On the evolving nature of understanding dialysis-related disorders

Prognostic Value of the Malnutrition-inflammation Score in Hospitalization and Mortality on Long-term Hemodialysis

OBJECTIVE

Since its development, cumulative evidence has accumulated regarding the prognostic value of the Malnutrition-Inflammation Score (MIS/Kalantar score) prognostic value; however, there is a shortage of recent and large studies with comprehensive statistical methodologies that contribute to support a higher level of evidence and a consensual cutoff. The aim of this study was to assess the strength of MIS association with hospitalization and mortality in a nationwide cohort.

METHODS

This was a historical cohort study of hemodialysis patients from 25 outpatient centers followed up for 48 months. Univariable and multivariable Cox additive regression models were used to analyze the data. The C-index was estimated to assess the performance of the final model.

RESULTS

Two thousand four hundred forty-four patients were analyzed, 59.0% males, 32.0% diabetic, and median age of 71 years (P₂₅ = 60, P₇₅ = 79). During a median period of 45-month follow-up, with a maximum of 48 months (P₂₅ = 31; P₇₅ = 48), 875 patients presented an MIS <5 (35.8%) and 860 patients (35.2%) died. The proportion of deaths was 23.1% for patients with the MIS <5 and 41.9% if the MIS ≥5 (P < .001). A total of 1,528 patients (62.5%) were hospitalized with a median time to the first hospitalization of 26 months (P₂₅ = 9; P₇₅ = 45). A new cutoff point regarding the risk of death, MIS ≥6, was identified for this study data set. In multivariable analysis for hospitalization risk, a higher MIS, higher comorbidity index, and arteriovenous graft or catheter increased the risk, whereas higher Kt/V and higher albumin had a protective effect. In multivariable analysis for mortality risk, adjusting for age, albumin, normalized protein catabolic rate, Charlson comorbidity index, interdialytic weight gain, Kt/V, diabetes, hematocrit, and vascular access, patients with the MIS ≥6 showed a hazard ratio of 1.469 (95% confidence interval: 1.262-1.711; P < .001). Higher age, higher interdialytic weight gain, higher comorbidity index, and catheter increased significantly the risk, whereas higher Kt/V, higher albumin, and higher normalized protein catabolic rate (≥1.05 g/kg/d) reduced the risk.

CONCLUSION

The MIS maintains its relevant and significant association with hospitalization and mortality.

Association between Serum Dickkopf-1 (DKK-1) Glycoprotein and Calcific Deposits on Cardiac Valves and Carotid Intimal-Medial Thickness in Hemodialysis Patients

BACKGROUND

Cardiac valve calcification (CVC) is common in hemodialysis (HD) patients, and associated with cardiovascular and all-cause mortality. Once believed to be a passive process, it is now understood that the Wnt signaling pathway has a major role. The aim of the current study was to assess the relationship between circulating DKK-1, a negative regulator of the Wnt signaling pathway, and CVC, as well as carotid intimal-medial thickness (CIMT) in HD patients.

METHODS

We enrolled 74 consecutive adults on maintenance HD. Echocardiographic calcification of the mitral valve (MV) and aortic valve (AV) were detected according to Wilkins score (range 0-4), and the study of Tenenbaum et al. [Int J Cardiol. 2004 Mar;94(1):7-13] (range 0-4), respectively. CVC severity was calculated by a supposed score (range 0-8) that represents the sum of calcification grade of MV and AV. CVC severity was classified into absent (CVC score = 0), mild (CVC score = 1-2), moderate (CVC score = 3-4), and severe (CVC score ≥5). Demographic and biochemical data were collected in addition to serum DKK-1 levels and CIMT.

RESULTS

CVC was present in 67 patients (91.0%). There was a highly significant negative correlation between serum DKK-1 level and CVC score (r = -0.492; p ≤ 0.001), as well as CIMT (r = -0.611; p ≤ 0.001). Age and CIMT were independent determinants of CVC.

CONCLUSIONS

CVC is almost present in all HD patients. DKK-1 seems to have a direct relation with CVC and CIMT in HD patients. Age is the strongest independent determinant of CVC.

Calcium balance in hemodialysis: More uncertainty than certainty

There is controversy about the choice of dialysate calcium concentration (DCa), with strong arguments both in favor of and against the use of a low or high DCa, as they can both be potentially harmful. Evidence suggests that calcium mass balance is positive with a DCa 3.5 mEq/L, negative or neutral with the use of DCa 2.5 mEq/L, whereas both positive and negative balances have been observed with the use of DCa 3.0 mEq/L. Overall, the use of DCa >2.5 mEq/L is usually associated with an increase in serum calcium level and a decrease in serum PTH level and use of lower vitamin D analogue dose, with the opposite effects usually observed with the use of lower DCa. Most of the available evidence is from small-sized and crossover studies; hence, evidence should be regarded with caution and applied in a patient-specific manner. As there are a lot of significant unanswered questions regarding calcium balance and the optimal DCa in hemodialysis patients, further high-quality research is needed to clarify many still unclear aspects of calcium homeostasis and balance in these patients. In conclusion, with the existing evidence the choice of DCa needs to be individualized and contextualized in the setting of each patient's calcium balance needs and homeostatic response, taking also into account oral calcium intake (dietary and medicinal), any other relevant therapy administered, such as vitamin D analogues, the type of renal mineral bone disorder, and associated cardiovascular comorbidity.

Registered dietitian nutritionists and perceptions of liberalizing the hemodialysis diet

BACKGROUND/OBJECTIVES

The objective of this study was to assess the level of awareness, comfort, and likelihood of liberalizing the hemodialysis diet in practicing renal registered dietitian nutritionists (RDN).

SUBJECTS/METHODS

An original, cross-sectional survey was sent to the Academy of Nutrition and Dietetics' Renal Practice Group in May 2017, consisting primarily of renal dietitians.

RESULTS

A total of 187 renal dietitians responded to the survey designed to assess their current practices regarding the renal diet for hemodialysis patients and how comfortable they would be liberalizing the current restrictions. On average, 16.3% of dietitians are extremely likely to liberalize the restrictions on various food groups including fruits and vegetables, beans and legumes, and whole grains.

CONCLUSIONS

RDN feel confident in their ability to interpret and apply evidence-based literature into practice, and they are moderately comfortable liberalizing the renal diet. The participants were generally more comfortable liberalizing the phosphorus restriction than the potassium restriction, and the sodium restriction remains important to control interdialytic weight gain and hypertension. Future research is needed to establish efficacy of a liberalized diet as well as interventions to help RDN feel more comfortable implementing a liberalization of the renal diet.

Chronic Kidney Disease Worsens Health Outcomes in Diabetic Patients After Hip Fracture Surgery: An Asian Nationwide Population-Based Cohort Study

There is an increased tendency for hip fractures in patients with chronic kidney disease (CKD). Although surgery is the mainstay of treatment for hip fractures, there is scant information on outcomes after hip fracture surgery in diabetic patients at different stages of CKD. In this population-based cohort study, we compared the surgical outcome, readmission, and mortality rates after osteosynthesis of hip fractures in diabetic patients with different stages of renal function. Diabetic patients who received primary osteosynthesis for hip fracture between January 1997 and December 2013 were enrolled. The primary outcomes were surgical outcomes, including infection and revision surgery. The secondary outcomes were all-cause readmission and mortality. This study included 44,065 patients; 11,954 had CKD (diabetic CKD group), 1662 patients were receiving dialysis (diabetic dialysis group), and 30,449 patients had no CKD (diabetic non-CKD group). We found that the diabetic dialysis group had a significantly higher risk of infection and revision surgery compared with diabetic non-CKD patients (HR = 1.52, 95% CI, 1.24 to 1.87; HR = 1.62, 95% CI, 1.33 to 1.97, respectively, both P < 0.001) and diabetic CKD patients (HR = 1.62, 95% CI, 1.32 to 1.99; HR = 1.48, 95% CI, 1.22 to 1.80, respectively, both P < 0.001). Diabetic CKD patients had a comparable risk of surgical complications including infection and revision as diabetic non-CKD patients. For readmission and mortality, the diabetic dialysis group had the highest risk among the three groups at all time-points (3 months after surgery, 1 year, and the last follow-up, all P < 0.001). Compared with the diabetic non-CKD group, the diabetic CKD group had an elevated risk of readmission and mortality at all time-points (all P < 0.001). In conclusion, CKD was associated with worse outcomes after hip fracture fixation surgery. Although at significantly higher risk of readmission and mortality, CKD patients still had a comparable risk of infection and revision to non-CKD patients. © 2019 American Society for Bone and Mineral Research.

Sudden onset of parathyroid hormone-independent severe hypercalcemia from reversal of tumoral calcinosis in a dialysis patient

Background

Tumoral calcinosis is a rare manifestation of extraskeletal calcification, featuring large calcified cystic masses in the periarticular regions of large joints. In chronic kidney disease (CKD), this disorder is thought to evolve through a chronically elevated calcium-phosphorus solubility product leading to calcium precipitation in soft tissue. Treating tumoral calcinosis in these patients involves interventions to lower the calcium-phosphorus product such as reduction in vitamin D therapy and intensive hemodialysis regimens.

Case Presentation

We report the case of a 54-year old woman with polycystic kidney disease on peritoneal dialysis with widespread tumoral calcinosis in the context of hypercalcemic tertiary hyperparathyroidism who had been on long-term alfacalcidol therapy. After withdrawal of the vitamin D analogue and initiation of daily hemodialysis, there was rapid dissolution of her tumoral calcium deposits with the abrupt onset of parathyroid hormone (PTH)-independent transient hypercalcemia that resolved once the soft tissue deposits disappeared.

Conclusions

Resorption of soft tissue calcific deposits may result in transient parathyroid hormone (PTH)-independent hypercalcemia. In CKD patients, this hypercalcemia causes a decrease in the PTH level, distinguishing it from tertiary hyperparathyroidism, though PTH may not be totally suppressed, the way it is seen in PTH-independent hypercalcemia in non-CKD patients.

Optimal care of lupus nephritis patients

Optimal care of lupus nephritis patients should include the treatment of proteinuria and hypertension, other measures to delay the progression of chronic kidney disease, the vigorous management of cardiovascular risk factors and finally, the treatment of advanced chronic kidney disease and its consequences. These topics are briefly reviewed in the present paper, with particular emphasis on the recent progresses in antiproteinuric treatment.

Preclinical studies of VS-505: a non-absorbable highly effective phosphate binder

BACKGROUND AND PURPOSE

Phosphate imbalance is often present in chronic kidney disease (CKD), and it contributes to a higher cardiovascular mortality rate. A phosphate binder is typically part of a treatment strategy for controlling phosphate imbalance. However, safety concerns and low compliance are two well-recognized disadvantages of on-market phosphate binders. This report describes the preclinical studies of VS-505, a non-absorbable, calcium- and aluminum-free, plant-derived polymer currently being evaluated in haemodialysis patients in Australia.

EXPERIMENTAL APPROACH

Normal Sprague Dawley (SD) rats or uraemic SD rats induced by 5/6 nephrectomy fed a high-phosphate diet were treated with VS-505 or sevelamer (0.05-10% in food) for 5 and 28 days respectively.

KEY RESULTS

Urinary and serum phosphate levels were significantly elevated in untreated rats, and were decreased by VS-505 and sevelamer. VS-505 increased faecal phosphate levels in a dose-dependent manner. High-phosphate diet also caused an increase in serum FGF-23 and parathyroid hormone in nephrectomized (NX) rats, effects prevented by VS-505 or sevelamer. Significant aortic calcification was observed in NX rats treated with 5% sevelamer, whereas VS-505 at all doses tested did not show effects. VS-505 had no effects on small intestine histomorphology and intestinal sodium-dependent phosphate cotransporter gene expression. In vitro characterizations showed that VS-505 has a relatively high density and low expansion volume when exposed to simulated gastric fluid.

CONCLUSIONS AND IMPLICATIONS

VS-505 is a safe and effective phosphate binder and may offer the advantage of having a reduced pill burden and minimal GI side effects for CKD patients.

Modifications to bicarbonate conductivity: A way to increase phosphate removal during hemodialysis? Proof of concept

Introduction Hyperphosphatemia and cardiovascular mortality are associated particularly with end-stage renal disease. Available therapeutic strategies (i.e., diet restriction, calcium [or not]-based phosphate binders, calcimimetics) are associated with extrarenal blood purification. Compartmentalization of phosphate limits its depuration during hemodialysis. Several studies suggest that plasmatic pH is involved in the mobilization of phosphate from intracellular to extracellular compartments. Consequently, the efficiency of modified bicarbonate conductivity to purify blood phosphate was tested. Methods Ten hemodialysis patients with chronic hyperphosphatemia (>2.1 mmol/L) were included in the two three-sessions-per week periods. Bicarbonate concentration was fixed at 40 mmol/L and 30 mmol/L in the first and second periods, respectively. Phosphate depuration was evaluated by phosphate mobilization clearance (K_M ). Findings Although bicarbonatemia was lower during the second period (21.0 ± 2.7 vs. 24.4 ± 3.1 mmol/L, P < 0.01), no difference was observed in phosphatemia (2.4 ± 0.5 vs. 2.3 ± 0.4 mmol/L, P = NS). The in-session variation of phosphate was lower (-1.45 ± 0.42 vs. -1.58 ± 0.44 mmol/L, P < 0.05) and K_M was higher during the second period (82.94 ± 38.00 vs. 69.74 ± 24.48 mL/min, P < 0.05). Discussion The decrease of in-session phosphate and the increase in K_M reflect phosphate refilling during hemodialysis. Thus, modulation of serum bicarbonate may play a role in controlling the phosphate pool. Even though correcting metabolic acidosis during hemodialysis remains important, alkaline excess can impair phosphate mobilization clearance. Clinical trials are needed to test the efficiency and relevance of a strategy where bicarbonatemia is corrected less at the beginning of sessions.

Cinacalcet versus standard treatment for chronic kidney disease: a protocol for a systematic review and meta-analysis

BACKGROUND

Chronic kidney disease-mineral and bone disorders (CKD-MBD) have been associated with poor health outcomes, including diminished quality and length of life. Standard management for CKD-MBD includes phosphate-restricted diet, active vitamin D, vitamin D analogs, and phosphate binders. Persistently elevated parathyroid hormone (PTH) levels may require the addition of Cinacalcet hydrochloride (cinacalcet) which sensitizes calcium receptors on the parathyroid glands. The objective of this systematic review is to compare the effect of cinacalcet versus standard treatment in patients with CKD-MBD.

METHODS/DESIGN

Data sources will include MEDLINE, EMBASE, the Cochrane Register of Controlled Trials, and Web of Science from 1996 to June 2015. Teams of two reviewers will, independently and in duplicate, screen titles and abstracts and potentially eligible full text reports to determine eligibility, and subsequently abstract data and assess risk of bias in eligible trials. We will calculate the effect estimates (risk ratios or mean differences) and 95 % confidence intervals, as well as statistical measures of variability in results across studies using random effect models for patient-important and intermediate outcomes. We will use the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach to rate the quality of evidence about estimates of effect on an outcome-by-outcome basis. We will present our results with a GRADE summary table.

DISCUSSION

Our review will explore the effect of cinacalcet versus standard treatment in patients with CKD-MBD. The results of this systematic review will help guide management of this patient population, and identify targets for future research.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015020318 http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42015020318.

Parathyroidectomy is underused in patients with tertiary hyperparathyroidism after renal transplantation

BACKGROUND

Parathyroidectomy (PTX) is the only curative treatment for tertiary hyperparathyroidism (3HPT). With the introduction of calcimimetics (cinacalcet), PTX can sometimes be delayed or avoided. The purpose of this study was to determine the current incidence of utilization of PTX in patients with posttransplant 3HPT with the advent of cinacalcet.

METHODS

We evaluated renal transplant patients between January 1, 2004, and June 30, 2012, with a minimum of 24 months follow-up who had persistent allograft function. Patients with an increased serum level of parathyroid hormone (PTH) at 1 year after successful renal transplantation with normocalcemia or hypercalcemia were defined as having 3HPT. A multivariate logistic regression model was constructed to determine factors associated with undergoing PTX.

RESULTS

We identified 618 patients with 3HPT, only 41 (6.6%) of whom underwent PTX. Patients with higher levels of serum calcium (P < .001) and PTH (P = .002) posttransplant were more likely to be referred for PTX. Importantly, those who underwent PTX had serum calcium and PTH values distributed more closely to the normal range on most recent follow-up. PTX was not associated with rejection (P = .400) or with worsened allograft function (P = .163).

CONCLUSION

PTX seems to be underused in patients with 3HPT at our institution. PTX is associated with high cure rates, improved serum calcium and PTH levels, and is not associated with rejection.

AN OVERVIEW OF NURSES' MANAGEMENT OF SECONDARY HYPERPARATHYROIDISM: HOW IS EUROPE DOING?

BACKGROUND

Nurses have an important role to play in the management of secondary hyperparathyroidism (SHPT). An online survey conducted by the European Dialysis and Transplant Nurses Association/European Renal Care Association (EDTNA/ERCA) in conjunction with Amgen (Europe) GmbH surveyed nephrology nurses' knowledge of secondary hyperparathyroidism, treatment targets, current treatments, patient adherence and nephrology nurse training education needs. The survey's aim was to establish common practices being used by nurses in the management of secondary hyperparathyroidism and to identify nephrology nurses' training and educational needs in order to improve patient care.

METHODS

DESIGN

Descriptive study.

MEASUREMENTS

An online survey of multiple choice and closed questions.

PARTICIPANTS

A sample of nephrology nurses from Spain, Italy, France and the Netherlands.

RESULTS

A total of 111 nurses completed the questionnaire (98% response rate, 82% of which were fully completed). Collected data revealed that there were specific aspects of SHPT patient management where nurses lacked confidence, despite the majority of respondents having 15 years nephrology nursing experience. These aspects included explaining the disorder and therapies to patients, managing side effects of drugs and appreciating the significance of controlling biochemical targets. Over 40% of the respondents felt they did not have sufficient training to support patients who were non-compliant.

CONCLUSION

Nursing skills are integral to SHPT patient management as part of the multidisciplinary approach. The nurse's role is particularly important in patient assessment and monitoring, and in the provision of patient education and support, particularly with treatment adherence. Nephrology nurses who are better informed about SHPT and who receive training on practical patient care may improve the care of patients.

Aluminum transfer during dialysis: a systematic review

PURPOSE

Dialysis-dependent patients are particularly susceptible to the toxic effects of aluminum (Al) because of their impaired ability to eliminate it. Al contamination of dialysis fluid remains a threat in this population. The mechanism for Al diffusion across dialysis membranes is not well established. Our objective is to verify, in AL-exposed patients, the postulate that the direction of Al transfer is predicted by the concentration gradient between free diffusible plasma Al and dialysate Al.

METHODS

A systematic review of the literature was performed. Only papers which included Al plasma concentration ([Al]p), Al dialysate concentration ([Al]d) and direction of Al transfer (positive = from dialysate to plasma, negative = from plasma to dialysate) were selected. We also included four patients from our own cohort. Assuming that [Al]p has an ultrafiltrable fraction between 17 and 23%, cases were considered in keeping with our hypothesis if any of the following scenarios was present: negative Al transfer when [Al]d < [Al]p*23% and positive Al transfer when [Al]d > [Al]p*17%.

RESULTS

The search yielded 409 articles, of which 12 were selected for review. When reviewing individual patients for analysis, 108 out of 115 (94%) patients followed our hypothesis. By further excluding cases in which Al transfer could not be determined, only three out of 111 patients were contrary to out hypothesis.

CONCLUSION

Comparing ultrafiltrable Al to dialysate Al permits to accurately predict the direction of Al transfer. The optimal [Al]d should be <20% of the maximally acceptable [Al]p. In order to follow K/DOQI guidelines ([Al]p < 20 μg/L), the [Al]d should therefore not exceed 4 μg/L. At the level presently supported by K/DOQI ([Al]d < 10 μg/L), [Al]p could realistically reach 50 μg/L and potentially cause toxicity.

The effects of colestilan versus placebo and sevelamer in patients with CKD 5D and hyperphosphataemia: a 1-year prospective randomized study

BACKGROUND

This study compared the effects of short-term titrated colestilan (a novel non-absorbable, non-calcium, phosphate binder) with placebo, and evaluated the safety and efficacy of colestilan over 1 year compared with sevelamer, in patients with chronic kidney disease (CKD) 5D.

METHODS

This prospective multicentre study comprised a 4-week phosphate binder washout period, a 16-week short-term, flexible-dose, treatment period (including a 4-week placebo-controlled withdrawal period) and a 40-week extension treatment phase.

RESULTS

At Week 16 (the end of the 4-week placebo-controlled withdrawal period), serum phosphorus level was 0.43 mmol/L (1.32 mg/dL) lower with colestilan than placebo (P < 0.001; primary end point). Serum LDL-C level was also lower with colestilan than with placebo (P < 0.001). Both colestilan and sevelamer produced significant reductions from baseline in serum phosphorus levels (P < 0.001), maintained for 1 year, and the proportion of patients achieving target levels of ≤1.78 mmol/L (5.5 mg/dL) or ≤1.95 mmol/L (6.0 mg/dL) at study end were similar (65.3 and 73.3%, respectively, for colestilan, and 66.9 and 77.4%, respectively, for sevelamer). Serum calcium level remained stable in the colestilan group but tended to increase slightly in the sevelamer group (end-of-study increase of 0.035 mmol/L over baseline). Both binders produced similar reductions from baseline in LDL-C level (P < 0.001), and responder rates after 1 year, using a target of <1.83 mmol/L (70 mg/dL) or <2.59 mmol/L (100 mg/dL) were similar in both groups (50.7 and 85.3% for colestilan and 54.0 and 80.6% for sevelamer). Colestilan was generally well tolerated.

CONCLUSIONS

Colestilan is effective and safe for the treatment of hyperphosphataemia in patients with CKD 5D, and affords similar long-term phosphorus and cholesterol reductions/responder rates to sevelamer.

Lanthanum carbonate versus placebo for management of hyperphosphatemia in patients undergoing peritoneal dialysis: a subgroup analysis of a phase 2 randomized controlled study of dialysis patients

BACKGROUND

This short-term study assessed the efficacy and safety of lanthanum carbonate in the treatment of hyperphosphatemia in dialysis patients; here, we report a prespecified subgroup analysis of patients undergoing peritoneal dialysis.

METHODS

Men and women (n=39) who had received continuous ambulatory peritoneal dialysis for chronic kidney disease for 6 months or more were enrolled in eight renal medicine departments in the United Kingdom. A 2-week washout period was followed by a 4-week dose-titration phase during which patients received lanthanum carbonate titrated up to 2250 mg/day. This was followed by a 4-week, randomized, placebo-controlled, parallel-group phase during which patients continued to receive either lanthanum carbonate at the titrated dose, or a matched dose of placebo. The main outcome measure was control of serum phosphate levels (1.3-1.8 mmol/l) at the end of the parallel-group phase.

RESULTS

Serum phosphate was controlled in 3/39 (8%) patients at the beginning of the dose-titration phase (after washout) and in 18/31 (58%) patients treated with lanthanum carbonate at its end. After the parallel-group phase, 60% of lanthanum carbonate-treated patients and 10% of those receiving placebo had controlled serum phosphate. There was no difference in mean (95% confidence interval) serum phosphate levels between groups at randomization: lanthanum carbonate, 1.57 (1.34-1.81) mmol/l; placebo, 1.58 (1.40-1.76) mmol/l (p=0.96). However, a difference was seen at the end of the parallel-group phase: lanthanum carbonate, 1.56 (1.33-1.79) mmol/l; placebo, 2.25 (1.81-2.68) mmol/l (p=0.0015). There were no clinically important changes in nutritional parameters and no serious treatment-related adverse events were recorded.

CONCLUSIONS

At doses up to 2250 mg/day, lanthanum carbonate is well tolerated and controls hyperphosphatemia effectively. Treatment with higher doses of lanthanum carbonate may allow patients undergoing peritoneal dialysis the potential to increase their dietary protein intake without compromising their phosphate control.

Growth retardation in children with kidney disease

Growth failure is almost inextricably linked with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Growth failure in CKD has been associated with both increased morbidity and mortality. Growth failure in the setting of kidney disease is multifactorial and is related to poor nutritional status as well as comorbidities, such as anemia, bone and mineral disorders, and alterations in hormonal responses, as well as to aspects of treatment such as steroid exposure. This review covers updated management of growth failure in these children including adequate nutrition, treatment of metabolic alterations, and early administration of recombinant human growth hormone (GH).

Risk factors for peripheral arterial disease among patients with chronic kidney disease

Patients with chronic kidney disease (CKD) have an increased risk for developing peripheral arterial disease (PAD). The aim of this study was to examine the cross-sectional association between novel risk factors and prevalent PAD in patients with CKD. A total of 3,758 patients with estimated glomerular filtration rates of 20 to 70 ml/min/1.73 m(2) who participated in the Chronic Renal Insufficiency Cohort (CRIC) study were included in the present analysis. PAD was defined as an ankle-brachial index <0.9 or a history of arm or leg revascularization. After adjustment for age, gender, race, cigarette smoking, physical activity, history of hypertension and diabetes, pulse pressure, high-density lipoprotein cholesterol, estimated glomerular filtration rate, and CRIC clinical sites, several novel risk factors were significantly associated with PAD. For example, odds ratios for a 1-SD higher level of risk factors were 1.18 (95% confidence interval [CI] 1.08 to 1.29) for log-transformed high-sensitivity C-reactive protein, 1.18 (95% CI 1.08 to 1.29) for white blood cell count, 1.15 (95% CI 1.05 to 1.25) for fibrinogen, 1.13 (95% CI 1.03 to 1.24) for uric acid, 1.14 (95% CI 1.02 to 1.26) for glycosylated hemoglobin, 1.11 (95% CI 1.00 to 1.23) for log-transformed homeostasis model assessment of insulin resistance, and 1.35 (95% CI 1.18 to 1.55) for cystatin C. In conclusion, these data indicate that inflammation, prothrombotic state, oxidative stress, insulin resistance, and cystatin C were associated with an increased prevalence of PAD in patients with CKD. Further studies are warranted to examine the causal effect of these risk factors on PAD in patients with CKD.

Initial parathyroid surgery in 606 patients with renal hyperparathyroidism

BACKGROUND

The aim of the present study was to evaluate the outcome of different surgical procedures for patients on permanent dialysis who underwent initial parathyroidectomy for renal hyperparathyroidism (rHPT).

METHODS

Out of a prospective database of patients who underwent parathyroid surgery for rHPT between 1976 and 2009, patients on permanent dialysis who underwent initial parathyroidectomy were further analyzed regarding perioperative biochemical changes and postoperative outcome.

RESULTS

A total of 606 patients were analyzed. Total parathyroidectomy with autotransplantation (group A) was performed in 504 patients, total parathyroidectomy without autotransplantation in 32 (group B), subtotal parathyroidectomy in 21 (group C), and incomplete parathyroidectomy in 49 (group D). After surgery, mean calcium levels dropped from 2.76 to 1.91 mmol/l in group A, from 2.67 to 2.11 mmol/l in group B, from 2.70 to 2.09 mmol/l in group C, and from 2.65 to 1.94 mmol/l in group D. The parathyroid hormone level dropped from 1,371.4 pg/ml to 28.8 pg/ml in group A, from 1,078.4 pg/ml to 27.0 pg/ml in group B, from 2,377.9 pg/ml to 61.4 pg/ml in group C, and from 1,010.2 pg/ml to 99.5 pg/ml in group D. Persistent rHPT occurred in 2/504 patients from group A (0.4%), 0/32 patients from group B (0%), 1/21 patients from group C (4.8%), and 2/49 patients from group D (4.1%). After a mean follow-up of 57.6 months, recurrent rHPT occurred in 27/504 patients from group A (5.4%), in 0/32 patients from group B (0%), in 2/21 patients from group C (9.5%), and in 3/49 patients from group D (6.1%).

CONCLUSIONS

Total parathyroidectomy with or without autotransplantation is a feasible and safe surgical procedure for patients on permanent dialysis with otherwise uncontrollable rHPT.

Cinacalcet hydrochloride therapy for secondary hyperparathyroidism in hemodialysis patients

This study compared the efficacy of a cinacalcet-based regimen with unrestricted conventional therapy (vitamin D and phosphate binders) for achieving Kidney Disease Outcome Quality Initiative (K/DOQI) targets for dialysis patients. In this multicenter, prospective study, hemodialysis patients with poorly controlled secondary hyperparathyroidism (SHPT) were randomized to receive a cinacalcet-based regimen (n=55) or a conventional therapy (n=27). Doses of cinacalcet, vitamin D sterols, and phosphate binders were adjusted during a 12-week dose-titration phase to achieve intact parathyroid hormone (iPTH) levels ≤ 31.8 pmol/L. The primary end point was the percentage of patients with values in this range during a 24-week efficacy-assessment phase. The clinical response to 36-week cinacalcet treatment was evaluated. A dual energy X-ray absorptiometry was performed before and after 36 weeks of cinacalcet therapy. Fifty-eight percent of the cinacalcet group reached the primary end point, as compared with 19% of the conventional therapy group (P=0.001). A higher percentage of patients receiving the cinacalcet-based regimen versus conventional therapy achieved the targets for calcium, phosphorus and Ca×P. Achievement of targets was greatest in patients with less severe disease (intact PTH range, 31.8 to 53 pmol/L). Cinacalcet therapy increased proximal femur bone mineral density (BMD), but did not affect the lumbar spine. Itching intensity decreased significantly. Cinacalcet based treatment facilitates achievement of the K/DOQI targets for iPTH and bone mineral metabolism compared with conventional therapy in hemodialysis patients. Suppression of iPTH with cinacalcet reverses bone loss in the proximal femur. Cinacalcet alleviated itching.

Role of the renin-angiotensin system in the pathogenesis of intimal hyperplasia: therapeutic potential for prevention of vein graft failure?

The saphenous vein remains the most widely used conduit for peripheral and coronary revascularization despite a high rate of vein graft failure. The most common cause of vein graft failure is intimal hyperplasia. No agents have been proven to be successful for the prevention of intimal hyperplasia in human subjects. The renin-angiotensin system is essential in the regulation of vascular tone and blood pressure in physiologic conditions. However, this system mediates cardiovascular remodeling in pathophysiologic states. Angiotensin II is becoming increasingly recognized as a potential mediator of intimal hyperplasia. Drugs modulating the renin-angiotensin system include angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. These drugs are powerful inhibitors of atherosclerosis and cardiovascular remodeling, and they are first-line agents for management of several medical conditions based on class I evidence that they delay progression of cardiovascular disease and improve survival. Several experimental models have demonstrated that these agents are capable of inhibiting intimal hyperplasia. However, there are no data supporting their role in prevention of intimal hyperplasia in patients with vein grafts. This review summarizes the physiology of the renin-angiotensin system, the role of angiotensin II in the pathogenesis of cardiovascular remodeling, the medical indications for these agents, and the experimental data supporting an important role of the renin-angiotensin system in the pathogenesis of intimal hyperplasia.

Cost-effectiveness of lanthanum carbonate versus sevelamer hydrochloride for the treatment of hyperphosphatemia in patients with end-stage renal disease: a US payer perspective

OBJECTIVE

To assess the cost-effectiveness of lanthanum carbonate (LC) versus sevelamer hydrochloride (SH) as a treatment for hyperphosphatemia in end-stage renal disease (ESRD) patients.

METHODS

A Markov model was developed to estimate health outcomes; quality-adjusted life years (QALYs) and life-years saved (LYS), as well as associated costs. The model incorporated patient-level data from a randomized head-to-head crossover study that compared the reduction of serum phosphorus using LC and SH for 4 weeks each. The model included patients previously treated with calcium-based binders. Both the intent-to-treat (ITT) population and the cohort of patients who completed treatment in both periods of the study (i.e., completer population) were assessed. The baseline risks of cardiovascular disease (CVD), all-cause mortalities for CVD, and non-CVD patients were derived from a large US renal database. Patient outcomes were modeled for 10 years, and incremental cost-effectiveness ratios (ICERs) were calculated for LC relative to SH. Deterministic and probabilistic sensitivity analyses (PSA) were performed to test the robustness of the base-case model.

RESULTS

For the ITT population, the ICERs of LC versus SH were $24,724/QALY and $15,053/LYS, respectively (in US dollars). When the completer population was considered, the ICERs of LC versus SH were $15,285/QALY and $9,337/LYS (Table 2), respectively. The PSA indicated 61.9% and 85.8% probabilities for ITT and completer populations of LC being cost-effective at the $50,000/QALY willingness-to-pay threshold, respectively.

CONCLUSION

LC is a cost-effective strategy compared with SH in the treatment of ESRD patients with hyperphosphatemia who were previously treated with calcium-based binders. Sensitivity analyses demonstrated the robustness of the pharmacoeconomic model.

Vitamin d and stage 5 chronic kidney disease: a new paradigm?

Vitamin D receptor agonists (VDRA) are currently recommended for the treatment of secondary hyperparathyroidism in stage 5 CKD. They are considered to be contraindicated in the presence of low or normal (for a dialysis patient) levels of PTH due to the risk of developing adynamic bone disease, with consequent vascular calcification. However, these recommendations are increasingly at odds with the epidemiological evidence, which consistently shows a large survival advantage for patients treated with low-dose VDRAs, regardless of plasma calcium, phosphate, or PTH. A large number of pleiotropic effects of vitamin D have been described, including inhibition of renin activity, anti-inflammation, and suppression of vascular calcification stimulators and stimulation of vascular calcification inhibitors present in the uremic milieu. Laboratory studies suggest that a normal cellular vitamin D level is necessary for normal cardiomyocyte and vascular smooth muscle function. While pharmacological doses of VDRA can be harmful, the present evidence suggests that the level of 1,25-dihydroxycholecalciferol should also be more physiological in stage 5 CKD, and that widespread use of low-dose VDRA would be beneficial. A randomized controlled trial to test this hypothesis is warranted.

[Surgical treatment of secondary hyperparathyroidism in patients with chronic renal failure]

OBJECTIVE

To identify the indications for subtotal parathyroidectomy (PTX) in secondary hyperparathyroidism (SHPT) and report postoperative, early and late complications of PTX.

PATIENTS AND METHODS

We conducted a retrospective study of subjects with chronic renal failure operated in Tunisian hospitals who received subtotal PTX over 10 years from January 1997 to December 2007. We analyzed the clinical, biological and radiological parameters pre- and postoperatively.

RESULTS

We included 70 patients with average age of 39.4 years, 55.7% men and 44.3% in dialysis for 7.75 ± 4.8 years before PTX. The initial nephropathy was interstitial in 50% of cases. No cases of diabetic nephropathy have been reported. The clinical signs were bone pain (88.6%), muscle pain (85.6%), pruritus (81.4%). Radiological signs of osteitis fibrosa were observed in the majority of patients mainly resorption of extremities (92.9%), thinning of cortical (85.7%) and osteosclerosis (87.1%). The most common indication of PTX (85.7% of cases) was the persistence of serum PTH of more than 800 pg/ml associated with hypercalcemia and/or hyperphosphatemia refractory to medical treatment. A subtotal PTX (3/4 or 7/8) was performed after ultrasound and scintigraphy in the majority of cases. The histology of the parathyroid glands showed diffuse hyperplasia (51.4%), nodular hyperplasia (45.7%) and adenoma (2.8%). The postoperative evolution was marked by an improvement of the clinical and radiological criteria in 80% of cases. A PTH level of less than 15 pg/ml was rarely observed (10% of cases), and a PTH level of more than 300 pg/ml concerned 13% of patients. We noted a low morbidity and mortality (no cases laryngeal paralysis or cervical hematoma).

CONCLUSION

Surgical treatment of SHPT in Tunisia is very effective in our experience. The biological results are comparable to treatment with calcimimetics, not available in Tunisia and whose price is higher. An early treatment of disorders of bone and mineral metabolism should reduce the incidence of SHPT.

An assessment of cholesterol goal attainment in patients with chronic kidney disease

BACKGROUND

Patients with chronic kidney disease (CKD) are at significant risk for cardiovascular disease (CVD). The National Kidney Foundation developed clinical practice guidelines (Kidney Disease Outcomes Quality Initiative) for targeting low-density lipoprotein cholesterol (LDL-C) goals.

OBJECTIVE

This study evaluated the extent to which these guidelines were adhered to among patients with CKD and to examine factors associated with the attainment of LDL-C goals.

METHODS

In this cross-sectional study we evaluated patients with a glomerular filtration rate of 15 to 59 mL/min per 1.73 m². Patients with previous CVD, who were receiving dialysis, or were post kidney transplant were excluded. Administrative databases were used to determine the percentage of patients with a fasting lipid profile performed within the previous year, the percentage who attained a LDL-C goal less than 100 mg/dL, and to determine lipid-lowering medications prescribed. Logistic regression analysis was used to identify factors associated with LDL-C goal attainment.

RESULTS

Of the 4541 patients evaluated, 3157 (69.5%) had a fasting lipid profile performed within the previous year. Overall, 60.8% attained a LDL-C less than 100 mg/dL. Among patients at goal, 72.2% were taking lipid-lowering therapy compared with 37.9% of those not at goal (P < .01). Characteristics independently associated with LDL-C goal attainment were increasing age, male gender, increasing chronic disease score, history of diabetes, and statin use.

CONCLUSION

Although most patients were screened and attained LDL-C goal, there was room for improvement. Statin use was independently associated with LDL-C goal attainment. Future prospective studies should focus on evaluating clinical outcomes of lipid-lowering interventions within the CKD population.

Incidence, predictors and associated outcomes of rhabdomyolysis after kidney transplantation

BACKGROUND

There are several case reports of rhabdomyolysis (RM) in renal transplant recipients, but the actual incidence of this complication is not known. Most of the reported cases have been attributed to drug-drug interactions with calcineurin inhibitors, with the majority of interactions reported between cyclosporine and 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins). Pharmacokinetic studies have demonstrated that cyclosporine increases statin drug levels, presumably via competitive inhibition of cytochrome P450 3A4.

METHODS

In a retrospective cohort of 20 366 adult Medicare primary renal transplant recipients in the USRDS database transplanted from 1 January 2003 to 31 July 2005 and followed through 31 December 2005, we assessed Medicare claims for RM and dyslipidaemia (HPL), which was used as a surrogate for statin use.

RESULTS

The incidence rate of RM post-transplant for the study period was 1.4 (95% CI 1.1-1.8) per 1000 person-years. By Cox regression analysis, cyclosporine (versus tacrolimus) use [AHR 2.36 (95% CI 1.23-4.35); P = 0.006] and black race [AHR 2.33 (95% CI 1.30-4.17); P = 0.005] were associated with RM. By Cox non-proportional hazards regression, RM was associated with graft loss (including death) [AHR 2.84 (95% CI 1.70-4.72); P < 0.001].

CONCLUSIONS

RM is a rare complication after renal transplantation and is significantly associated with allograft loss (including death). RM is significantly more likely to occur with cyclosporine (versus tacrolimus)-based immunosuppression and possibly in persons of black race. Increased surveillance for RM is warranted in these at-risk patients.

Adynamic bone in patients with chronic kidney disease

Adynamic bone in patients with chronic kidney disease (CKD) is a clinical concern because of its potential increased risk for fracture and cardiovascular disease (CVD). Prevalence rates for adynamic bone are reportedly increased, although the variance for its prevalence and incidence is large. Differences in its prevalence are largely attributed to classification and population differences, the latter of which constitutes divergent groups of elderly patients having diabetes and other comorbidities that are prone to low bone formation. Most patients have vitamin D deficiency and the active form, 1,25-dihydroxyvitamin D, invariably decreases to very low levels during CKD progression. Fortunately, therapy with vitamin D receptor activators (VDRAs) appears to be useful in preventing bone loss, in part, by its effect to stimulate bone formation and in decreasing CVD morbidity, and should be considered as essential therapy regardless of bone turnover status. Future studies will depend on assessing cardiovascular outcomes to determine whether the risk/reward profile for complications related to VDRA and CKD is tolerable.

K/DOQI guideline requirements for calcium, phosphate, calcium phosphate product, and parathyroid hormone control in dialysis patients: can we achieve them?

BACKGROUND

Mineral metabolism has emerged as an important predictor of morbidity and mortality in dialysis patients. Kidney Disease Outcomes Quality Initiative (K/DOQI) clinical practice guidelines for bone metabolism and disease in chronic kidney disease (CKD) recommend that, in Stage 5 CKD, the target levels for calcium (Ca) (corrected for serum albumin), phosphate (P), calcium x phosphate (CaxP) product and parathyroid hormone (PTH) levels should be maintained at 8.4-9.5 mg/dl, 3.5-5.5 mg/dl, <55 mg2/dl2 and 150-300 pg/ml, respectively.

OBJECTIVES

To evaluate our ability to achieve K/DOQI guidelines for bone metabolism and disease targets in our patients and to compare them between patients on hemodialysis (HD) and peritoneal dialysis (PD) and also with those reported in the literature.

METHODS

We reviewed bone metabolism laboratory parameters in 57 HD patients and 69 PD patients, who had been on dialysis for more than 9 months.

RESULTS

The percentage of patients whose serum Ca, P, CaxP product and PTH were within K/DOQI recommended target ranges were 46%, 53%, 77% and 28% in HD patients and 52%, 65%, 77% and 23% in PD patients, respectively. There were no significant differences between HD and PD patients in the percentage of all parameters that were within K/DOQI recommended target ranges. The percentage of our HD patients who had Ca, P, and PTH levels within recommended target range was similar to those in previous reports.

CONCLUSION

In our unit, the management of bone and mineral metabolism in HD and PD patients is still far short of meeting K/DOQI guidelines. These findings appear similar in HD and PD patients. Our findings resemble those reported in the literature.

Long-Term Evolution of Body Composition After Renal Transplantation: 5-Year Survey

BACKGROUND

Thanks to advancements in immunosuppression, patients are living longer with kidney transplants, and nonimmunologic factors (particularly nutritional) have become a major source of morbidity and mortality after successful kidney transplantation (KTx). In this current study, we have prospectively assessed, in a cohort of kidney transplant recipients (KTR), the course of some nonimmunologic factors liable to hinder the long-term outcome of KTR.

METHODS

Forty-four consecutive KTR with stable functioning grafts received dietary recommendations and were on the lowest effective dose of steroids. Biochemical nutritional markers, C-reactive protein, lipid profile, and body composition determined by dual-energy X-ray absorptiometry were studied over the first year, 2 years, and 5 years after KTx.

RESULTS

No patients died during the follow-up. All patients but 2 were considered normotensive. Clinical diabetes developed in 3 patients. Visceral proteins stabilized at a normal range after the first year. Most of the patients normalized their inflammatory status. A significant improvement in lipid profile was observed. Female patients had a significant increase of weight (13.5%), mainly because of an increase in fat mass: 3.4 kg (19.4%) at 1 year and 5.6 kg (29.7%) at 2 years. In male patients, body composition remained stable and close to baseline values. The evolution of bone mass varied according to gender, total corticoid doses, and calcineurin inhibitors. Patients on low doses of steroids normalized their Z-score over the 5-year period. The increase in bone mass (paired t-test, P = .006) was only significant in patients treated with tacrolimus (analysis of variance for repeated measures, P < .001).

CONCLUSIONS

Simple measures and dietary intervention to prevent or correct nonimmunologic disorders should permit improvement of long-term morbidity and mortality of KTR without compromising the functional outcome of their transplant.

Paricalcitol [19-nor-1,25-(OH)2D2] in the treatment of experimental renal bone disease

Paricalcitol is a less hypercalcemic vitamin D analog that has been shown to suppress secondary hyperparathyroidism and to prevent the associated histomorphometric changes in bone. In this study, we show that paricalcitol also ameliorates the renal insufficiency-induced loss of bone mineral and the mechanical competence of bone.

INTRODUCTION

Renal bone disease is a common consequence of chronic renal insufficiency and the associated secondary hyperparathyroidism (SH). Paricalcitol [19-nor-1,25(OH)(2)D(2)] has been shown to ameliorate SH and prevent renal failure-induced histomorphometric changes in bone with minimal calcemic and phosphatemic activity. However, information about its efficacy on restoration of bone structural strength is lacking. In this study, we explored the effects of paricalcitol treatment on bone structure and strength in a model of advanced renal disease.

MATERIALS AND METHODS

Forty-five 8-week-old rats were randomly assigned to either surgical 5/6 nephrectomy (NTX) or Sham-operation. After a 15-week postoperative disease progression period, the NTX rats were further allocated to uremic control (NTX) and treatment (NTX + paricalcitol) groups, the latter of which received paricalcitol for the subsequent 12 weeks. After 27 weeks, the animals were killed, plasma samples were collected, and both femora were excised for comprehensive analysis of the femoral neck and midshaft (pQCT and biomechanical testing).

RESULTS

High mortality that exceeded 30% was observed in both NTX groups. NTX induced over a 13-fold increase in plasma PTH, whereas this increase was only 5-fold after paricalcitol treatment. At the femoral neck, NTX was associated with an 8.1% decrease (p < 0.05) in vBMD and a 16% decrease in breaking load (p < 0.05) compared with the Sham group, whereas paricalcitol treatment completely prevented these changes. At the femoral midshaft, the NTX resulted in a 6.6% decrease in cortical BMD (p < 0.01 versus Sham), and this change was also prevented by paricalcitol.

CONCLUSIONS

Paricalcitol administration prevented renal insufficiency-associated decreases in BMD in the femoral neck and the femoral midshaft and restored bone strength in the femoral neck. Therefore, paricalcitol can efficiently ameliorate renal insufficiency-induced loss of bone mineral and mechanical competence of bone.

Safety and efficacy of atorvastatin in patients with severe renal dysfunction

OBJECTIVE

To investigate the efficacy and safety of a daily dose of 10 mg of atorvastatin in patients with chronic kidney disease (CKD) stages 4 and 5 and a glomerular filtration rate of <30 ml/min.

MATERIAL AND METHODS

This was an open, prospective, randomized study. A total of 143 patients were included: 73 were controls and 70 were prescribed 10 mg/day of atorvastatin. As efficacy variables, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol and triglyceride levels were determined at the start of the study and at 1, 3, 6, 12, 18, 24, 30 and 36 months.

RESULTS

The follow-up period was a mean of 20+/-14.4 months (range 1-36 months) for those on atorvastatin versus 22+/-12.7 months (range 0.5-36 months) for the controls. Compared with baseline values, patients treated with atorvastatin had significantly lower concentrations of total cholesterol at Month 36 (5.8 vs 4.4 mmol/l; -23%; p<0.001), of LDL cholesterol at Month 36 (3.6 vs 2.2 mmol/l; -35%; p<0.001) and of triglycerides at Months 24 (2.5 vs 1.9 mmol/l) and 36 (2.5 vs 1.8 mmol/l). The controls had significantly reduced levels of total cholesterol at Month 36 (p<0.21) and of LDL cholesterol at Months 30 and 36. Compared with the controls, the atorvastatin group had lower levels of total cholesterol and LDL cholesterol at Months 1-30. Fifteen patients (21%) stopped taking their medication as they could not tolerate the side-effects, the most frequent complaints being gastrointestinal discomfort and headache.

CONCLUSION

Although the medication caused no severe adverse events, we recommend caution when using atorvastatin for severe CKD patients until further evidence of its safety and efficacy is verified.

Bone mineral density and its correlation with clinical and laboratory factors in chronic peritoneal dialysis patients

The aim of this study was to assess the clinical and laboratory correlations of bone mineral density (BMD) measurements among a large population of patients on chronic peritoneal dialysis (PD). This cross-sectional, multicenter study was carried out in 292 PD patients with a mean age of 56 +/- 16 years and mean duration of PD 3.1 +/- 2.1 years. Altogether, 129 female and 163 male patients from 24 centers in Canada, Greece, and Turkey were included in the study. BMD findings, obtained by dual-energy X-ray absorptiometry (DEXA) and some other major clinical and laboratory indices of bone mineral deposition as well as uremic osteodystrophy were investigated. In the 292 patients included in the study, the mean lumbar spine T-score was -1.04 +/- 1.68, the lumbar spine Z-score was -0.31 +/- 1.68, the femoral neck T-score was -1.38 +/- 1.39, and the femoral neck Z score was -0.66 +/- 1.23. According to the WHO criteria based on lumbar spine T-scores, 19.2% of 292 patients were osteoporotic, 36.3% had osteopenia, and 44.4% had lumbar spine T-scores within the normal range. In the femoral neck area, the prevalence of osteoporosis was slightly higher (26%). The prevalence of osteoporosis was 23.3% in female patients and 16.6% in male patients with no statistically significant difference between the sexes. Agreements of lumbar spine and femoral neck T-scores for the diagnosis of osteoporosis were 66.7% and 27.3% and 83.3% for osteopenia and normal BMD values, respectively. Among the clinical and laboratory parameters we investigated in this study, the body mass index (BMI) (P < 0.001), daily urine output, and urea clearance time x dialysis time/volume (Kt/V) (P < 0.05) were statistically significantly positive and Ca x PO(4) had a negative correlation (P < 0.05) with the lumbar spine T scores. Femoral neck T scores were also positively correlated with BMI, daily urine output, and KT/V; and they were negatively correlated with age. Intact parathyroid hormone levels did not correlate with any of the BMD parameters. Femoral neck Z scores were correlated with BMI (P < 0.001), and ionized calcium (P < 0.05) positively and negatively with age, total alkaline phosphatase (P < 0.05), and Ca x P (P < 0.01). The overall prevalence of fractures since the initiation of PD was 10%. Our results indicated that, considering their DEXA-based BMD values, 55% of chronic PD patients have subnormal bone mass-19% within the osteoporotic range and 36% within the osteopenic range. Our findings also indicate that low body weight is the most important risk factor for osteoporosis in chronic PD patients. An insufficient dialysis dose (expressed as KT/V) and older age may also be important risk factors for osteoporosis of PD patients.

Vitamin D in chronic kidney disease: A systemic role for selective vitamin D receptor activation

Hyperparathyroidism occurs in most patients during the progression of chronic kidney disease (CKD) and one of its initiating events, reduced serum levels of 1,25-dihydroxyvitamin D, results from a decrease in renal 1alpha hydroxylase activity, which converts 25-hydroxyvitamin D to its activated form. The combination of persistently high parathyroid hormone (PTH) and low 1,25-dihydroxyvitamin D is associated with bone loss, cardiovascular disease, immune suppression and increased mortality in patients with end-stage kidney failure. Recent studies in dialysis patients suggest that paricalcitol, a selective activator of the vitamin D receptor (VDR), is associated with a more favorable efficacy to side effect profile than calcitriol, with less morbidity and better survival. One hypothesis derived from such studies suggests that systemic activation of VDRs may have direct effects on the cardiovascular system to decrease mortality in CKD. Although current guidelines for regulating serum calcium, phosphate and PTH recommend specific interventions at the various stages of CKD to prevent or postpone irreversible parathyroid disease and decrease cardiovascular morbidity and mortality, emerging data suggest that vitamin D therapy may prolong survival in this patient population by mechanisms that are independent of calcium, phosphate and PTH. It is suggested that a re-evaluation of current treatment recommendations is needed and that future research should focus on mechanisms that distinguish potential tissue specific benefits of selective VDR activators in patients with CKD.

Fetuin-A and extraosseous calcification in uremia

PURPOSE OF REVIEW

It has become increasingly clear that vascular calcification, as part of accelerated uremic atherosclerosis, may powerfully predict mortality in the dialysis population. Secondary hyperparathyroidism and its consequences explain part of this phenomenon; however, serum concentrations of calcium and phosphate ions exceed their solubility product in an aqueous solution and must be prevented from precipitation by additional mechanisms. Fetuin-A is an inflammation-related calcium-regulatory glycoprotein acting as a systemic calcification inhibitor. The emerging role of fetuin-A deficiency as a risk factor in dialysis patients was documented in a cross-sectional study demonstrating a significant correlation with all-cause and cardiovascular mortality.

RECENT FINDINGS

In-vitro studies in vascular smooth muscle cells revealed that fetuin-A interacts directly with matrix vesicle release and may thus modulate vascular calcification processes locally and at early stages. Accordingly, prominent fetuin-A staining of calcified vessel segments obtained from uremic patients, in the absence of local expression, emphasizes its potential role as a circulating defense against overwhelming calcification. While increased fetuin-A levels positively correlated with vascular calcification in patients with diabetes and mild to moderate renal impairment, an inverse relationship was observed in dialysis patients. Both chronic inflammation and uremia may thus contribute to exhausting fetuin-A release in the late stages of kidney disease. Specific polymorphisms of the fetuin-A gene may be additional determinants of fetuin-A deficiency.

SUMMARY

Deficiencies of calcification inhibitors such as fetuin-A are relevant pathomechanisms in the progression of uncontrolled vascular calcification and may offer potential for future therapeutic approaches.

Clinical impact of preexisting vascular calcifications on mortality after renal transplantation

BACKGROUND

Vascular calcifications (VC) are a well-known cardiovascular risk factor (CVRF) in uremic patients. However, their role on mortality after renal transplantation (RT) is unclear.

METHODS

In 1117 RT recipients, we investigated the association between long-term survival and the presence of VC, evaluated by preoperative posteroanterior plain radiography from aorto-iliac region, at the time of RT. The primary study outcome was all-cause mortality. Other perioperative CVRF were also collected.

RESULTS

VC were observed in 273 patients (24.4%) before RT; additionally, 132 (12%) patients died during follow-up, due, mainly, to cardiovascular (39%) or infectious (24%) complications. As expected, patients with VC showed a higher age and a greater number of CVRF than those without VC. Overall mortality rate was also higher in VC group (19 vs. 9.5%; P= 0.0001), as well as cardiovascular mortality (9.5 vs. 3.1; P= 0.048). Multivariate Cox model showed that VC were predictor of overall mortality [relative risk (RR) 1.8; 95% CI 1.1-2.8; P= 0.015] and cardiovascular mortality (RR 2.6; 95%CI 1.1-6); P= 0.033), independently of other CVRF. An interaction between the presence of VC and diabetes was found. The effect of VC on mortality was evident in nondiabetic patients, that is, those with VC had a significantly higher mortality rate than patients without VC (21 vs. 9%; P= 0.0001). By contrast, these differences were not observed in diabetic patients (16.5 vs. 14.3%; P= 0.656).

CONCLUSION

VC evaluated by a simple and inexpensive plain radiography are an independent predictor of cardiovascular and all-cause mortality following RT. This finding may encourage the implementation of appropriate therapeutic strategies after RT.

A report with consensus statements of the International Society of Nephrology 2004 Consensus Workshop on Prevention of Progression of Renal Disease, Hong Kong, June 29, 2004

This report summarizes the discussions of the International Society of Nephrology (ISN) 2004 Consensus Workshop on Prevention of Progression of Renal Disease, which was held in Hong Kong on June 29, 2004. Three key areas were discussed during the workshop: (1) screening for chronic kidney disease; (2) evaluation and estimating progression of chronic kidney disease; and (3) measures to prevent the progression of chronic kidney disease. Fifteen consensus statements were made in these three areas, as endorsed by the participants of the workshop. The ISN can make use of and take reference to these statements in formulating its policy for tackling chronic kidney disease, a disease with significant global impact.

K/DOQI Guidelines for Bone Metabolism and Disease in Chronic Kidney Disease Patients: Some Therapeutic Implications

The National Kidney Foundation (NKF) has recently published clinical practice guidelines for bone metabolism and disease in chronic kidney disease (CKD) patients (the Kidney Disease Outcomes Quality Initiative [K/DOQI]). Data from the literature show that the majority of dialysis patients treated with traditional calcium-containing phosphorus binders and vitamin D or vitamin D analogue preparations have serum parathyroid hormone (PTH), calcium, and phosphorus levels outside these strict K/DOQI target ranges. In fact, it appears that achieving and maintaining the targets values set by these guidelines is virtually impossible without the simultaneous use of the new calcimimetic agents and non-calcium-containing binders, agents that have significant cost barriers to their use in many patients. These guidelines are welcome, but they may be impractical for the majority of dialysis patients. The impact of these guidelines in improving the parameters of bone metabolism and disease among dialysis patients remains to be determined.

Comparison of two formulae for estimation of glomerular filtration rate in children

Glomerular filtration rate (GFR) was measured in 216 studies in 151 children using the cimetidine protocol. This was compared with the GFR calculated using Léger's pharmacokinetic equation and with that calculated using k*L/[Cr](s )(constant x length in centimeters divided by serum creatinine concentration). The GFR calculated using the equation GFR=k*L/[Cr](s) yielded a closer approximation to the measured GFR than that using Léger's pharmacokinetic equation. Currently there is focus on screening children for decreased GFR to identify those with asymptomatic chronic kidney disease at a time when intervention may delay progression to chronic renal failure. This study showed close approximation of the calculated GFR with the measured GFR using the equation GFR=k*L/[Cr](s), when the values for k were determined in the laboratory in which creatinine was measured.