean 25OHD levels were 53.8+/-32.1 nmol/L and correlated to the severity of proteinuria. Thirty-five patients (39%) had vitamin D insufficiency, 29 (33%) had vitamin D deficiency and five (6%) had severe deficiency. Of the 89 patients, two had osteoporosis and 31 had osteopenia either at femur or radius. Independent predictors for the total femur BMD were the intact parathyroid hormone (iPTH) levels and the body mass index (BMI). For the total radius BMD, independent predictor was only the BMI. Serum 25OHD levels were not directly associated with BMD, but they were independent predictors of iPTH.

CONCLUSION

Vitamin D insufficiency and deficiency are very common in CKD stages 3 and 4 population and may indirectly affect, via effects on iPTH, the BMD of these patients.

Increased risk of hip fracture among men with CKD

BACKGROUND

Patients with chronic kidney disease (CKD) have disturbances in mineral metabolism. Those requiring dialysis therapy are at substantially increased risk of fracture. However, fracture risk in patients with CKD not requiring dialysis has not been well studied.

STUDY DESIGN

Retrospective cohort.

SETTING & PARTICIPANTS

We identified men who sought care at 8 Veterans Affairs Medical Centers located in the Northwest from July 1999 to March 2006 who had a glomerular filtration rate (GFR) less than 60 mL/min/1.73 m(2). Patients who received long-term dialysis therapy or had a previous organ transplant, diagnosis of cancer, or history of hip fracture were excluded. Proportional hazards models were used to estimate the association of GFR stage with relative risk of hip fracture.

PREDICTOR

GFR estimated on the basis of 2 or more consecutively abnormal outpatient serum creatinine measurements during a 6-month period.

OUTCOME

Hip fracture ascertained from patient medical records.

RESULTS

In 33,091 veterans, 176 hip fractures were identified. After adjustment for age, body mass index, diabetes, and use of selected medications, relative risks of hip fracture for men with a GFR of 30 to 59 and 15 to 29 mL/min/1.73 m(2) were 1.28 (95% confidence interval, 0.88 to 1.66) and 3.98 (95% confidence interval, 2.25 to 7.74), respectively.

LIMITATIONS

Retrospective study of men only.

CONCLUSIONS

These results suggest that the risk of hip fracture in men with CKD stage 4 is increased to a degree similar to that of dialysis patients.

Osteoporosis and chronic kidney disease

Osteoporosis (OP), the most frequent bone disease affecting the general population, is associated with high fracture risk. Patients with impaired kidney function have bone and mineral disturbances leading to extraskeletal calcifications and complex changes in bone turnover that predispose them to increased fracture risk accompanied by increased morbidity and mortality. The combination of these two bone disorders seems to have an additive effect with regard to fracture risk and its outcome, so that appropriate diagnosis and treatment of this disorder should be of primary concern when approaching patients with kidney disease. Nevertheless, the clinical and laboratory diagnostic tools used to identify OP in the general population do not suit the requirement for detecting the complex bone and metabolic changes that occur with chronic kidney disease, leading to the lack of or the initiation of inappropriate therapy. This review will focus on the bone pathophysiologic processes involved in OP and renal osteodystrophy and address some of the problems associated with our current diagnostic tools and aspects of the therapeutic approaches.

Patient assessment in the diagnosis, prevention, and treatment of osteoporosis

Assessment of the patient with osteoporosis includes history and physical examination, laboratory testing, and imaging studies. Information gathered during this assessment assists clinicians in targeting strategies to prevent fractures. The medical history should contain items such as personal and family history of fractures, lifestyle, intake of substances such as vitamin D, calcium, corticosteroids, and other medications. The physical examination can reveal relevant information such as height loss and risk of falls. Bone mineral density (BMD), most commonly determined by dual-energy x-ray absorptiometry, best predicts fracture risk in patients without previous fracture. BMD testing is most efficient in women over 65 years old but is also helpful for men and women with risk factors. Serial BMD tests can identify individuals losing bone mass, but clinicians should be aware of what constitutes a significant change. Laboratory testing can detect other risk factors and can provide clues to etiology. Selection of laboratory tests should be individualized, as there is no consensus regarding which tests are optimal. Biochemical markers of bone turnover have a potential role in fracture risk assessment and in gauging response to therapy, but are not widely used at present. Clinicians should be aware of problems with vitamin D measurement, including seasonal variation, variability among laboratories, and the desirable therapeutic range. Careful assessment of the osteoporotic patient is essential in developing a comprehensive plan that reduces fracture risk and improves quality of life.

Osteoporosis in men: prevalence and investigation

In the past, osteoporosis was thought to affect only women; however, in the last decade it has become apparent that osteoporosis is common in men, particularly elderly men. Osteoporosis affects as many as 2 million men in the United States. Osteoporosis most commonly affects the hip and the lumbar vertebrae, but other bones, such as the radius, tibia, and ribs, may also fracture. The main feature of the etiology of the disease is that low bone mineral density results in increased susceptibility to bone fracture. The World Health Organization has defined osteoporosis as a bone mineral density T-score value >2.5 SDs below the mean observed in young adult women. Although the validity of this score for evaluating men has been questioned and it is not clear whether a male or female reference database should be used, it is nonetheless often used in this way. The disease affects men differently than women in a number of respects. It manifests itself later in life in men than in women, probably because men initially have greater bone mass. Mortality and morbidity associated with hip fractures are high in all elderly individuals, but they are substantially higher in men than in women. Unlike in women, there is an underlying cause for the osteoporosis in almost half of affected men. Thus, for elderly men, a complete history and physical examination may reveal some remediable conditions; treating these may stop further progression of the disease and prevent further morbidity or mortality. Corticosteroid therapy for arthritis or asthma is a common cause of osteoporosis in elderly men. Hypogonadism is a recognized cause of osteoporosis in men treated for carcinoma of the prostate with androgen withdrawal therapy; treatments to modify the effects of these agents on bone are available. Consumption of large amounts of alcohol will eventually result in osteoporosis in some elderly men. Moreover, alcohol can predispose confused elderly patients to falls and to fracture bones that are already osteoporotic. Hyperthyroidism is associated with a reduction in bone mineral density and an increased likelihood of bony fracture. A careful search for undiagnosed hyperthyroidism in elderly osteoporotic men may prove worthwhile. Vitamin D deficiency is common among older men and could contribute to an increase in fractures. Routine analyses of blood and biochemistry should be carried out in any older male patient with newly diagnosed osteoporosis. Dual x-ray energy absorptiometry should be performed on every new patient with newly diagnosed osteoporosis.

Association of kidney function with incident hip fracture in older adults

Kidney dysfunction is associated with bone loss, and patients with ESRD have an increased risk for hip fracture. However, the association of mild to moderate kidney disease with hip fracture has not been studied previously. The association of kidney function with incident hip fracture was examined among participants in the Cardiovascular Health Study, a community-based cohort of older individuals. The primary measure of kidney function was serum cystatin C, a measure that does not depend on lean mass. Hip fractures were identified using International Classification of Diseases, Ninth Revision codes for hospitalizations. A total of 4699 individuals had cystatin C measured in 1992 to 1993 and did not have a hip fracture before cystatin C measurement. The association of kidney function with hip fracture was analyzed with Cox proportional hazards models. Analyses were conducted separately for men and women. After a mean follow-up of 7.1 yr, 195 incident hip fractures occurred in women and 79 occurred in men. Higher cystatin C levels were associated with a higher risk for fracture in women (hazard ratio [HR] 1.26; 95% confidence interval [CI] 1.14 to 1.38 per SD) and in men (HR 1.27; 95% CI 1.11 to 1.46). After multivariable adjustment, higher cystatin C levels were significantly associated with hip fracture in women (HR 1.16; 95% CI 1.01, 1.33) but not in men (HR 1.14; 95% CI 0.86 to 1.52), although the magnitude of the association was similar. Kidney dysfunction, as assessed by cystatin C, is associated with an increased risk for hip fracture. Further studies are needed to evaluate potential mediators of this relationship and to assess whether interventions can decrease this risk.

Calcimimetics for secondary hyperparathyroidism in chronic kidney disease patients

BACKGROUND

Calcimimetic agents have recently been evaluated in the treatment of secondary hyperparathyroidism (SHPT) as add-on therapy to calcitriol and vitamin D analogues and dietary phosphate binders.

OBJECTIVES

To evaluate the benefits and harms of calcimimetics for the prevention of secondary hyperparathyroid bone disease (including osteitis fibrosa cystica and adynamic bone disease) in dialysis patients with chronic kidney disease (CKD).

SEARCH STRATEGY

MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and conference proceedings were searched for randomised controlled trials (RCTs) evaluating any calcimimetic against placebo or another agent in pre-dialysis or dialysis patients with CKD.

SELECTION CRITERIA

We included all RCTs of any calcimimetic agent, cinacalcet HCl (AMG-073, Sensipar), NPS R-467 or NPS R-568 administered to patients with CKD for the treatment of SHPT.

DATA COLLECTION AND ANALYSIS

Data were extracted on all relevant patient-centred and surrogate outcomes. Analysis was by a random effects model and results expressed as relative risk (RR) or weighted mean difference (MD) with 95% confidence intervals.

MAIN RESULTS

Eight studies (1429 patients) were identified, which compared a calcimimetic agent plus standard therapy to placebo plus standard therapy. The end of treatment values of parathyroid hormone (pg/mL) (MD -290.79, 95% CI -360.23 to -221.34), serum calcium (mg/dL) (MD -0.85, 95% CI -1.14 to -0.56), serum phosphorus (mg/dL) (MD -0.29, 95% CI -0.50 to -0.08) and the calcium by phosphorus product (mg(2)/dL(2))(MD -7.90, 95% CI -10.25 to -5.54) were significantly lower with calcimimetics compared to placebo. No significant effects on patient-based endpoints were demonstrated except for the risk of hypotension which was significantly reduced with calcimimetics compared to placebo (RR 0.53, 95%CI 0.36 to 0.79).

AUTHORS' CONCLUSIONS

Calcimimetic treatment of SHPT leads to significant improvements in biochemical parameters that observational studies have shown to be associated with increased mortality, cardiovascular risk and osteitis fibrosa, but patient-based benefits have not yet been demonstrated in trials. For patients with SHPT, the benefits of calcimimetics over standard therapy remain uncertain until further RCTs become available.

Osteoporosis in hemodialysis patients revisited by bone histomorphometry: a new insight into an old problem

Osteoporosis in hemodialysis patients is associated with high morbidity and mortality and, although extensively studied by noninvasive methods, has never been assessed through bone biopsy. The aim of this study was to use histomorphometry to evaluate osteoporosis and identify factors related to its development in hemodialysis patients. We conducted a cross-sectional study involving 98 patients (35 women and 63 men; mean age: 48.4 +/- 13 years) on hemodialysis for 36.9 +/- 24.7 months. Patients were submitted to transiliac bone biopsy with double tetracycline labeling. The bone metabolism factors ionized calcium, phosphorus, bone alkaline phosphatase, deoxypyridinoline, intact parathyroid hormone, and 25(OH) vitamin D were evaluated, as were the bone remodeling cytokines osteoprotegerin (OPG), soluble receptor-activator of NF-kappabeta ligand (sRANKL) and tumor necrosis factor-alpha (TNF)alpha. Osteoporosis was defined as trabecular bone volume (BV/TV) greater than 1 s.d. below normal (men <17.4%; women <14.7%). Forty-five patients (46%) presented osteoporosis, which was correlated with white race. We found BV/TV to correlate with age, OPG/sRANKL ratio, TNFalpha levels, and length of amenorrhea. In multiple regression analysis adjusted for sex and age, length of amenorrhea, white race, and OPG/sRANKL ratio were independent determinants of BV/TV. Histomorphometric analysis demonstrated that osteoporotic patients presented normal eroded surface and low bone formation rate (BFR/BS). Osteoporosis is prevalent in hemodialysis patients. Low BFR/BS could be involved in its development, even when bone resorption is normal. Cytokines may also play a role as may traditional risk factors such as advanced age, hypogonadism, and white race.

Kidney function predicts the rate of bone loss in older individuals: the Cardiovascular Health Study

BACKGROUND

Results of cross-sectional analyses of the association of kidney function with bone mineral density (BMD) have been conflicting. We examined the association of cystatin-C, a new marker of kidney function that is unrelated to lean mass, with initial and follow-up BMD, in an ancillary study of the Cardiovascular Health Study, a population-based cohort of individuals > or = 65 years old.

METHODS

Two years after measurement of cystatin-C and other covariates, the first BMD was measured in Pittsburgh, Pennsylvania and Davis, California, by using dual energy x-ray absorptiometry. Follow-up BMD was measured in Pittsburgh 4 years later. Associations of cystatin-C with initial BMD and the change in BMD (%/y) at the hip were examined with linear regression. Analyses were conducted separately for men and women.

RESULTS

In 1519 participants who had cystatin-C and initial BMD assessed, 614 had follow-up BMD. The percent annual change in BMD at the total hip by cystatin-C quartiles was -0.24, -0.13, -0.40, and -0.66%/y (first to fourth quartile) in women and -0.02, -0.30, -0.18, and -0.94%/y in men. After adjusting for potential confounders, cystatin-C was marginally associated with initial BMD in men but not women. Cystatin-C was associated with bone loss in men; after adjustment for weight loss, cystatin-C was not associated with bone loss in women.

CONCLUSION

Kidney dysfunction, as assessed by cystatin-C, is associated with a more rapid loss of BMD at the hip, especially in men. Further studies are needed to confirm these findings and to determine whether this loss leads to an elevated risk of fracture.

Meta-Analysis of Biochemical and Patient-Level Effects of Calcimimetic Therapy

BACKGROUND

Many randomized trials have now evaluated the effects of calcimimetics in patients with chronic kidney disease and secondary hyperparathyroidism (SHPT) on standard therapy with vitamin D and/or phosphate binders. We conducted a meta-analysis to evaluate outcomes of therapy with these novel agents.

METHODS

MEDLINE, EMBASE, the Cochrane Controlled Trials Register, and conference proceedings were searched for randomized controlled trials evaluating any calcimimetic against placebo or another agent in predialysis or dialysis patients with chronic kidney disease. Data were extracted for all relevant patient-centered and surrogate outcomes. Analysis was by means of a random-effects model, and results are expressed as relative risk or weighted mean difference (WMD) with 95% confidence intervals (CIs).

RESULTS

Eight trials (1,429 patients) were identified that compared a calcimimetic agent plus standard therapy with placebo plus standard therapy. End-of-treatment values for parathyroid hormone (4 trials; 1,278 patients; WMD, -290.49 pg/mL; 95% CI, -359.91 to -221.07), serum calcium (3 trials; 1,201 patients; WMD, -0.85 mg/dL; 95% CI, -1.14 to -0.56), serum phosphorus (3 trials; 1,195 patients; WMD, -0.29 mg/dL; 95% CI, -0.50 to -0.08), and calcium x phosphorus product (3 trials; 1,194 patients; WMD, -7.90 mg2/dL2; 95% CI, -10.25 to -5.54) were significantly lower with calcimimetic therapy compared with placebo. No significant effects on patient-based end points were shown.

CONCLUSION

Calcimimetic treatment of patients with SHPT leads to significant improvements in biochemical parameters that observational studies have associated with increased mortality, cardiovascular risk, and osteitis fibrosa, but patient-based benefits have not yet been shown. For patients with SHPT, the benefits of calcimimetics over standard therapy remain uncertain until additional randomized trials become available.

Risk factors for decreased total body and regional bone mineral density in hemodialysis patients with severe secondary hyperparathyroidism

Hyperparathyroidism contributes significantly to decreased bone mineral density (BMD) in end-stage renal disease patients, but this negative influence is not homogeneous throughout the skeleton. We studied the BMD by dual-energy X-ray absorptiometry on total body and on different regions of the skeleton in 42 patients with severe hyperparathyroidism on hemodialysis. We also evaluated the relationship between different risk factors and BMD found on the regions examined in these patients. The legs and other sites where cortical bone predominate were mostly affected, whereas trabecular bone was relatively preserved. This is probably the result of the different effects of hyperparathyroidism on cortical and trabecular bone, but we cannot rule out the interference of ectopic calcifications and sclerotic lesions of vertebral end-plates falsely increasing lumbar spine BMD. The main determinants of low total-body BMD were, in order of importance, immobility, high intact parathyroid hormone levels, low body mass index, and low albumin. Eleven patients presented with pathologic fractures, mainly in the legs, and BMD was lower in this group than in patients without fractures. In conclusion, our study makes clear that hyperparathyroidism is a great threat to bone density in hemodialysis patients, mainly in the legs, the site mostly affected by fragility fractures in our patients. Physicians must worry not only with high parathyroid hormone levels, but also with the nutritional state of these patients.