Association of hyperphosphataemia with haemodynamic disturbances in end-stage renal disease

Seeing the Whole Picture: Evaluating the Contribution of Whole Grains to Phosphorus Exposure in People With Kidney Failure Undergoing Dialysis Treatment

Excessive dietary phosphorus is a concern among patients with kidney failure undergoing dialysis treatment because it may contribute to hyperparathyroidism and hyperphosphatemia. A long-standing but untested component of the low-phosphorus diet is the promotion of refined grains over whole grains. This paper reviews the scientific premise for restricting whole grains in the dialysis population and estimates phosphorus exposure from grain products based on three grain intake patterns modeled from reported intakes in the general US population, adjusting for the presence of phosphorus additives and phosphorus bioavailability: (1) standard grain intake, (2) 100% refined grain intake, and (3) mixed (50/50 whole and refined grain) intake. Although estimated phosphorus exposure from grains was higher with the mixed grain pattern (231 mg/day) compared to the 100% refined grain pattern (127 mg/day), the amount of additional phosphorus from grains was relatively low. Given the lack of strong evidence for restricting whole grains in people with CKD, as well as the potential health benefits of whole grains, clinical trials are warranted to address the efficacy and health impact of this practice.

Target phosphate and calcium levels in patients undergoing hemodialysis: a post-hoc analysis of the LANDMARK study

BACKGROUND

It is necessary to re-examine the optimal phosphate (P) and calcium (Ca) target values in the contemporary management of chronic kidney disease-mineral and bone disorder to reduce the risks of cardiovascular events in patients receiving hemodialysis.

METHODS

We performed a post-hoc analysis of the LANDMARK study. The outcomes were defined as cardiovascular events and all-cause death. Data from 2135 patients receiving hemodialysis at risk of vascular calcification were analyzed using a time-dependent Cox proportional hazard model adjusted for background factors.

RESULTS

On the hazard ratio (HR) curve, the ranges where the lower 95% confidence interval (CI) were below the minimum of HR (= 1.00) were as follows: P = 3.5-5.5 mg/dL; albumin-adjusted Ca < 9.1 mg/dL for cardiovascular events; and P = 3.6-5.3 mg/dL; albumin-adjusted Ca < 9.1 mg/dL for all-cause mortality. In stratified analysis, the HRs for cardiovascular events in P < 3.5 mg/dL and P ≥ 5.5 mg/dL were similar to that of P = 3.5-5.5 mg/dL (P ≥ 0.05), and albumin-adjusted Ca ≥ 9.1 mg/dL had higher HR than values < 9.1 mg/dL [1.30 (95% CI 1.00-1.68; P = 0.046)]. For all-cause mortality, the HR in P < 3.6 mg/dL was higher than that in P = 3.6-5.3 mg/dL [1.76 (95% CI 1.25-2.48; P = 0.001)], while the HRs between P ≥ 5.3 mg/dL and P = 3.6-5.3 mg/dL as well as those between albumin-adjusted Ca ≥ 9.1 and < 9.1 mg/dL were not significantly different (P ≥ 0.05).

CONCLUSIONS

Managing albumin-adjusted Ca < 9.1 mg/dL may reduce the cardiovascular risk among patients undergoing hemodialysis. Hypophosphatemia < 3.6 mg/dL may be associated with mortality.

Evaluation of cerium oxide as a phosphate binder using 5/6 nephrectomy model rat

BACKGROUND

The number of chronic kidney disease (CKD) patients continues to increase worldwide. CKD patients need to take phosphate binders to manage serum phosphorus concentrations. Currently, several types of phosphate binder, including lanthanum carbonate, are used. However, they each have disadvantages.

METHODS

In this study, we evaluated cerium oxide as a new phosphate binder in vitro and in vivo. First, cerium oxide was mixed with phosphoric acid at pH 2.5 or 7.0, and residual phosphoric acid was measured by absorption photometry using colorimetric reagent. Second, cerium oxide was fed to 5/6 nephrectomy model rats (5/6Nx), a well-known renal damage model. All rats were measured food intake, water intake, feces volume, and urine volume, and collected serum and urine were analyzed for biochemical markers.

RESULTS

Cerium oxide can adsorb phosphate at acidic and neutral pH, while lanthanum carbonate, which is a one of popular phosphate binder, does not dissolve at neutral pH. Cerium oxide-treatment reduced serum phosphate concentrations of 5/6Nx rats without an increase in serum alanine transaminase levels that would indicate hepatotoxicity, and cerium oxide-treatment maintained serum creatinine and blood urea nitrogen levels, while those of normal 5/6Nx rats increased slightly.

CONCLUSIONS

These results suggest that cerium oxide can be a potential phosphate binder. Decreased body weight gain and increased water intake and urine volume in 5/6Nx rats were thought to be an effect of nephrectomy because these changes did not occur in sham operation rats. Additional investigations are needed to evaluate the longer-term safety and possible accumulation of cerium oxide in the body.

IGF IIRα-triggered pathological manifestations in the heart aggravate renal inflammation in STZ-induced type-I diabetes rats

Pathological manifestations in either heart or kidney impact the function of the other and form the basis for the development of cardiorenal syndrome. However, the mechanism or factors involved in such scenario are not completely elucidated. In our study, to find the correlation between late fetal gene expression in diabetic hearts and their influence on diabetic nephropathy, we created a rat model with cardiac specific overexpression of IGF-IIRα, which is an alternative splicing variant of IGFIIR, expressed in pathological hearts. In this study, transgenic rats over expressing cardiac specific IGF-IIRα and non-transgenic animal models established in SD rats were administered with single dose of streptozotocin (STZ, 55 mg/Kg) to induce Type I diabetes. The correlation between IGF-IIRα and kidney damages were further determined based on their intensity of damage in the kidneys. The results show that cardiac specific overexpression of IGF-IIRα elevates the diabetes associated inflammation and morphological changes in the kidneys. The diabetic transgenic rats showed advancement in the pathological features such a renal tubular damage, collagen accumulation and enhancement in STAT3 associated mechanism of renal fibrosis. The results therefore show that that IGF-IIRα expression in the heart during pathological condition may worsen symptoms of diabetic nephropathy in rats.

Cardiovascular Benefits of Extended-Time Nocturnal Hemodialysis

Hemodialysis (HD) remains the most utilized treatment for End-Stage Kidney Disease (ESKD) globally, mainly as conventional HD administered in 4 h sessions thrice weekly. Despite advances in HD delivery, patients with ESKD carry a heavy cardiovascular morbidity and mortality burden. This is associated with cardiac remodeling, left ventricular hypertrophy (LVH), myocardial stunning, hypertension, decreased heart rate variability, sleep apnea, coronary calcification and endothelial dysfunction. Therefore, intensive HD regimens closer to renal physiology were developed. They include longer, more frequent dialysis or both. Among them, Nocturnal Hemodialysis (NHD), carried out at night while asleep, provides efficient dialysis without excessive interference with daily activities. This regimen is closer to the physiology of the native kidneys. By providing increased clearance of small and middle molecular weight molecules, NHD can ameliorate uremic symptoms, control hyperphosphatemia and improve quality of life by allowing a liberal diet and free time during the day. Lastly, it improves reproductive biology leading to successful pregnancies. Conversion from conventional to NHD is followed by improved blood pressure control with fewer medications, regression of LVH, improved LV function, improved sleep apnea, and stabilization of coronary calcifications. These beneficial effects have been associated, among others, with better extracellular fluid volume control, improved endothelial- dependent vasodilation, decreased total peripheral resistance, decreased plasma norepinephrine levels and restoration of heart rate variability. Some of these effects represent improvements in outcomes used as surrogates of hard outcomes related to cardiovascular morbidity and mortality. In this review, we consider the cardiovascular effects of NHD.

Regulation of Vascular Calcification by Reactive Oxygen Species

Vascular calcification is the deposition of hydroxyapatite crystals in the medial or intimal layers of arteries that is usually associated with other pathological conditions including but not limited to chronic kidney disease, atherosclerosis and diabetes. Calcification is an active, cell-regulated process involving the phenotype transition of vascular smooth muscle cells (VSMCs) from contractile to osteoblast/chondrocyte-like cells. Diverse triggers and signal transduction pathways have been identified behind vascular calcification. In this review, we focus on the role of reactive oxygen species (ROS) in the osteochondrogenic phenotype switch of VSMCs and subsequent calcification. Vascular calcification is associated with elevated ROS production. Excessive ROS contribute to the activation of certain osteochondrogenic signal transduction pathways, thereby accelerating osteochondrogenic transdifferentiation of VSMCs. Inhibition of ROS production and ROS scavengers and activation of endogenous protective mechanisms are promising therapeutic approaches in the prevention of osteochondrogenic transdifferentiation of VSMCs and subsequent vascular calcification. The present review discusses the formation and actions of excess ROS in different experimental models of calcification, and the potential of ROS-lowering strategies in the prevention of this deleterious condition.

Blood Pressure and Left Ventricular Hypertrophy in Patients on Different Peritoneal Dialysis Regimens

Objective

To examine the relation between the results of ambulatory 24-hour blood pressure monitoring (ABPM) and left ventricular mass index (LVMI), then to find the independent determinant for left ventricular hypertrophy (LVH) in peritoneal dialysis (PD) patients. Finally, to evaluate the differences in the clinical and cardiovascular characteristics between patients on continuous ambulatory PD (CAPD) and continuous cyclic PD (CCPD).

Design

An open, nonrandomized, cross-sectional study.

Setting

Divisions of nephrology and cardiology in a medical center.

Patients

Thirty-two uremic patients on maintenance PD therapy (22 patients on CAPD, and 10 on CCPD) without anatomical heart disease or history of receiving long-term hemodialysis.

Interventions

Home blood pressure (BP) and office BP were measured using the Korotkoff sound technique by sphygmomanometer. ABPM was employed for continuous measurement of BP. Echocardiography was performed for measurement of cardiac parameters and calculation of LVMI.

Main Outcome Measures

Multivariate logistic regression analysis was performed for independent determinant of LVH in PD patients. The differences in clinical and cardiovascular characteristics between CAPD and CCPD patients were compared.

Results

Simple regression analysis showed positive correlations between LVMI and the duration of hypertension, ambulatory nighttime BP/BP load/BP load > 30%, serum phosphate, calcium–phosphate product, ultrafiltration (UF) volume, and percentage of UF volume during the nighttime. A negative correlation was noted between LVMI and dipping. In multiple regression analysis, the duration of hypertension was the only variable linked to LVMI. In multivariate logistic regression analysis, only ambulatory nighttime systolic BP load > 30% had an independent association with LVH. There were correlations between office/home BP and ambulatory 24-hour BP. In addition, CCPD patients had higher LVMI, UF volume during the nighttime, and percentage of UF volume during the nighttime than those of CAPD patients.

Conclusions

In this study, ambulatory nighttime systolic BP load > 30% had an independent association with LVH. Office and home BP measurements were correlated with ABPM in PD patients. The result that CCPD patients had a higher LVMI than CAPD patients may be due to a relative volume overload during the daytime in CCPD patients.

The role of phosphate-containing medications and low dietary phosphorus-protein ratio in reducing intestinal phosphorus load in patients with chronic kidney disease

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a common complication in patients experiencing end-stage renal disease (ESRD). It includes abnormalities in bone and mineral metabolism and vascular calcification. Hyperphosphatemia is a major risk factor leading to morbidity and mortality in patients with chronic kidney disease. Increased mortality has been observed in patients with ESRD, with serum phosphorus levels of >5.5 mg/dL. Therefore, control of hyperphosphatemia is a major therapeutic goal in the prevention and treatment of CKD-MBD. The treatment of hyperphosphatemia includes decreasing intestinal phosphorus load and increasing renal phosphorus removal. Decreasing the intestinal load of phosphorus plays a major role in the prevention and treatment of CKD-MBD. Among the dietary sources of phosphorus, some of the commonly prescribed medications have also been reported to contain phosphorus. However, drugs are often ignored even though they act as a potential source of phosphorus. Similarly, although proteins are the major source of dietary phosphorus, reducing protein intake can increase mortality in patients with CKD. Recently, the importance of phosphorus/protein ratio in food have been reported to be a sensitive marker for controlling dietary intake of phosphorus. This review summarizes the progress in the research on phosphate content in drugs as an excipient and the various aspects of dietary management of hyperphosphatemia in patients with CKD, with special emphasis on dietary restriction of phosphorus with low dietary phosphate/protein ratio.

Phosphatemic Control during Acute Renal Failure: Intermittent Hemodialysis versus Continuous Hemodiafiltration

Background

Achieving “adequacy of dialysis” includes the maintenance of normal serum phosphate concentrations and is an important therapeutic goal in the treatment of acute renal failure (ARF). It is unknown whether this goal is best achieved with intermittent or continuous renal replacement therapy.

Methods

We compared the effects of continuous veno-venous hemodiafiltration (CVVHDF) and intermittent hemodialysis (IHD) on serum phosphate concentrations using daily morning blood tests in 88 consecutive intensive care patients half of which were treated with IHD and half with CRRT.

Results

Mean patient age was 54 ± 14 years for IHD and 60 ± 14 years for CVVHDF (NS). However, patients who received CVVHDF were more critically ill (mean APACHE II scores: 24.4 ± 5.1 for IHD vs. 29.2 ± 5.7 for CVVHDF, p<0.003). Before treatment, the serum phosphate concentration was 2.04 ± 0.16 mmoll L for IHD and 1.96 ± 0.17 mmoll L for CVVHDF (NS), with abnormal values in 79.4% of IHD patients and in 64.8% of CVVHDF patients (NS). During treatment, CVVHDF induced a greater reduction in serum phosphate (p=0.02) during the first 48 hours and conferred superior subsequent control of hyperphosphatemia (achieved in 64.6% of observations during CVVHDF vs. 41.8% during IHD; p<0.0001). The serum phosphate concentration was also more likely to be within the normal range during CVVHDF (55.3% vs.36.2%; p<0.0001). There was a trend toward more frequent hypophosphatemia (9.3% vs. 5.6%; P<0.1) during CVVHDF.

Conclusions

Abnormal serum phosphate concentrations are frequent in ARF patients before and during renal replacement, however, normalization of phosphatemia is achieved more frequently with CVVHDF.

Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia

Background

Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease.

Scope

A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent-to-treat population (N=2520), 752 patients with recorded dose data for calcium acetate (n=551)/calcium carbonate (n=201) at baseline and lanthanum carbonate at week 16 were studied. Elemental calcium intake, serum phosphate, corrected serum calcium, and serum intact parathyroid hormone levels were analyzed.

Findings

Of the 551 patients with calcium acetate dose data, 271 (49.2%) had an elemental calcium intake of at least 1.5 g/day at baseline, and 142 (25.8%) had an intake of at least 2.0 g/day. Mean (95% confidence interval [CI]) serum phosphate levels were 6.1 (5.89, 6.21) mg/dL at baseline and 6.2 (6.04, 6.38) mg/dL at 16 weeks; mean (95% CI) corrected serum calcium levels were 9.3 (9.16, 9.44) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Of the 201 patients with calcium carbonate dose data, 117 (58.2%) had an elemental calcium intake of at least 1.5 g/day, and 76 (37.8%) had an intake of at least 2.0 g/day. Mean (95% CI) serum phosphate levels were 5.8 (5.52, 6.06) mg/dL at baseline and 5.8 (5.53, 6.05) mg/dL at week 16; mean (95% CI) corrected serum calcium levels were 9.7 (9.15, 10.25) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively.

Conclusion

Calcium acetate/calcium carbonate phosphate binders, taken to control serum phosphate levels, may result in high levels of elemental calcium intake. This may lead to complications related to calcium balance.

Electrolytes and Fluid Management in Hemodialysis and Peritoneal Dialysis

The kidney is a complex and vital organ, regulating the electrolyte and fluid status of the human body. As hemodialysis (HD) and peritoneal dialysis (PD) are forms of renal replacement therapy and not an actual kidney, they do not possess the same physiologic regulation of both fluid and electrolytes. Precise regulation of fluid and electrolytes in the HD and PD population remains a constant challenge. In this review, fluid status of both HD and PD will be examined, as well as sodium, potassium, phosphorous, and calcium. Each electrolyte will be analyzed by its physiological significance, the complications that arise when a proper balance cannot be maintained, and methods to correct these imbalances. An overview of the fluid compartments and volume of distribution within the body will be discussed. Ultrafiltration, a modality used in both forms of renal replacement therapy, will be defined, along with its impact on fluid status. Fluid assessment will be addressed, along with proper maintenance of fluid homeostasis. By having an understanding of the pathophysiology behind the fluid and electrolyte abnormalities that occur in end-stage renal disease, one can direct proper management with medications, diet, and alterations in dialysis to provide patients with the most optimal form of renal replacement therapy available.

Left Ventricular Hypertrophy in Chronic Kidney Disease Patients: From Pathophysiology to Treatment

Cardiovascular diseases represent the main causes of morbidity and mortality in patients with chronic kidney disease (CKD). According to a well-established classification, cardiovascular involvement in CKD can be set in the context of cardiorenal syndrome type 4. Left ventricular hypertrophy (LVH) represents a key feature to provide an accurate picture of systolic-diastolic left heart involvement in CKD patients. Cardiovascular involvement is present in about 80% of prevalent hemodialysis patients, and it is evident in CKD patients since stage IIIb-IV renal disease (according to the K/DOQI CKD classification). According to the definition of cardiorenal syndrome type 4, kidney disease is detected before the development of heart failure, although timing of the diagnosis is not always possible. The evaluation of LVH is a bit heterogeneous, and few standard imaging methods can provide the accuracy of either CT- or MRI-derived left ventricular mass. Key principles in the treatment of LVH in CKD patients are mainly based on anemia and blood pressure control, together with the management of secondary hyperparathyroidism and sudden cardiac death prevention. This review is mainly focused on the clinical aspects of CKD-related LVH to provide practical guidelines both for cardiologists and nephrologists in the daily clinical approach to CKD patients.

Hyperphosphatemia Management in Patients with Chronic Kidney Disease

Hyperphosphatemia in chronic kidney disease (CKD) patients is a potentially life altering condition that can lead to cardiovascular calcification, metabolic bone disease (renal osteodystrophy) and the development of secondary hyperparathyroidism (SHPT). It is also associated with increased prevalence of cardiovascular diseases and mortality rates. To effectively manage hyperphosphatemia in CKD patients it is important to not only consider pharmacological and nonpharmacological treatment options but also to understand the underlying physiologic pathways involved in phosphorus homoeostasis. This review will therefore provide both a background into phosphorus homoeostasis and the management of hyperphosphatemia in CKD patients. In addition, it will cover some of the most important reasons for failure to control hyperphosphatemia with emphasis on the effect of the gastric pH on phosphate binders efficiency.

Serum phosphorus levels and pill burden are inversely associated with adherence in patients on hemodialysis

BACKGROUND

Phosphate binders (PBs) account for about one half of the daily pill burden for US hemodialysis (HD) patients, which may reduce adherence. Adherence can be estimated by the medication possession ratio (MPR), which is defined as the proportion of time a patient had sufficient medication to have taken it as prescribed. Gaps of time between prescription fills lower the patient's MPR. We assessed the association of PB pill burden and adherence (MPR) with phosphorus goal attainment.

METHODS

Using pharmacy management program data, HD patients on PB monotherapy were tracked from first PB fill during 1 January 2007-30 June 2011 for 1 year, or until PB change or censoring. Data were assessed with generalized linear models.

RESULTS

We analyzed 8616 patients. Higher pill burden was associated with lower adherence. Lower adherence tended to be associated with higher mean phosphorus levels and lower percentage of patients with serum phosphorus ≤5.5 mg/dL (P < 0.001). The association between adherence and these clinical outcomes was most pronounced in the lowest and highest pill burden strata (<3, >3-6, >12-15, >15).

CONCLUSIONS

Adherence, as measured by the MPR, was negatively related to higher pill burden and phosphorus levels and positively related to patients in the phosphorus target range. Within pill burden strata, phosphorus increased and patients in the target range generally decreased with decreasing adherence, suggesting that patients prescribed fewer PB pills are less likely to have treatment gaps, and may be more likely to achieve phosphorus targets.

Heart failure in patients with chronic kidney disease: a systematic integrative review

Introduction. Heart failure (HF) is highly prevalent in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) and is strongly associated with mortality in these patients. However, the treatment of HF in this population is largely unclear. Study Design. We conducted a systematic integrative review of the literature to assess the current evidence of HF treatment in CKD patients, searching electronic databases in April 2014. Synthesis used narrative methods. Setting and Population. We focused on adults with a primary diagnosis of CKD and HF. Selection Criteria for Studies. We included studies of any design, quantitative or qualitative. Interventions. HF treatment was defined as any formal means taken to improve the symptoms of HF and/or the heart structure and function abnormalities. Outcomes. Measures of all kinds were considered of interest. Results. Of 1,439 results returned by database searches, 79 articles met inclusion criteria. A further 23 relevant articles were identified by hand searching. Conclusions. Control of fluid overload, the use of beta-blockers and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and optimization of dialysis appear to be the most important methods to treat HF in CKD and ESRD patients. Aldosterone antagonists and digitalis glycosides may additionally be considered; however, their use is associated with significant risks. The role of anemia correction, control of CKD-mineral and bone disorder, and cardiac resynchronization therapy are also discussed.

Mineral metabolism abnormalities and vitamin D receptor activation in cardiorenal syndromes

Over the last decade, it has become increasingly clear that the cardiovascular and renal systems are interdependent. Primary disorders of either system have been shown to disturb the other system. As a result, a class of cardiorenal syndromes (CRS) has been identified wherein a vicious cycle is established as an acute/chronic dysfunction of either the kidney or the heart exacerbates the loss of function in the other organ. Progressive loss of kidney function observed in patients with CRS (mostly types 2 and 4) leads to reduced production of calcitriol (active vitamin D) and an imbalance in calcium and phosphorus levels, which are correlated with increased rates of cardiovascular events and mortality. In addition, hypocalcemia can lead to prolonged and excessive secretion of parathyroid hormone (PTH), eventually leading to development of secondary hyperparathyroidism. Therefore, based on this important mechanism of organ damage, one of the major goals of therapy for patients with CRS is to restore regulatory control of PTH. Although administration of calcitriol increases serum calcium levels and reduces PTH levels, it is also associated with elevated serum levels of calcium-phosphorus product. Therefore, compounds that selectively activate vitamin D receptors, potentially reducing calcium × phosphate toxicity, are likely to enhance cardiorenal protection and provide significant clinical benefit.

Mineral metabolic abnormalities and mortality in dialysis patients

The survival rate of dialysis patients, as determined by risk factors such as hypertension, nutritional status, and chronic inflammation, is lower than that of the general population. In addition, disorders of bone mineral metabolism are independently related to mortality and morbidity associated with cardiovascular disease and fracture in dialysis patients. Hyperphosphatemia is an important risk factor of, not only secondary hyperparathyroidism, but also cardiovascular disease. On the other hand, the risk of death reportedly increases with an increase in adjusted serum calcium level, while calcium levels below the recommended target are not associated with a worsened outcome. Thus, the significance of target levels of serum calcium in dialysis patients is debatable. The consensus on determining optimal parathyroid function in dialysis patients, however, is yet to be established. Therefore, the contribution of phosphorus and calcium levels to prognosis is perhaps more significant. Elevated fibroblast growth factor 23 levels have also been shown to be associated with cardiovascular events and death. In this review, we examine the associations between mineral metabolic abnormalities including serum phosphorus, calcium, and parathyroid hormone and mortality in dialysis patients.

Higher serum osteocalcin is associated with lower abdominal aortic calcification progression and longer 10-year survival in elderly men of the MINOS cohort

CONTEXT

Abdominal aortic calcification (AAC) is an indicator of cardiovascular risk, especially in the diseases characterized by insulin resistance such as type 2 diabetes. Osteocalcin is a bone-secreted hormone that favors insulin sensitivity and insulin secretion.

OBJECTIVES

We investigated whether total serum osteocalcin level at baseline is associated with AAC progression and 10-year all-cause mortality in elderly men.

DESIGN AND PARTICIPANTS

We assessed 774 men aged 51-85 years from the MINOS cohort who had osteocalcin measurement and lumbar spine radiographs at baseline. They were followed-up prospectively for 10 years. Among them, 615 patients had a follow-up radiograph at 3.5 or 7 years.

MAIN OUTCOME MEASURES

Serum total osteocalcin was measured with an immunoradiometric assay on morning fasting serum collected at baseline. Kauppila's AAC score was assessed from lumbar spine radiographs. AAC progression rate was calculated as the difference between AAC on the last available radiograph and AAC at baseline divided by the follow-up time. Death status was collected over 10 years.

RESULTS

In multivariate analysis, higher baseline total osteocalcin was associated with lower AAC progression rate (odds ratio = 0.74 [0.57-0.97] per 10 ng/mL variation; P = 0.029). At the 10-year follow-up, there were 599 men alive (77%), 181 dead (23%), and 2 lost to follow-up. Higher osteocalcin was associated with lower 10-year all-cause mortality (hazard ratio = 0.62 [0.44-0.86] per 10 ng/mL variation; P = 0.005).

CONCLUSION

Higher baseline total osteocalcin concentrations were associated with lower AAC progression rate and lower mortality. These data suggest that osteocalcin level might be an independent indicator of cardiovascular risk and global health in elderly Caucasian men.

FGF-23 is associated with cardiac troponin T and mortality in hemodialysis patients

Fibroblast growth factor 23 (FGF-23) is elevated in patients with end-stage kidney disease and has been linked with mortality, vascular calcification, markers of bone turnover, and left ventricular hypertrophy. In this cohort study, we determined the correlates of FGF-23 (including cardiac troponin T [cTNT]) and determined its association with mortality over 3.5 years of follow-up in 103 prevalent hemodialysis patients. Mean age was 61.2 (15.5) and the mean dialysis vintage was 4.19 years (4.6). The median (interquartile range) FGF-23 was 1259 (491, 2885) RU/mL. Independent predictors (estimate standard error) of log-transformed FGF-23 concentrations included phosphorus (0.75 [0.237], P = 0.002) and cardiac troponin T (1.04 [0.41], P = 0.01). There were 57 deaths. In the fully adjusted model, the significant predictors of mortality included age and albumin. The independent association between FGF-23 and cTNT is a novel finding. Whether this relationship supports the possibility that a downstream effect of dysregulated phosphorous homeostasis may be enhanced cardiac remodeling requires further study.

Cardiovascular risk factors in chronic kidney disease: does phosphate qualify?

Risk factors for disease states are rigorously defined. This analysis considers the definition of a risk factor as applied to the question of whether the serum phosphorus level is a risk factor for cardiovascular disease. Observational studies strongly suggest that phosphorus is associated with cardiovascular risk, and definitive prospective animal studies are supportive. A plausible mechanism of action has been discovered demonstrating that phosphorus stimulates osteoblastic transition of cells in the neointima of atherosclerotic plaques, which, if prevented, blocks vascular calcification. However, prospective studies demonstrating that modulation of the putative risk factor affects clinical outcomes are lacking, and phosphorus, as yet, does not qualify as a cardiovascular risk factor. This is a clarion call for additional research.

Evaluation of morbidity and mortality data related to cardiovascular calcification from calcium-containing phosphate binder use in patients undergoing hemodialysis

Cardiovascular disease is the leading cause of death among patients with stage 5 chronic kidney disease. Several mechanisms are thought to contribute to vascular calcification and subsequent cardiovascular disease in patients who require hemodialysis. One of these mechanisms is the use of calcium-containing phosphate binders to treat hyperphosphatemia. Although most phosphate binding occurs in the gastrointestinal tract, some calcium is inevitably absorbed and has the potential to perpetuate the calcium-phosphorus product and the development of vascular and soft tissue calcification. Some phosphate binders such as sevelamer hydrochloride do not contain calcium and therefore may not carry the same risks. We examined the cardiovascular calcification effect and morbidity and mortality data with calcium-containing phosphate binders compared with sevelamer hydrochloride when given to patients with stage 5 chronic kidney disease for the treatment of hyperphosphatemia. A literature search using the MEDLINE and PubMed databases identified relevant articles from 1989-2009; nine studies compared vascular calcification between a calcium-containing phosphate binder and sevelamer hydrochloride. Three mortality studies were also identified. Seven of the nine studies reported a statistically significant increase in vascular calcification in patients taking calcium-containing phosphate binders as measured by coronary artery calcification scores and aortic calcification scores. In two trials, lower mortality rates were observed in the patients receiving sevelamer hydrochloride compared with calcium-containing phosphate binders. No significant difference in the mortality rate was observed in the third trial. Based on the current literature, it appears that calcium-containing phosphate binders promote the progression of vascular calcification to a greater extent than does sevelamer hydrochloride. In addition, some evidence suggests that sevelamer hydrochloride may reduce all-cause mortality rates in patients undergoing hemodialysis, particularly those aged 65 years or older. Thus, although sevelamer hydrochloride appears to be the more appropriate choice of phosphate binder for patients undergoing hemodialysis in whom cardiovascular calcification is a concern, more clinical trials are needed to further guide practitioners on the selection of phosphate binders.

Left ventricular mass in chronic kidney disease and ESRD

Chronic kidney disease (CKD) and ESRD, treated with conventional hemo- or peritoneal dialysis are both associated with a high prevalence of an increase in left ventricular mass (left ventricular hypertrophy [LVH]), intermyocardial cell fibrosis, and capillary loss. Cardiac magnetic resonance imaging is the best way to detect and quantify these abnormalities, but M-Mode and 2-D echocardiography can also be used if one recognizes their pitfalls. The mechanisms underlying these abnormalities in CKD and ESRD are diverse but involve afterload (arterial pressure and compliance), preload (intravascular volume and anemia), and a wide variety of afterload/preload independent factors. The hemodynamic, metabolic, cellular, and molecular mediators of myocardial hypertrophy, fibrosis, apoptosis, and capillary degeneration are increasingly well understood. These abnormalities predispose to sudden cardiac death, most likely by promotion of electrical instability and re-entry arrhythmias and congestive heart failure. Current treatment modalities for CKD and ESRD, including thrice weekly conventional hemodialysis and peritoneal dialysis and metabolic and anemia management regimens, do not adequately prevent or correct these abnormalities. A new paradigm of therapy for CKD and ESRD that places prevention and reversal of LVH and cardiac fibrosis as a high priority is needed. This will require novel approaches to management and controlled interventional trials to provide evidence to fuel the transition from old to new treatment strategies. In the meantime, key management principles designed to ameliorate LVH and its complications should become a routine part of the care of the patients with CKD and ESRD.

Association of calcium-phosphorus product with blood pressure in dialysis

Hypertension is very common in dialysis patients. Disorders of mineral metabolism have been linked to vascular calcification and hypertension in dialysis. Fifty-four hemodialysis patients were included in a cross-sectional study in a dialysis unit during a 6-month period. Linear regression analysis was done between averages of calcium and phosphorus (ca x ph) product and blood pressures (BPs). Ca x ph was significantly associated with systolic BP predialysis (P=.03, R=0.28), diastolic BP predialysis (P=.001, R=0.44), predialysis mean arterial pressure (MAP) (P=.002, R=0.4), and diastolic BP postdialysis (P=.03, R=0.26). No relationship was found with pulse pressures. Multilinear regression analysis was then done between ca x ph product and BPs adjusting for age, sex, hemoglobin, diabetes, albumin, parathyroid hormone, ultrafiltration volume, and average BP medications per patient. There was a strong positive association with predialysis systolic BP (P=.003, R(2)=0.49), predialysis MAP (P=.001, R(2)=0.51), and postdialysis MAP (P=.02, R(2)=0.65). No associations with pulse pressures were detected. The study findings suggest that ca x ph product is significantly associated with dialysis MAP and not pulse pressure. This is likely secondary to the stronger relationship with diastolic BP than with systolic BP. Prospective studies looking into the associated hemodynamic parameters related to arterial stiffness and endothelial dysfunction along with measures for calcifications would be very beneficial.

Absorption and excretion of colestilan in healthy subjects

Colestilan, an anion-exchange resin binding both phosphate and bile-acid anions, is under development for the treatment of hyperphosphataemia and dyslipidaemia, which occur in the majority of end-stage renal disease patients. This study using 14C-colestilan was conducted to investigate the absorption and excretion of colestilan in humans. Following a 28-day run-in period with administration of colestilan 3 g three times daily, 12 subjects received a single oral dose of 14C-colestilan 100 mg (approximately 4.0 MBq) and colestilan 3 g under fasted conditions on the morning of day 1. A total of 9 g of colestilan was administered three times daily on days 1-4. Total radioactivity levels in whole blood (at 4, 8, 12 and 24 hours and then at 24-hour intervals) and in the urine and faeces (from 0 to 24 hours and then at 24-hour intervals) were monitored up to 216 hours postdose (day 10). Total radioactivity measured in all whole-blood samples was below the lower limit of quantification (0.025 microg equivalent of 14C-labelled colestilan/mL of whole blood). Total radioactivity assessed in all urine samples was also below the lower limit of quantification (0.003 microg equivalent/mL for urine), except at 0-24 hours postdose, when 0.01% of the radioactive dose was excreted by all subjects. This level was below the predetermined water soluble impurity level of 0.04%. The mean cumulative excretion of total radioactivity in the faeces was 99.66% by 216 hours postdose, excluding one subject with incomplete collection of faecal samples. These results demonstrate that colestilan is not absorbed from the gastrointestinal tract and is completely excreted in the faeces.

Cinacalcet HCl and concurrent low-dose vitamin D improves treatment of secondary hyperparathyroidism in dialysis patients compared with vitamin D alone: the ACHIEVE study results

BACKGROUND AND OBJECTIVES

Patients with chronic kidney disease (CKD) receiving dialysis often develop secondary hyperparathyroidism with disturbed calcium and phosphorus metabolism. The National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (KDOQI) was established to guide treatment practices for these disorders. The ACHIEVE study was designed to test two treatment strategies for achieving KDOQI goals.

DESIGN, SETTING, PARTICIPANTS, MEASUREMENTS

Individuals on hemodialysis treated with vitamin D sterols were enrolled in this 33-week study. Subjects were randomly assigned to treatment with either cinacalcet and low-dose vitamin D (Cinacalcet-D) or flexible vitamin D alone (Flex-D) to achieve KDOQI-recommended bone mineral targets. ACHIEVE included a 6-week screening phase, including vitamin D washout, a 16-week dose-titration phase, and an 11-week assessment phase.

RESULTS

Of 173 subjects enrolled, 83% of Cinacalcet-D and 67% of Flex-D subjects completed the study. A greater proportion of Cinacalcet-D versus Flex-D subjects had a >30% reduction in parathyroid hormone (PTH) (68% versus 36%, P < 0.001) as well as PTH <300 pg/ml (44% versus 23%, P = 0.006). The proportion of subjects simultaneously achieving targets for intact PTH (150-300 pg/ml) and calcium-phosphorus product (Ca x P) (<55 mg2/dl2) was also greater (21% versus 14%), but this was not statistically significant. This was attributable to 19% of Cinacalcet-D subjects with a PTH value below the KDOQI target range.

CONCLUSIONS

Achievement of KDOQI targets was difficult, especially with Flex-D. Maintaining calcium and phosphorus target values precluded the use of vitamin D doses necessary to lower PTH to within the narrow target range and highlighted limitations inherent to the KDOQI treatment algorithm.

Phosphate binders in chronic kidney disease and end-stage renal disease: a patient-centered approach

Disorders of calcium and phosphorus metabolism are associated with significant morbidity and mortality in patients with advanced chronic kidney disease. These patients typically require oral phosphate binders to maintain phosphorus homeostasis, but the choice of which among several agents to use has been actively investigated and debated. Recent debate has been polarized between those who favor calcium-based binders for their proven efficacy and relatively low cost and those who favor sevelamer for its putative beneficial effects on inflammatory biomarkers and vascular calcification. This review summarizes the current state of the art of prescribing phosphate binders, ranging from large-scale clinical trials to focused mechanistic studies, and proposes that the available evidence does not conclusively prove the relative superiority of any one binder.

Hypertrophy and fibrosis in the cardiomyopathy of uremia--beyond coronary heart disease

Cardiac disease is the leading cause of death in uremic patients. In contrast to previous opinion, coronary events account for a relatively small proportion of cardiac deaths, the most common causes being sudden death and heart failure. Against this background the current text will discuss noncoronary cardiac pathology, specifically the pathogenesis and the morphological findings caused by (pathological) cardiac hypertrophy, cardiac interstitial fibrosis and microvascular disease.

Hyperphosphatemia of chronic kidney disease

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

Current Approaches in the Treatment of Chronic Kidney Disease Mineral and Bone Disorder

Patients with chronic kidney disease (CKD) develop mineral and bone disorder (MBD), a common and important complication, as a result of impaired phosphorus excretion and reduced vitamin D activation. Altered mineral metabolism is now recognized as an independent cardiovascular risk factor in end-stage renal disease patients and contributes to the risk for accelerating vascular calcification. CKD patients are at high risk for cardiovascular disease and vascular calcification which account for the high morbidity and mortality in this patient population. Pharmacotherapeutic interventions are necessary to manage and treat the condition. Multiple classes of agents including phosphorus binders, vitamin D analogs, and calcimimetics are now available to treat CKD-MBD. Recent data have shown that treatment with sevelamer and vitamin D analogs are associated with a reduction in calcification and cardiovascular mortality and improved survival. This article provides an overview of the strategies and considerations for the management of CKD-MBD, as well as their implications on clinical outcomes.

Phosphate Balance on Peritoneal Dialysis

Hyperphosphatemia is an independent predictor of mortality in end-stage renal disease patients, and 40% – 50% of peritoneal dialysis (PD) patients have suboptimal control of serum phosphate. Systematically addressing this problem requires an understanding of phosphate balance on PD. The present review discusses the determinants of daily phosphate load and focuses on the factors influencing renal and peritoneal clearance of phosphate.

Left ventricular hypertrophy: is hyperphosphatemia among dialysis patients a risk factor?

Cardiovascular disease occurs in ESRD patients at rates that are far higher than is seen in the general population, and cardiovascular deaths account for the majority of deaths among dialysis patients. Abnormal mineral metabolism is a novel cardiovascular risk factor among dialysis patients. Recently published results demonstrated that even with good control of BP and anemia, conventional hemodialysis is associated with significant left ventricular hypertrophy (LVH); however, daily hemodialysis was associated with a significant reduction in LV mass index (LVMI). Furthermore, it was shown that control of serum phosphorus correlates with the reduction in LVMI. These data suggest a novel mechanism for the deleterious effect of elevated serum phosphorus on cardiovascular outcomes among hemodialysis patients: LVH. Other investigators have noted an association of hyperphosphatemia and LVH; however, this study was the first to demonstrate that improvement in serum phosphorus is associated with reduction in LVM. In addition, it is shown that daily hemodialysis is an effective modality in improving serum phosphorus through significantly improved phosphorus removal. Elevated serum phosphorus leads to vascular calcification, which can lead to LVH by decreasing vascular compliance. However, our study showed an improvement in LVMI during a 12-mo period. Because vascular calcification is unlikely to remit over this time period, it is proposed that serum phosphorus has a reversible, cardiotoxic effect that leads to LVH that can be reversed successfully with good control of serum phosphorus.

PHOSPHORUS METABOLISM AND MANAGEMENT IN CHRONIC KIDNEY DISEASE: Renal Osteodystrophy, Phosphate Homeostasis, and Vascular Calcification

New advances in the pathogenesis of renal osteodystrophy (ROD) change the perspective from which many of its features and treatment are viewed. Calcium, phosphate, parathyroid hormone (PTH), and vitamin D have been shown to be important determinants of survival associated with kidney diseases. Now ROD dependent and independent of these factors is linked to survival more than just skeletal frailty. This review focuses on recent discoveries that renal injury impairs skeletal anabolism decreasing the osteoblast compartment of the skeleton and consequent bone formation. This discovery and the discovery that PTH regulates the hematopoietic stem cell niche alters our view of secondary hyperparathyroidism in chronic kidney disease (CKD) from that of a disease to that of a necessary adaptation to renal injury that goes awry. Furthermore, ROD is shown to be an underappreciated factor in the level of the serum phosphorus in CKD. The discovery and the elucidation of the mechanism of hyperphosphatemia as a cardiovascular risk in CKD change the view of ROD. It is now recognized as more than a skeletal disorder, it is an important component of the mortality of CKD that can be treated.

The Kidney Disease: Improving Global Outcomes website: Comparison of guidelines as a tool for harmonization

Chronic kidney disease (CKD) is a worldwide public health problem with significant comorbidity and mortality. Improving quality of life and survival of CKD patients necessitates a large number of preventive and therapeutic interventions. To resolve these issues several organizations have developed guidelines, which are difficult to compare comprehensively. The Kidney Disease: Improving Global Outcomes website at http://kdigo.org compares five major guidelines. The section 'compare guidelines' covers 41 topics distributed over five major subjects: (1) general clinics; (2) hemodialysis (HD); (3) vascular access for HD; (4) peritoneal dialysis; and (5) chemistries. The tables compare guideline recommendations and the evidence levels on which they are based, with direct links to each of the guidelines. These data show that the different guideline groups tend to propose similar targets, but that nuances in the guideline statements, their rationale, and grading of evidence levels present some discrepancies, although most guidelines are based on the same literature. We conclude that there is an urgent need to harmonize existing guidelines, and for a global initiative to avoid the parallel development of conflicting guidelines on the same topics. The tables displayed on the website offer a basis for structuring this process, a procedure which has recently been initiated by a body composed of the five guideline development groups.

Blood pressure control in pediatric hemodialysis: the Midwest Pediatric Nephrology Consortium Study

Hypertension is frequent in pediatric patients receiving dialysis, with an especially high rate reported in children on hemodialysis (HD). We performed the present study to assess blood pressure (BP) status and identify risk factors for poor BP control in children on maintenance HD. One month's dialysis records were collected from 71 subjects receiving HD in ten dialysis units participating in the Midwest Pediatric Nephrology Consortium (MWPNC). For each HD session, data on pre- and posttreatment weights and BPs were recorded. Hypertension, defined as mean BP >or= 95th percentile, was found in 42 (59%) subjects. Eleven subjects (15.5%) had prehypertension, defined as mean BP between the 90th and 95th percentiles, while 18 subjects (25.3%) had normal BP (<90th percentile). BP significantly decreased at the end of a dialysis session; however, only 15 of 42 hypertensive subjects (35%) normalized their BP. Hypertensive subjects were younger (p = 0.03), had higher serum phosphorus (p = 0.01), and had more elevated posttreatment weight above estimated dry weight (p = 0.02). Logistic regression showed that younger age (p = 0.02) and higher serum phosphorus (p = 0.02) independently predicted hypertensive status. In conclusion, this study emphasizes the difficulty of BP control in pediatric HD patients. Especially poor BP control was found in younger children; those patients who do not reach their posttreatment weight goals, perhaps reflecting their hypervolemic state; and those who have higher serum phosphorus levels.

Emerging strategies for lowering serum phosphorous in patients with end-stage renal disease

Hyperphosphataemia is a major problem in patients with chronic kidney disease as it has been associated with increased morbidity and mortality. Over the last four decades, different modalities have been applied to treat hyperphosphataemia with varying degrees of success. Unfortunately, treatment strategies have led to unforeseen complications. These have prompted the development of new classes of medications with potentially better efficacy and few short-term and long-term side effects. This article reviews the causes, mechanism and management of hyperphosphataemia.

Vascular calcification and renal osteodystrophy relationship in chronic kidney disease

Cardiovascular disease and stroke account for 60-70% of all deaths in patients with end-stage renal disease (ESRD), at a risk that is 10-20-fold the age- and sex-matched general population. There is also increased coronary artery calcification and increased cardiovascular mortality in chronic kidney disease (CKD) and dialysis patients compared with the general population. Bone is similarly abnormal in CKD. There is an increased incidence of low bone mass and fractures in dialysis patients compared with the general population. Furthermore, a hip fracture in a dialysis patient is associated with a doubling of the mortality observed in nondialysis patients with a hip fracture. These two problems may be linked, as cross-sectional studies have demonstrated an inverse relationship between osteoporosis and coronary artery calcification in the general population and in ESRD patients. In vitro and ex vivo, there is clear evidence that vascular calcification is an active cell-mediated process, made worse by disorders of mineral metabolism. Many factors known to be associated with cardiovascular disease in CKD patients can directly increase calcification in vitro. In addition, in CKD, there are many mechanisms by which bone may adversely affect vascular calcification including disorders of bone remodelling, altered secretion of parathyroid hormone (PTH), hyperphosphatemia, hypercalcaemia, use of calcium based binders, and excessive vitamin D therapy. The coexistence of vascular risk factors and abnormal bone represent a double threat to the well being of patients with CKD.

The Case against Calcium-Based Phosphate Binders

Disturbances of mineral metabolism are associated with significant morbidity and mortality in patients with chronic kidney disease. Unfortunately, some of the treatments for these disturbances also have been found to be associated with morbidity. More recently, there is increasing evidence in the form of prospective, randomized trials that the use of calcium-based phosphate binders contributes to progressive coronary artery and aorta calcification compared with the non-calcium-containing binder sevelamer. Moreover, there is compelling biologic plausibility that hyperphosphatemia and excess exogenous calcium administration can accelerate vascular calcification. Unfortunately, there is no bedside test that can determine whether there is a dose of calcium salts (either as maintenance or as cumulative dose) that can be administered safely, and, unfortunately, the serum calcium concentration does not reflect calcium balance. Therefore, calcium-based phosphate binders should be avoided in many, if not most, patients who are undergoing dialysis.

New insights into mineral and skeletal regulation by active forms of vitamin D

Recent studies in mice using genetic approaches have shed new light on the physiological effects of 1,25-dihydroxyvitamin D (1,25(OH)(2)D) and the vitamin D receptor (VDR) in skeletal and mineral homeostasis, and on their interaction with calcium. These studies in mice with targeted deletion of the 25-hydroxyvitamin D-1alpha-hydroxylase (1alpha(OH)ase), and of the VDR or of double mutants, have shown the discrete effects of calcium in inhibiting parathyroid hormone secretion and in enhancing bone mineralization, but overlapping effects of calcium and 1,25(OH)(2)D on inhibiting parathyroid growth and on normal development of the cartilaginous growth plate. The 1,25(OH)(2)D/VDR system is essential, however, in enhancing intestinal calcium absorption and in optimally increasing osteoclastic activation. In addition, the 1,25(OH)(2)D/VDR system has important anabolic effects on bone, thus defining a dual role for this system in bone turnover. These studies are revealing functions of the vitamin D/VDR system which have relevance for new concepts of the pathophysiology of renal bone disease and, in particular, of the adynamic bone disorder, and for the development of new analogs of the active form of vitamin D, which have less calcemic activity and greater skeletal anabolic effects.

Association of mineral metabolism with an increase in cellular adhesion molecules: another link to cardiovascular risk in maintenance haemodialysis?

BACKGROUND

Abnormal mineral metabolism is associated with increased cardiovascular morbidity and mortality. The exact pathogenesis linking mineral metabolism to cardiovascular risk is unknown. This study was undertaken to investigate the association between serum phosphate and/or Ca x PO(4) product with serum levels of soluble E-selectin (sE-selectin), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 and the degree of carotid artery atherosclerosis in patients on haemodialysis.

METHODS

Seventy-three patients (46 male, 27 female; mean age 48+/-13 years, on haemodialysis for 82+/-80 months) were included in the study. All patients were stable, had no evidence of vascular disease and/or active infection. Consecutive 6 months clinical and laboratory data were obtained for each patient from their medical records and mean values were used for analysis. Serum levels of soluble adhesion molecules were assayed by ELISA. All subjects underwent a detailed evaluation of the carotid arteries.

RESULTS

The percentage of patients who met all three targets of NKF-K/DOQI for phosphate, calcium and Ca x PO(4) product was 27.1%, whereas those who did not achieve the target in one, two or three parameters was 28.1, 17.7 and 14.6%, respectively. The sICAM-1 levels were significantly higher in patients who had hyperphosphataemia (serum phosphate >5.5 mg/dl; P = 0.044) and hypercalcaemia (serum calcium >9.5 mg/dl; P = 0.014), both sE-selectin and sICAM-1 levels were significantly higher in patients with Ca x PO(4) product levels above 55 mg(2)/dl(2) (P = 0.002 and P = 0.000, respectively). Soluble E-selectin and sICAM levels demonstrated a near-linear increase in parallel to the degree of deviation from mineral metabolism targets. Soluble E-selectin and sICAM levels were correlated with serum phosphate and Ca x PO(4) product, but there were no correlations between adhesion molecules and carotid measurements.

CONCLUSION

These findings suggest that in stable haemodialysis patients abnormal bone mineral metabolism was associated with increased soluble adhesion molecules. These alterations in adhesion molecules may favour the development of cardiovascular changes and contribute to high cardiovascular morbidity and mortality in patients with abnormal mineral metabolism.

Comparison of surgically removed cardiac valves of patients with ESRD with those of the general population

BACKGROUND

Patients with end-stage renal disease (ESRD) have increased vascular and valvular calcification compared with the general population. Recently, 44% of renal transplant recipients were found to have vascular calcification of the medial layer of the inferior epigastric artery that was associated with deposition of bone matrix proteins. Similar findings have been reported for native and bioprosthetic cardiac valves surgically removed from patients without ESRD.

METHODS

To determine whether valvular calcification in patients with ESRD is similar to that in patients without ESRD, we retrospectively examined surgically excised native cardiac valves of all hemodialysis patients and compared them pathologically with those of matched controls without renal failure. Valves were examined by using routine stains and immunohistochemistry for markers to endothelial cells, macrophages, B and T lymphocytes, alkaline phosphatase, osteopontin, and bone morphogenic protein 4.

RESULTS

Histologically, 7 of 10 valves from patients with ESRD had moderate to severe inflammation compared with 1 of 10 valves from control patients. Patients with ESRD had more endothelial cells/vascularity (P = 0.002) and macrophages (P = 0.069). There was no difference between the 2 groups with respect to B and T lymphocytes, alkaline phosphatase, osteopontin, or bone morphogenic protein 4.

CONCLUSION

The noncollagenous proteins bone morphogenic protein and osteopontin have been shown in surgically removed cardiac valves of patients with ESRD and the general population. However, valvular calcification in patients with ESRD is associated with enhanced inflammation, consistent with the previously reported greater C-reactive protein levels in this patient population and their increased risk for death.

Consequences of hyperphosphatemia in patients with end-stage renal disease (ESRD)

Hyperphosphatemia is invariably present among patients with end-stage renal disease (ESRD) and is becoming an increasingly important clinical entity. Despite concerted efforts by patients, dietitians, and nephrologists to control serum phosphorus, a recent study by Block et al found that more than 60% of patients on hemodialysis in the United States have serum phosphorus levels above the recommended goal of 5.5 mg/dL. Historically, nephrologists have been concerned about the central role of elevated serum phosphorus in the pathogenesis of secondary hyperparathyroidism and extraosseous calcification. However, the consequences of untreated hyperphosphatemia have assumed more importance in the last few years, largely due to recent clinical studies that revealed a more sinister role of elevated serum phosphorus in increasing the mortality risk among patients with ESRD. Hemodialysis patients with serum phosphorus greater than 6.5 mg/dL were reported to have a 27% higher mortality risk than patients with serum phosphorus between 2.4 and 6.5 mg/dL. The pathophysiologic mechanisms by which persistent hyperphosphatemia enhances the mortality risk in dialysis patients are not yet completely understood. However, given that inadequate control of serum phosphorus contributes to elevated calcium-phosphorus product (Ca x P), untreated hyperphosphatemia may play a key role in cardiovascular calcification. In response to these findings, the National Kidney Foundation Kidney Disease Outcome Quality Initiative (K/DOQI) Clinical Practice Guidelines for Bone Metabolism and Disease in Chronic Kidney Disease have recently recommended more stringent levels for controlling serum phosphorus and Ca x P product in order to improve patients' quality of life and longevity.