Osteoporosis in the elderly with chronic kidney disease

Effects of veverimer on serum bicarbonate and physical function in women with chronic kidney disease and metabolic acidosis: a subgroup analysis from a randomised, controlled trial

BACKGROUND

Globally, the prevalence of chronic kidney disease (CKD) is higher in women than in men; however, women have been historically under-represented in nephrology clinical trials. Metabolic acidosis increases risk of progressive loss of kidney function, causes bone demineralization and muscle protein catabolism, and may be more consequential in women given their lower bone and muscle mass. Veverimer, an investigational, non-absorbed polymer that binds and removes gastrointestinal hydrochloric acid, is being developed as treatment for metabolic acidosis.

METHODS

This was a Phase 3, multicenter, randomised, blinded, placebo-controlled trial in 196 patients with CKD (eGFR: 20-40 mL/min/1.73 m2) and metabolic acidosis who were treated for up to 1 year with veverimer or placebo. We present the findings from a pre-specified subgroup analysis evaluating the effects of veverimer on metabolic acidosis and physical function among women (N = 77) enrolled in this trial.

RESULTS

At week 52, women treated with veverimer had a greater increase in mean (± standard error) serum bicarbonate than the placebo group (5.4 [0.5] vs. 2.2 [0.6] mmol/L; P < 0.0001). Physical Function reported by patients on the Kidney Disease and Quality of Life - Physical Function Domain, a measure that includes items related to walking, stair climbing, carrying groceries and other activities improved significantly in women randomized to veverimer vs placebo (+ 13.2 vs. -5.2, respectively, P < 0.0031). Objectively measured performance time on the repeated chair stand test also improved significantly in the veverimer group vs. placebo (P = 0.0002).

CONCLUSIONS

Veverimer was effective in treating metabolic acidosis in women with CKD, and significantly improved how they felt and functioned.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03390842 . Registered on January 4, 2018.

Urgent surgery for spinal instability or neurological impairment caused by spinal brown tumors occurring in the context of end-stage renal disease

OBJECTIVE

Spinal instability or neurological impairment caused by spinal brown tumors (BTs) with end-stage renal disease (ESRD) is an acute condition that needs urgent surgery. There is not much published information on BTs of the mobile spine given the rarity of the disease, and the literature shows inconsistent treatment options and ambiguous follow-up information. The aim of the present study was to elucidate the clinical features, anesthesia management, and surgical treatment for this rare disease through long-term follow-up observations.

METHODS

Clinical, laboratory, radiological, and perioperative data on 6 consecutive patients with spinal BTs who had been admitted to the authors' institution between 2010 and 2016 were retrospectively reviewed. The literature on spinal BT with secondary hyperparathyroidism was also reviewed. Summaries of the clinical features and anesthesia management are provided.

RESULTS

The mean age of the 6 patients was 45.5 years (range 35-62 years). Lesions were located in the cervical segment (2 cases) and thoracic segment (4 cases). Localized pain was the most common complaint, and pathological fracture occurred in 5 patients. Elevation of serum alkaline phosphate (AKP) and parathyroid hormone (PTH) was a common phenomenon. Four patients underwent circumferential resection and 2 underwent laminectomy, with parathyroidectomy performed in all patients. The anesthesia process was uneventful for all patients. The mean follow-up was 33 months (range 26-40 months). No spinal lesion progression occurred in any patient. The Karnofsky Performance Status score improved to 80-90 by 3 months after surgery.

CONCLUSIONS

Although uncommon, spinal BTs should be a diagnostic consideration in patients with ESRD. The thoracic spine is the most frequently affected site. ESRD is not a contraindication for surgery; with the assistance of experienced anesthesiologists, urgent surgery is the preferred option to alleviate neurological impairment and restore spinal stability.

Aortic vascular calcification is inversely associated with the trabecular bone score in patients receiving dialysis

INTRODUCTION

Progressive chronic kidney disease (CKD) confers a marked increase in risk for vascular calcification, cardiovascular disease, fracture and mortality, with likely contributing factors including dysregulated bone metabolism and mineral homeostasis. In general population studies, increased vascular calcification is directly related to mortality and inversely related to bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA). In patients with CKD, abnormalities in turnover, mineralization and bone volume reduce the ability of DXA to predict fracture. The trabecular bone score (TBS) obtained from lumbar spine DXA images, provides a surrogate measure of microarchitectural integrity not captured by BMD. This study aimed to examine the association of the TBS to prevalent abdominal aortic calcification (AAC) in patients with CKD receiving dialysis.

METHODS

We performed a cross-sectional study of dialysis patients awaiting transplantation. All patients underwent laboratory testing, lateral spinal radiographs including the abdominal aorta, DXA imaging and TBS assessment. AAC scores were determined using the Kauppila method. Correlations and linear regression models were used to determine predictors of AAC scores.

RESULTS

146 patients (60% male, mean age 48 ± 13 years) were included, of whom 49% had prevalent calcification with an AAC score ≥ 1. Of those with calcification, the mean AAC score was 7 ± 5.5 and 42 patients had scores ≥ 6, considered to indicate severe AAC. TBS values corresponding to intermediate or high risk for fracture (<1.31) were present in 35% of patients. TBS values correlated inversely to AAC scores (β = -0.206, p = 0.013) and remained significant in multivariable linear regression, adjusting for age, BMI and time on dialysis (-0.160, p = 0.031). There was no significant correlation of AAC scores to any BMD parameter.

CONCLUSION

There is a high prevalence of AAC in relatively young dialysis patients awaiting transplantation and their AAC scores are inversely related to the TBS but not to DXA-derived BMD parameters. In patients with CKD on dialysis, TBS assessment reflects microarchitectural abnormalities of bone not captured by DXA. The inverse relationship of TBS to vascular calcification may provide insights into bone-vascular interactions in CKD.

Outcomes following surgical management of femoral neck fractures in elderly dialysis-dependent patients

INTRODUCTION

Proximal femur fractures are one of the most common fractures observed in dialysis-dependent patients. Given the large comorbidity burden present in this patient population, more information is needed regarding post-operative outcomes. The goal of this study was to assess morbidity and mortality following operative fixation of femoral neck fractures in the dialysis-dependent elderly.

METHODS

The full set of medicare data from 2005 to 2014 was retrospectively analyzed. Elderly patients with femoral neck fractures were selected. Patients were stratified based on dialysis dependence. Post-operative morbidity and mortality outcomes were compared between the two populations. Adjusted odds were calculated to determine the effect of dialysis dependence on outcomes.

RESULTS

A total of 320,629 patients met the inclusion criteria. Of dialysis-dependent patients, 1504 patients underwent internal fixation and 2662 underwent arthroplasty. For both surgical cohorts, dialysis dependence was found to be associated with at least 1.9 times greater odds of mortality within 1 and 2 years post-operatively. Blood transfusions within 90 days and infections within 2 years were significantly increased in the dialysis-dependent study cohort. Dialysis dependence alone did not contribute to increased mechanical failure or major medical complications.

CONCLUSION

Regardless of the surgery performed, dialysis dependence is a significant risk factor for major post-surgical morbidity and mortality after operative treatment of femoral neck fractures in this population. Increased mechanical failure in the internal fixation group was not observed. The increased risk associated with caring for this population should be understood when considering surgical intervention and counseling patients.

Osteoprotegerin and uremic osteoporosis in chronic hemodialysis patients

INTRODUCTION

Osteoprotegerin (OPG) is a powerful inhibitor of osteoclast activity, and it plays an important role in bone metabolism. In hemodialysis (HD) patients, the relationship between OPG and bone mineral density (BMD) is important, but remains unclear yet. The study objective was to assess the OPG role related to uremic osteoporosis in HD patients.

METHODS

This cross-sectional study has been realized on a cohort of 63 chronic HD patients.

INCLUSION CRITERIA

elderly prevalent HD patients with an age over 55 years old.

EXCLUSION CRITERIA

previous bone disease or previous renal transplant; neoplasia; parathyroidectomy, hormone replacement therapy. The data regarding demographical and clinical characteristics, including treatments for mineral and cardiovascular complications, were recorded. Serum OPG and mineral markers levels were measured. BMD was assessed by calcaneus quantitative ultrasound; it measured broadband ultrasound attenuation, speed of sound (SOS) and stiffness index (STI).

RESULTS

The high OPG levels were associated with higher bone mineral density (OPG-SOS P = 0.003; R = 0.37; OPG-STI P = 0.03; R = 0.28). Malnutrition, anemia and advanced age correlated with bone demineralization. Males had higher bone density parameters than females. In patients treated with vitamin D (P = 0.005), the BMD was increased comparing to patients without these treatments.

CONCLUSIONS

OPG levels had directly correlated with bone mineral density parameters. Our study further confirms the critical role of OPG in the pathogenesis of uremic osteoporosis in ESRD. Whether the increased circulant OPG protect against bone loss in patients undergoing HD remains to be established.

Inverse relationship of bone mineral density and serum level of N-terminal pro-B-type natriuretic peptide in peritoneal dialysis patients

Objective:

Chronic kidney disease is associated with decreased bone mineral density (BMD). In this study, the relationship between BMD and the fasting serum concentration of N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) was evaluated in peritoneal dialysis (PD) patients.

Material and Methods:

Fasting blood samples were obtained from 52 PD patients. BMD was measured by dual energy X-ray absorptiometry of the lumbar vertebrae (L2–L4). The serum NT-pro-BNP level was measured by an electrochemiluminescence immunoassay.

Results:

Ten patients (19.2%) had osteoporosis, 23 patients (44.2%) had osteopenia, and 19 patients had normal BMD. Increased serum NT-pro-BNP (p < 0.001), advanced age (p = 0.012), decreased body mass index (p = 0.006), body height (p = 0.018), and body weight (p = 0.004) were associated with lower lumbar T-scores, but sex, menopausal status, PD modality, diabetes mellitus, and hypertension were not. Multivariate forward stepwise linear regression analysis with adjustment for age, body height, body weight, body mass index, and log-NT-pro-BNP indicated that a high serum level of log-NT-pro-BNP (R² change = 0.346; p < 0.001) and low body weight (R² change = 0.208; p < 0.001) were significantly and independently associated with poor lumbar BMD.

Conclusion:

A high serum level of NT-pro-BNP and low body weight were associated with poor BMD in PD patients.

Effect of arteriovenous fistula and usage of arm with fistula on bone mineral density in hemodialysis patients

We aimed to determine the incidence of osteoporosis in hemodialysis patients, to evaluate the differences due to arteriovenous fistula on bone mineral density (BMD) and to investigate whether usage of arm with fistula has an effect on BMD. In this cross-sectional study, 96 patients with chronic renal disease undergone to dialysis were included. Place of fistula (radial and brachial) and dominant hand were recorded. All patients were asked to complete Likert's scale in order to determine the frequency of their usage of arm with fistula. Patients were assigned in two groups: age >51 and < 50 years. Age-matched control group included 60 subjects. BMD measurements were done on lumbar vertebra, femur and both forearms. BMD measurement of proximal femur and total radius were significantly lower in patients >50 years compared to healthy controls and bone density measurement of lumbar vertebra, proximal femur, 1/3 distal and total radius were significantly lower in patients < 50 years compared to healthy controls (p < 0.05). BMD measurement was significantly lower in arms with fistula, especially with radial fistula, compared to both arms without fistula and healthy controls (p < 0.05). When all patients were evaluated, BMD scores were lowering by increasing age, duration of dialysis and fistula and decreasing usage of arm with fistula. BMD in hemodialysis patients is lower than normal population. BMD of arm with fistula is lower than arm without fistula and healthy controls. Both radial and brachial fistula affect negatively ipsilateral BMD. Movement of arm with fistula has positive effects on BMD.

Evaluation of biochemical markers and bone mineral density in patients with chronic kidney disease stage 5D at the start of hemodialysis treatment

BACKGROUND

Patients with chronic kidney disease (CKD) have significant disorders of bone and mineral metabolism. In addition, they can also develop other bone disorders including osteoporosis. This study evaluated the bone mineral density (BMD) of patients at the start of hemodialysis treatment as well as the relationship between BMD and possible risk factors or biochemical markers.

METHODS

The study was performed in 82 patients (28 females, 54 males). BMD was measured by dual-energy X-ray absorptiometry (DXA) at the lumbar spine and the proximal femur.

RESULTS

We found a high prevalence of 25-hydroxyvitamin D deficiency (96%; mean levels 30.0 ± 17.7 nmol/L) and a reduction of BMD in comparison with gender- and age-matched normal population values at the total hip (Z-score = -0.31 ± 1.11) and the femoral neck (Z-score = -0.48 ± 1.16), but not at the lumbar spine (Z-score = 0.68 ± 1.81). The prevalence of T-scores ≤ -2.5 SD in the group of patients over 50 years was 52.0% in females and 33.3% in males. BMD positively correlated: with male gender and calcium levels at all measured sites, with age at the lumbar spine and with weight or BMI at the proximal femur.

CONCLUSION

CKD patients at the start of hemodialysis treatment had a high prevalence of low T-score values, corresponding to values for osteoporosis in the general population. BMD at the proximal femur was below the expected average for age and gender, but at the lumbar spine, BMD in hemodialysis patients was above average in persons without known CKD.

Association of bone mineral density with albuminuria and estimated glomerular filtration rate: the Dong-gu Study

BACKGROUND

Kidney dysfunction and albuminuria may be associated with BMD. However, little evidence has been reported on relationships between BMD and eGFR and albuminuria.

METHODS

A total of 8,992 subjects aged 50 years or older participated in a survey conducted. Participants had their lumbar spine and femoral neck BMD measured by a Lunar Prodigy bone densitometer (GE, Madison, WI). Kidney function was assessed using MDRD eGFR and diagnosis of albuminuria was based on albumin-creatinine ratio.

RESULTS

ACR was negatively associated with lumbar spine and femur neck BMD in females (lumbar spine: 1.001, 0.988, 0.974 and 0.979 g/cm(2), p < 0.001; femur neck: 0.796, 0.790, 0.783 and 0.782 g/cm(2), p = 0.002), but not in males, after adjusting for covariates. Additionally, eGFR was shown to be negatively associated with lumbar spine BMD after adjusting for covariates (male: 1.181, 1.166, 1.152 and 1.149 g/cm(2), p = 0.001; female: 0.997, 0.980, 0.979 and 0.982 g/cm(2), p = 0.005), but demonstrated no association with femur BMD.

CONCLUSIONS

ACR in females was negatively associated with lumbar spine and femur neck BMD, but not in males. eGFR was negatively associated with lumbar spine BMD in both males and females.

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.

Hospital admissions in elderly patients on chronic hemodialysis

BACKGROUND

The purpose of this study was to determine whether number of hospital admissions per patient per year (n/[pt-yr]) and hospital days per patient per year (d/[pt-yr]) differ between elderly and younger patients on chronic hemodialysis (HD).

PATIENTS AND METHODS

In a retrospective cohort analysis of incident HD patients in one dialysis unit over 15 years, we compared 166 HD patients older than 70 years (77.1 ± 4.7 yrs) at the onset of HD (group A) and 216 patients younger than 70 years both at onset (57.1 ± 7.6 yrs) and at the end of the HD period (group B). Eighty (48.2%) of group A and 141 (65.3%) patients of group B had diabetes mellitus.

RESULTS

No differences were noted in the overall hospitalization rate, presented as mean, {95% Confidence interval} (group A 2.40 {2.04-2.75}, group B 2.03 {1.89-2.16} n[pt-yr]) and days/[pt-year] (group A 33.6 {25.3-41.8}, group B 24.1 {18.9-29.23}). Group A had higher number of hospitalization days (P = 0.012) for surgery or trauma and higher rate (P = 0.045) and days (P = 0.041) of hospitalization for miscellaneous causes, primarily pulmonary disease, or malignancy. Among diabetic patients, group A had only a greater number of hospital days for cardiac disease (P = 0.050). Among patients without diabetes, group A had a higher number for hospital days for surgery or trauma (P = 0.027). All other univariate comparisons were not significant. Multiple linear regression identified comorbidity, quantified by the Charlson index, Caucasian race and poor compliance with the HD schedule as predictors of admission rate and days per year for vascular access issues and comorbidity, poor compliance, and advanced age at onset of HD as predictors of admission for causes other than vascular access related.

CONCLUSION

Hospitalizations, which affect quality of life, differ little between elderly and younger patients on HD. Therefore, hospitalizations do not constitute an argument for restricting access to HD to elderly patients.

Risk factors leading to reduced bone mineral density in hemodialysis patients with metabolic syndrome

Although metabolic syndrome (MS) is associated with low bone mineral density (BMD) in the general population, it is unknown whether similar associations exist in patients with chronic kidney disease. We investigated risk factors that can lead to low BMD values in hemodialysis patients with MS according to the diagnostic criteria set by International Diabetes Federation (IDF) in this study. A total of 64 patients with MS undergoing hemodialysis and 60 hemodialysis patients who were matched in terms of age, gender, and hemodialysis duration without MS were enrolled in the study. BMD was measured at lumbar vertebra (LV) and femur neck (FN) by performing dual-energy X-ray absorptiometry (DEXA). LV and/or FN-BMD results revealed that, of the hemodialysis patients with MS, 45% had osteoporosis and 48% had osteopenia. On the other hand, of the hemodialysis patients without MS, 42% had osteoporosis and 52% had osteopenia. Low BMD values were observed to be correlated negatively with age, hemodialysis period, and parathormone (PTH) both in the group with MS and in the group without MS. Height, weight, BMI, calcium, phosphorus, alkaline phosphatase, heparin, and vitamin D therapy and urea reduction ratio were not established to be correlated with BMD.

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.

Bone mineral density and parathyroid function in patients on maintenance hemodialysis

BACKGROUND

The relationship between parathyroid function, an important determinant of bone turnover, and bone mineral density (BMD) in patients with chronic kidney disease is not fully understood. We wanted to analyze the association between BMD and parathyroid function in hemodialysis patients in details.

METHODS

In a cross-sectional design, data from 270 patients (age 55 ± 15 years, 60% men, all Caucasian) on maintenance hemodialysis were analyzed. All patients underwent dual energy X-ray absorptiometry of the lumbar spine (LS), femoral neck (FN) and distal radius (DR). In addition to routine laboratory tests, blood samples were collected for iPTH, serum markers of bone metabolism (alkaline phosphatase, type I collagen crosslinked-C-telopeptide) and 25OH vitamin D.

RESULTS

Based on Z-scores, bone mineral density was moderately reduced only at the femoral neck in the total cohort. The average Z-score of the "low PTH" group (iPTH < 100 pg/ml) was not different from the Z-score of patients with iPTH in the "target range" (100-300 pg/ml) at any measurement site. While iPTH was negatively correlated with BMD at all measurement sites in patients with iPTH > 100 pg/ml (rho = -0.255, -0.278 and -0.251 for LS, FN and DR, respectively, P < 0.001 for all), BMD was independent of iPTH in patients with iPTH < 100 pg/ml. Furthermore, iPTH was not associated with serum markers of bone metabolism, but these markers were negatively correlated with BMD in the "low PTH" group.

CONCLUSIONS

Low PTH levels are not associated with low BMD in patients with end-stage kidney disease. Furthermore, bone metabolism seems to be independent of iPTH in patients with relative hypoparathyroidism likely reflecting skeletal resistance to PTH.

Arteriovenous fistula affects bone mineral density measurements in end-stage renal failure patients

BACKGROUND AND OBJECTIVES

Hemodialysis needs an arteriovenous fistula (AVF) that may influence the structure and growth of nearby bone and affect bone mass measurement. The study analyzed the effect of AVF in the assessment of forearm bone mineral density (BMD) measured by dual energy x-ray absorptiometry (DXA) and examined its influence on the final diagnosis of osteoporosis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Forty patients (52 +/- 18 yr) in hemodialysis program (12 +/- 8 yr) with permeable AVF in forearm were included. Patients were divided in two groups (over and under 50 yr). BMD of both forearms(three areas), lumbar spine, and femur was measured by DXA. Forearm measurements in each arm were compared. Patients were diagnosed as normal only if all territories were considered nonpathologic and osteoporosis/osteopenia was determined by the lowest score found.

RESULTS

Ten patients were excluded and 30 patients were analyzed. BMD in the forearm with AVF was significantly lower than that observed in the contralateral forearm in both groups of patients and in all forearm areas analyzed. When only lumbar spine and femur measurements were considered, 70% of patients were nonpathologic and 30% were osteoporotic. However, inclusion of AVF forearm classified 63% as osteoporotic and a further 27% as osteopenic, leaving only 10% as nonpathologic.

CONCLUSIONS

Forearm AVF affects BMD measurements by decreasing their values in patients with end-stage renal failure. This may produce an overdiagnosis of osteoporosis, which should be taken into account when evaluating patients of this type.

Spinal surgery in patients with end-stage renal disease undergoing hemodialysis therapy

STUDY DESIGN

Case series retrospective review.

OBJECTIVE

To present the surgical treatment guideline for spinal diseases with end-stage renal disease (ESRD) patients undergoing hemodialysis.

SUMMARY OF BACKGROUND DATA

Treatment for spinal diseases with ESRD patients in is a special clinical challenge because of complex medical and clinical problems.

METHODS

We retrospectively reviewed 12 patients who underwent spinal surgeries among patients with chronic renal failure at our hospital from May 2000 to September 2007. The medical records and radiologic findings for these patients were reviewed and concomitant medical diseases, laboratory findings, pre- and postoperative care, clinical outcomes, and complications were investigated.

RESULTS

One patient died of pneumonia and sepsis 2 months after fusion surgery. Other postoperative complications included postoperative delirium in 3 patients and terminal ileitis and delayed primary spondylodiscitis in 1 patient each. There were no postoperative wound infections associated with the spinal surgery.The preoperative mean visual analogue scale score was 7.9 +/- 0.61, which improved to 2.2 +/- 1.25 at the time of final follow-up for 11 patients. Among 5 patients who underwent fusion surgery, solid bone fusion was achieved in only 3 patients and included those who underwent posterior lumbar interbody fusion with pedicle screw fixation. In 2 patients who underwent posterior lumbar interbody fusion with cage alone, solid fusion was not achieved. In 1 of 2 patients who underwent anterior cervical fusion with plating, solid fusion was achieved. The overall fusion rate was 57.1% in patients with ESRD undergoing hemodialysis.

CONCLUSION

Spinal surgeries in ESRD patients undergoing hemodialysis can be performed with acceptable outcomes; however, the complication rates and mortality rates are relatively high and the fusion rate is low. To obtain a better outcome, multiple factors such as comorbid medical diseases, laboratory abnormalities, and osteoporosis should be carefully considered.

Natural history of CKD stage 4 and 5 patients following referral to renal management clinic

BACKGROUND

CKD patients referred to a renal management clinic are looked after by a multidisciplinary team whose care may improve outcome and delay the progression of kidney disease. This paper describes our experience and the results obtained in 940 patients with CKD stage 4 and 5 patients from two renal management clinics (RMC).

SUBJECTS AND METHODS

We collected and analyzed the data from 940 patients with CKD stage 4 and 5 at the RMCs of the Toronto General Hospital (TGH), University Health Network and The Scarborough General Hospital (TSH) from January 2000 to November 2007. Inclusion criteria for the study required at least three measurements of serum creatinine over a minimum follow-up of 6 months. We calculated the change of slope of the estimated GFR by linear regression analysis. The slopes were further subdivided into five groups: improved eGFR (eGFR slope >or=+5 ml/min/year); mild improvement (slope >+1 to <+5 ml/min/year); stable (slope <+1 to >-1 ml/min/year); slow progression (i.e., deterioration; slope <-1 to >-5 ml/min/year) and rapid progression (slope >-5 ml/min/year).

RESULTS

During a median follow-up of 1.57 year (range 0.5-8.7 year) of stage 4 patients, eGFR improved in 10.6%, showed mild improvement in 24.2%, was stable in 27.5%, showed slow progression in 28.8% and rapid progression in 8.9% of patients. During a median follow-up of 1.4 year (range 0.5-8 year) of CKD stage 5 patients, eGFR improved in only 1.3%, showed mild improvement in 4.3%, remained stable in 35.6%; showed slow progression in 19.7% and rapid progression in 39.1%. Between the two hospitals (TGH and TSH) there was a statistically significant difference in the number of visits per year for CKD stage 4 patients during the first, second and third year. However, the number of visits per year had no effect on the rate of decline. On univariate analysis, factors predicting non-progression in eGFR slope were eGFR at referral, the use of ACE inhibitors-ARBs and absence of cardiovascular disease. However, in logistic multivariate regression analysis, after adjusting for confounding factors only the eGFR at referral and ACE inhibitors-ARBs were independent factors for non-progression in eGFR. A significant percentage of CKD stage 4 patients attending a renal management clinic (RMC) showed non-progression or improvement in their kidney function. Although only few stage 5 CKD patients had improvement in their eGFR, 32% of them maintained their eGFR on conservative treatment for over 2 years delaying the initiation of dialysis.

Bone imaging and chronic kidney disease: will high-resolution peripheral tomography improve bone evaluation and therapeutic management?

Bone damage because of chronic kidney disease (CKD) represents a daily challenge for nephrologists. The impact of CKD on bone health may be immediate (serum phosphocalcic disturbances) or delayed (bone fractures and vascular calcifications). Histomorphometry remains the gold standard to evaluate bone, but it is rarely performed in clinical practice. Areal measurement of bone mineral density by dual x-ray absorptiometry is routinely performed to evaluate bone mass. However, this technique presents some limitations. In 2000, the United States National Institutes of Health defined new "quality" criteria for the diagnosis of osteoporosis in addition to decreased bone mass. Bone strength actually integrates two concepts: bone quantity and bone quality (i.e., microarchitectural organization, bone turnover, bone material properties such as mineralization, collagen traits, and microdamage) that cannot be evaluated by dual x-ray absorptiometry. New three-dimensional, noninvasive bone-imaging techniques have thus been developed, e.g., high-resolution peripheral quantitative computed tomography. High-resolution peripheral quantitative computed tomography allows evaluation of both volumetric density and microarchitecture in different compartments of bone, at the distal radius and tibia. High-resolution peripheral quantitative computed tomography may be useful in predicting fractures and assessing bone preventive or therapeutic strategies in CKD patients. It should be evaluated in long-term, longitudinal follow-ups.

Magnesium metabolism in health and disease

Magnesium (Mg) is the main intracellular divalent cation, and under basal conditions the small intestine absorbs 30-50% of its intake. Normal serum Mg ranges between 1.7-2.3 mg/dl (0.75-0.95 mmol/l), at any age. Even though eighty percent of serum Mg is filtered at the glomerulus, only 3% of it is finally excreted in the urine. Altered magnesium balance can be found in diabetes mellitus, chronic renal failure, nephrolithiasis, osteoporosis, aplastic osteopathy, and heart and vascular disease. Three physiopathologic mechanisms can induce Mg deficiency: reduced intestinal absorption, increased urinary losses, or intracellular shift of this cation. Intravenous or oral Mg repletion is the main treatment, and potassium-sparing diuretics may also induce renal Mg saving. Because the kidney has a very large capacity for Mg excretion, hypermagnesemia usually occurs in the setting of renal insufficiency and excessive Mg intake. Body excretion of Mg can be enhanced by use of saline diuresis, furosemide, or dialysis depending on the clinical situation.

The impact of sex hormone changes on bone mineral deficit in chronic renal failure

In chronic renal failure several factors affect bone homeostasis leading to the development of renal osteodystrophy. Common calcitropic hormone derangements in renal failure play a central role in bone structure and mineral defects, which in turn accompany osteodystrophy frequently resulting in low bone mineral density (BMD) values. However, patients with end-stage renal disease (ESRD) suffer from several comorbidities, which may partly account for renal bone disease lesions. Hypogonadism in particular accompanies chronic renal failure frequently and exerts an additive effect on bone loss potential. Sex hormones contribute to the equilibrium of osteotropic hormones and cytokines, exerting a protective action on bone tissue. Estrogens have a regulatory effect on bone metabolism in women with renal failure as well. Hypogonadal ESRD women experience a higher bone turnover and more significant bone mass decrements than ESRD women with relatively normal hormone profile and menstrual habits. Female hemodialysis patients have lower BMD values than male patients on average, probably because of menstrual cycle irregularities. However, hypogonadal ESRD men may also experience bone mineral deficits and the severity of hypogonadism may correlate to their bone mineral status. Hormone replacement therapy (HRT) appears to reverse bone mineral loss to some extent in both sexes. In conclusion hypogonadism in renal failure contributes to the bone structure and mineral defects as well as the low-energy fracture risk, reflected in BMD measurements. HRT in ESRD patients should therefore not be overlooked in these patients in the face of their significant comorbidities.

The effect of peritoneal dialysate on DXA bone densitometry results in patients with end-stage renal disease

The bone mineral density of patients undergoing peritoneal dialysis (PD) is low compared to a healthy population. No studies have been conducted to investigate whether the presence of peritoneal dialysate affects dual-energy X-ray absorptiometry (DXA) results. We hypothesized that the presence of peritoneal dialysate would not affect the measurement of bone mineral density (BMD) or bone mineral content (BMC) in the spine. Thirty patients on PD had DXA scans of the lumbar spine and hip completed before and after the drainage of peritoneal dialysate. A paired t-test was used to compare the difference in area, BMC, and BMD before and after drainage of dialysate. A significant difference was found in the BMC of the spine before and after the drainage of dialyzate. We recommend that peritoneal dialyzate be removed prior to scanning patients on PD and that densitometry technologists should be observant about the presence of peritoneal dialysate.

Relationship between bone mineral density and biochemical markers of bone turnover in hemodialysis patients

End-stage renal disease is closely associated with changes in bone and mineral metabolism. In recent times, osteoporosis has become important among hemodialysis (HD) patients. In this study, the investigators sought to evaluate the relationship between bone mineral density (BMD) and biochemical markers of bone turnover among HD patients. A total of 70 uremic patients on a maintenance HD program for at least 1 y were enrolled in the study. All patients were treated with conventional bicarbonated HD for 5 h through the use of low-flux hollow-fiber dialyzers. Bone densitometry was measured by dual energy x-ray absorptiometry in the lumbar spine (LS) and the femoral neck (FN). BMD was classified according to World Health Organization criteria on the basis of BMD T scores. Biochemical bone turnover markers such as calcium, phosphorus, ionized calcium, intact parathyroid hormone, alkaline phosphatase, plasma bicarbonate, blood pH, serum albumin, and hematocrit levels were measured before the HD session in the morning. Male patients (n=37; 52.9%; mean age, 46.2+/-17.0 y) were assigned to a single study group, and female patients (n=33; 47.1%; mean age, 44.0+/-13.1 y) to another. Mean duration of HD treatment was 33.7+/-28.5 mo in females and 33.0+/-26.0 mo in males. Among all patients, BMD T scores in the osteopenia/osteoporosis range were observed at the LS in 58 patients (82.8%) and at the FN in 45 patients (64.3%). According to BMD measurements in FN T score, 10% of patients (n=7) were osteoporotic, 54.3% (n=38), osteopenic, and 35.7% (n=25), normal. On the other hand, in LS T score, the results were 47.1% (n=33) osteoporotic, 35.7% (n=25), osteopenic, and 17.1% (n=12), normal. No statistically significant association was found in osteopenia/osteoporosis between sexes according to FN and LS T score (P=.542, P=.267, respectively). No significant relationship was noted between BMD and biochemical markers of bone turnover. A positive correlation was found between FN T scores of BMD and age (r=.413, P=.000). BMD T scores within the range of scores for osteopenia/osteoporosis were observed in 78.5% of patients at the LS and in 58.5% of patients at the FN. The investigators concluded that no correlation could be found between markers of bone turnover and bone mass measurements in both skeletal regions. LS T score results were worse than FN T score results. Elevated alkaline phosphastase levels combined with high intact parathyroid hormone levels are predictive of renal osteodystrophy but not of adynamic bone disease/osteoporosis.