Phosphate and cardiovascular disease

Phosphorus balance calculator: an individualized tool for treatment of hyperphosphatemia in hemodialysis patients

BACKGROUND

Lack of evaluations of the dietary phosphorus and dialysis phosphorus removal in daily clinical practice are common obstacles to assessing phosphorus balance and controlling phosphorus in hemodialysis patients. We aimed to investigate whether individualized therapy using a phosphorus balance calculator improves phosphorus control.

METHODS

A randomized, open-label, multicenter, 4-week clinical trial was conducted. A total of 119 maintenance hemodialysis patients aged 18-85 years old and with serum phosphorus level >1.45 mmol/L from three university teaching hospitals in Shanghai were enrolled. Patients were randomized in a 1:1 ratio to individualized therapy (n = 60) or conventional therapy (n = 59). The primary outcome was the serum phosphorus concentration after 4-week treatment. Secondary outcomes included the serum calcium and parathyroid hormone (PTH) concentrations, changes in serum phosphorus, calcium and PTH concentrations, and the proportion of patients achieving target ranges of serum phosphorus, calcium and PTH after 4-week treatment.

RESULTS

Among 119 randomized participants [mean age 62 years; 68 male (57%)], 116 completed the trial. Using the phosphorus balance calculator, the individualized group achieved a better phosphorus balance state and significantly reduced serum phosphorus (1.62 ± 0.45 mmol/L versus 1.85 ± 0.45 mmol/L, P = .006), increased the proportions of patients achieving target serum phosphorus range (41% versus 18%, P = .006) and had greater adjusted mean difference in change in serum phosphorus over the 4 weeks (-0.47 versus -0.23 mmol/L, P = .010) when compared with conventional therapy. No significant changes were observed in serum calcium and PTH levels, the proportion of patients achieving target serum calcium or PTH levels, or the adjusted mean difference of serum calcium and PTH levels over the treatment period.

CONCLUSION

Phosphorus balance calculator was proved to improve serum phosphorus control in patients undergoing maintenance hemodialysis, offering a new tool for managing hyperphosphatemia.

Effect of partial substitution of complex phosphates with sodium bicarbonate on aggregation, conformation and gel properties of beef-pork-chicken complex myofibrillar proteins

BACKGROUND

Complex phosphates (CP) can improve the physicochemical properties and gelation properties of myofibrillar fibrous protein (MP) in mixed meat products, but an excessive intake of phosphates over a long period of time is harmful to health. The present study investigated the effects of partial or complete substitution of CP with sodium bicarbonate (SB) on the physicochemical properties and gel properties of beef-pork-chicken mixed myofibrillar protein (BPC-MP), aiming to evaluate the feasibility of this method in reducing the amount of phosphate in mixed meat products.

RESULTS

Under the optimal substitution conditions, the turbidity of BPC-MP was reduced by 37.8%, the net negative potential was increased by 28.9% and the modulus of elasticity (G') was increased. The tertiary structure indexes of protein (including fluorescence intensity, surface hydrophobicity and active thiol content) were significantly changed, whereas the α-helix and β-turn angle contents in the secondary structure of protein were significantly increased. In addition, the water retention ability and strength of gel were also improved, which were increased by 20.7% and 42.6%, respectively. The results of scanning electron microscopy showed that the SB substitution group had a more compact and ordered microstructure.

CONCLUSION

The results showed that partial substitution of CP with SB reduced the amount of phosphate added to BPC-MP and had a positive effect on the physicochemical and gel properties of BPC-MP. © 2024 Society of Chemical Industry.

Mechanical stretch leads to increased caveolin-1 content and mineralization potential in extracellular vesicles from vascular smooth muscle cells

BACKGROUND

Hypertension-induced mechanical stress on vascular smooth muscle cells (VSMCs) is a known risk factor for vascular remodeling, including vascular calcification. Caveolin-1 (Cav-1), an integral structural component of plasma membrane invaginations, is a mechanosensitive protein that is required for the formation of calcifying extracellular vesicles (EVs). However, the role of mechanics in Cav-1-induced EV formation from VSMCs has not been reported.

RESULTS

Exposure of VSMCs to 10% mechanical stretch (0.5 Hz) for 72 h resulted in Cav-1 translocation into non-caveolar regions of the plasma membrane and subsequent redistribution of Cav-1 from the VSMCs into EVs. Inhibition of Rho-A kinase (ROCK) in mechanically-stimulated VSMCs exacerbated the liberation of Cav-1 positive EVs from the cells, suggesting a potential involvement of actin stress fibers in this process. The mineralization potential of EVs was measured by incubating the EVs in a high phosphate solution and measuring light scattered by the minerals at 340 nm. EVs released from stretched VSMCs showed higher mineralization potential than the EVs released from non-stretched VSMCs. Culturing VSMCs in pro-calcific media and exposure to mechanical stretch increased tissue non-specific alkaline phosphatase (ALP), an important enzyme in vascular calcification, activity in EVs released from the cells, with cyclic stretch further elevating EV ALP activity compared to non-stretched cells.

CONCLUSION

Our data demonstrate that mechanical stretch alters Cav-1 trafficking and EV release, and the released EVs have elevated mineralization potential.

Estimated Intake of Potassium, Phosphorus and Zinc with the Daily Diet Negatively Correlates with ADP-Dependent Whole Blood Platelet Aggregation in Older Subjects

The aggregation of blood platelets is the pivotal step that leads to thrombosis. The risk of thrombotic events increases with age. Available data suggest that minerals taken with diet can affect the course of thrombosis. However, little is known about the relationship between platelet aggregability and mineral intake with diet among elderly people. Thus, we evaluated the associations between the reactivities of platelets to arachidonic acid, collagen or ADP and the estimated quantities of minerals consumed as a part of the daily diet in 246 subjects aged 60-65 years (124 men and 122 women). The found simple (not-adjusted) Spearman's rank negative correlations are as follows: 1. arachidonate-dependent aggregation and the amounts of potassium, zinc, magnesium, phosphorus, iron, copper and manganese; 2. collagen-dependent aggregation and the amounts of potassium, phosphorus, iron and zinc; and 3. ADP-dependent aggregation and the amounts of potassium, phosphorus and zinc. The negative associations between ADP-dependent platelet reactivity and the amount of potassium, phosphorus and zinc and between collagen-dependent aggregability and the amount of phosphorus were also noted after adjusting for a bunch of cardiovascular risk factors. Overall, in older subjects, the intake of minerals with diet is negatively related to blood platelet reactivity, especially in response to ADP. Diet fortification with some minerals may possibly reduce the thrombotic risk among elderly patients.

Fe(III) cross-linked cellulose-agar hydrogel beads for efficient phosphate removal from aqueous solutions

Fe(III) cross-linked cellulose agar beads (Fe-CLCAB) were synthesized by sol-gel method and employed as adsorbents for the removal of phosphate ions from aqueous medium. The synthesized Fe-CLCAB was characterized by its swelling property, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and UV-Vis absorption spectroscopic analysis. Batch adsorption studies were carried out to find out the optimum conditions of phosphate uptake. The adsorption process was found to fit both Langmuir and Freundlich adsorption isotherm model, pseudo-second-order kinetic model, and Elovich kinetic model. Ninety-four percent phosphate adsorption was achieved with 500 beads at pH 5. Maximum monolayer adsorption capacity was 73.13 mg/g. A two-step elution process using sodium chloride solution was suitable for complete desorption of phosphate from Fe-CLCAB. Six cyclic adsorption-desorption tests were conducted using a 0.1 M NaCl solution as desorbing agent. The removal efficiency of regenerated Fe-CLCAB was 42% of its original value after six cycles, which validates good stability and effectiveness of the prepared hydrogel beads. Ion exchange plays a vital role during adsorption/desorption of phosphate.

The Role of Plant-Based Diets in Preventing and Mitigating Chronic Kidney Disease: More Light than Shadows

Chronic kidney disease (CKD) is a non-communicable disease that affects >10% of the general population worldwide; the number of patients affected by CKD is increasing due in part to the rise in risk factors such as obesity, hypertension, and diabetes mellitus. As many studies show, diet can be an important tool for preventing and mitigating the onset of non-communicable diseases. Plant-based diets (PBDs) are those that emphasize the consumption of plant foods and may or may not include small or moderate amounts of animal foods. Recently, these diets have received increasing interest because they have been associated with favourable effects on health and also appear to protect against the development and progression of CKD. PBDs, which are associated with protein restrictions, seem to offer adjunctive advantages in patients with chronic kidney disease, as compared to conventional low-protein diets that include animal proteins. The principal aims of this review are to provide a comprehensive overview of the existing literature regarding the role of plant-based diets and low-protein, plant-based diets in the context of chronic kidney disease. Moreover, we try to clarify the definition of plant-based diets, and then we analyse possible concerns about the use of PBDs in patients with chronic kidney disease (nutritional deficiency and hyperkalaemia risk). Finally, we offer some strategies to increase the nutritional value of plant-based low-protein diets. In the Materials and Methods section, many studies about plant-based diets and low-protein plant-based diets (e.g., the very-low-protein diet and vegan low-protein diet, LPD) in chronic kidney disease were considered. In the Results and Conclusion section, current data, most from observational studies, agree upon the protective effect of plant-based diets on kidney function. Moreover, in patients with advanced CKD, low-protein plant-based options, especially a very-low-protein diet supplemented with heteroanalogues (VLPDs), compared to a conventional LPD appear to offer adjunctive advances in terms of delaying dialysis and mitigating metabolic disturbances. However, further studies are necessary to better investigate the possible metabolic and cardiovascular advantages of plant-based LPDs versus conventional LPDs.

Machine learning algorithms to predict major adverse cardiovascular events in patients with diabetes

BACKGROUND

Major Adverse Cardiovascular Events (MACE) are common complications of type 2 diabetes mellitus (T2DM) that include myocardial infarction (MI), stroke, and heart failure (HF). The objective of the current study was to predict MACE among T2DM patients.

METHODS

Type 2 diabetes mellitus patients above 18 years old were recruited for the study from the All of Us Research Program. Eligible participants were those who took sodium-glucose cotransporter 2 inhibitors. Different Machine learning algorithms: including RandomForest (RF), XGBoost, logistic regression (LR), and weighted ensemble model (WEM) were employed. Clinical attributes, electrolytes and biomarkers were explored in predicting MACE. The feature importance was determined using mean decrease accuracy.

RESULTS

Overall, 9, 059 subjects were included in the analyses, of which 5197 (57.4%) were females. The XGBoost Model demonstrated a prediction accuracy of 0.80 [0.78-0.82], which is higher as compared to the RF 0.78[0.76-0.80], the LR model 0.65 [0.62-0.67], and the WEM 0.75 [0.73-0.76], respectively. The classification accuracy of the models for stroke was more than 95%, which was higher than prediction accuracy for MI (∼85%), and HF (∼80%). Phosphate, blood urea nitrogen and troponin levels were the major predictors of MACE.

CONCLUSION

The ML models had shown acceptable performance in predicting MACE in T2DM patients, except the LR model. Phosphate, blood urea nitrogen, and other electrolytes were important predictors of MACE, which is consistent between the individual components of MACE, such as stroke, MI, and HF. These parameters can be calibrated as prognostic parameters of MACE events in T2DM patients.

Phosphorus May Induce Phenotypic Transdifferentiation of Vascular Smooth Muscle Cells through the Reduction of microRNA-145

Phosphorus is a vital element for life found in most foods as a natural component, but it is also one of the most used preservatives added during food processing. High serum phosphorus contributes to develop vascular calcification in chronic kidney disease; however, it is not clear its effect in a population without kidney damage. The objective of this in vivo and in vitro study was to investigate the effect of high phosphorus exposure on the aortic and serum levels of miR-145 and its effect on vascular smooth muscle cell (VSMCs) changes towards less contractile phenotypes. The study was performed in aortas and serum from rats fed standard and high-phosphorus diets, and in VSMCs exposed to different concentrations of phosphorus. In addition, miR-145 silencing and overexpression experiments were carried out. In vivo results showed that in rats with normal renal function fed a high P diet, a significant increase in serum phosphorus was observed which was associated to a significant decrease in the aortic α-actin expression which paralleled the decrease in aortic and serum miR-145 levels, with no changes in the osteogenic markers. In vitro results using VSMCs corroborated the in vivo findings. High phosphorus first reduced miR-145, and afterwards α-actin expression. The miR-145 overexpression significantly increased α-actin expression and partially prevented the increase in calcium content. These results suggest that miR-145 could be an early biomarker of vascular calcification, which could give information about the initiation of the transdifferentiation process in VSMCs.

Biochemical spectrum of parathyroid hormone disorders in patients attending Tribhuvan University Teaching Hospital, Kathmandu, Nepal

Objectives

This study intends to determine the association of parathormone with vitamin D and other biochemical parameters (calcium and phosphate) and evaluate the relationship between low vitamin D and parathormone levels.

Methods

A hospital-based cross-sectional study was conducted among 310 study participants over the period of 1 year. Patients who underwent laboratory investigations for vitamin D, parathormone, calcium, and phosphate in the Clinical Biochemistry Laboratory at the Institute of Medicine, Tribhuvan University Teaching Hospital were included. Serum intact parathyroid hormone, vitamin D, calcium, and phosphate were measured in Abbott Architect (ci4100) integrated system autoanalyzer.

Results

Among the 310 study participants, 177 (57%) were males and 43% were females. The mean age of the patient was 47.09 ± 19.01 years. High intact parathyroid hormone (>68 pg/ml) was observed in 73% of the patients. Low vitamin D (<20 ng/ml) was present in 30.2% of the patients. The findings from our study depict that there is a negative significant correlation between intact parathyroid hormone levels, vitamin D, and calcium levels and a positive correlation between intact parathyroid hormone and phosphate levels (p < 0.001).

Conclusions

The findings from our study illustrate that there is a swapping drift in the profile of hyperparathyroidism in the Nepalese population. We report the presence of hyperparathyroidism in the middle age group than in the older age group contradictory to that reported in the literature.

Plasma metallomics reveals potential biomarkers and insights into the ambivalent associations of elements with acute myocardial infarction

Acute myocardial infarction (AMI) is a leading cause of mortality and morbidity worldwide. Using a validated and efficient ICP-MS/MS-based workflow, a total of 30 metallomic features were profiled in a study comprising 101 AMI patients and 66 age-matched healthy controls. The metallomic features include 12 essential elements (Ca, Co, Cu, Fe, K, Mg, Mn, Na, P, S, Se, Zn), 8 non-essential/toxic elements (Al, As, Ba, Cd, Cr, Ni, Rb, Sr, U, V), and 10 clinically relevant element-pair product/ratios (Ca/Mg, Ca×P, Cu/Se, Cu/Zn, Fe/Cu, P/Mg, Na/K, Zn/Se). Preliminary linear regression with feature selection confirmed smoking status as a predominant determinant for the non-essential/toxic elements, and revealed potential routes of action. Univariate assessments with adjustments for covariates revealed insights into the ambivalent relationships of Cu, Fe, and P with AMI, while also confirming cardioprotective associations of Se. Also, beyond their roles as risk factors, Cu and Se may be involved in the response mechanism in AMI onset/intervention, as demonstrated via longitudinal data analysis with 2 additional time-points (1-/6-month follow-up). Finally, based on both univariate tests and multivariate classification modelling, potentially more sensitive markers measured as element-pair ratios were identified (e.g., Cu/Se, Fe/Cu). Overall, metallomics-based biomarkers may have utility for AMI prediction.

Serum Proteomic Profiles Reflect the Stages of Myxomatous Mitral Valve Disease in Dogs

Canine myxomatous mitral valve disease (MMVD) is similar to Barlow's form of MMVD in humans. These valvulopathies are complex, with varying speeds of progression. We hypothesized that the relative abundances of serum proteins would help identify the consecutive MMVD stages and discover new disease pathways on a systemic level. To identify distinction-contributing protein panels for disease onset and progression, we compared the proteomic profiles of serum from healthy dogs and dogs with different stages of naturally occurring MMVD. Dogs were divided into experimental groups on the basis of the left-atrium-to-aorta ratio and normalized left ventricular internal dimension in diastole values. Serum was collected from healthy (N = 12) dogs, dogs diagnosed with MMVD in stages B1 (N = 13) and B2 (N = 12) (asymptomatic), and dogs diagnosed with MMVD in chronic stage C (N = 13) (symptomatic). Serum biochemistry and selected ELISAs (galectin-3, suppression of tumorigenicity, and asymmetric dimethylarginine) were performed. Liquid chromatography-mass spectrometry (LC-MS), tandem mass tag (TMT) quantitative proteomics, and statistical and bioinformatics analysis were employed. Most of the 21 serum proteins with significantly different abundances between experimental groups (p < 0.05, FDR ˂ 0.05) were classified as matrix metalloproteinases, protease inhibitors, scaffold/adaptor proteins, complement components, anticoagulants, cytokine, and chaperone. LC-MS TMT proteomics results obtained for haptoglobin, clusterin, and peptidase D were further validated analytically. Canine MMVD stages, including, for the first time, asymptomatic B1 and B2 stages, were successfully distinguished in dogs with the disease and healthy dogs on the basis of the relative abundances of a panel of specific serum proteins. Most proteins with significantly different abundances were involved in immune and inflammatory pathways. Their role in structural remodeling and progression of canine MMVD must be further investigated. Further research is needed to confirm the resemblance/difference with human MMVD. Proteomics data are available via ProteomeXchange with the unique dataset identifier PXD038475.

Effects of oral alkali drug therapy on clinical outcomes in pre-dialysis chronic kidney disease patients: a systematic review and meta-analysis

BACKGROUND

Metabolic acidosis accelerates the progression of chronic kidney disease (CKD) and increases the mortality rate. Whether oral alkali drug therapy benefits pre-dialysis CKD patients is controversial. We performed a meta-analysis of the effects of oral alkali drug therapy on major clinical outcomes in pre-dialysis CKD patients.

METHODS

We systematically searched MEDLINE using the Ovid, EMBASE, and Cochrane Library databases without language restriction. We included all eligible clinical studies that involved pre-dialysis CKD adults and compared those who received oral alkali drug therapy with controls.

RESULTS

A total of 18 eligible studies, including 14 randomized controlled trials and 4 cohort studies reported in 19 publications with 3695 participants, were included. Oral alkali drug therapy led to a 55% reduction in renal failure events (relative risk [RR]: 0.45; 95% confidence interval [CI]: 0.25-0.82), a rate of decline in the estimated glomerular filtration rate (eGFR) of 2.59 mL/min/1.73 m² per year (95% CI, 0.88-4.31). There was no significant effect on decline in eGFR events (RR: 0.34; 95% CI: 0.09-1.23), proteinuria (standardized mean difference: -0.32; 95% CI: -1.08 to 0.43), all-cause mortality events (RR: 0.90; 95% CI: 0.40-2.02) and cardiovascular (CV) events (RR: 1.03; 95% CI: 0.32-3.37) compared with the control groups.

CONCLUSION

Based on the available and low-to-moderate certainty evidence, oral alkali drug therapy might potentially reduce the risk of kidney failure events, but no benefit in reducing all-cause mortality events, CV events, decline in eGFR and porteninuria.

Diesel particulate matter exposure deteriorates cardiovascular health and increases the sensitivity of rat heart towards ischemia reperfusion injury via suppressing mitochondrial bioenergetics function

Documents from previous studies do not sufficiently explain the pathophysiological alterations involved in rat hearts exposed to PM2.5 from diesel exhaust, termed as Diesel Particulate matter (DPM). In the present study, we explored the cardiovascular effect of DPM exposure on the recovery of heart from Ischemia reperfusion injury (IR) and explored the probable cause-effect relationship. Two groups of female Wistar rats were exposed to 0.5 mg/ml DPM for 1 h and 3 h durations daily for 21 days via a whole-body exposure system. At the end of 21st day, the animals were sacrificed and the heart was subjected to IR via Langendorff isolated rat heart perfusion system. 21 days of exposure altered cardiac electrophysiology and the ultra-structure of myocardium. Also, the same group of animals exhibited calcification in the vasculature. These changes were prominent in animals exposed to DPM for 3 h daily. Administration of DPM to H9C2 cells resulted in 15% and 36% cell death after 1hr and 3hrs of incubation, respectively. When the hearts were challenged to IR, both 1 h and 3 h exposed hearts exhibited a significant decline in IR recovery. At the sub-cellular level, DPM exposure reduced ATP levels, mitochondrial copy number, and increased oxidative stress after IR in both exposure groups. These changes were markedly seen in the interfibrillar mitochondrial fraction of the mitochondria. Hence, we conclude that exposure to PM2.5 from diesel exhaust alters electrophysiology and ultrastructure of heart and reduces the level of cellular mediators, thereby compromising the ability of heart to withstand IR injury.

Benefit of continued noninvasive cardiac monitoring in geriatric trauma: A retrospective review of geriatric pelvis, hip, and femur fractures and analysis of cardiac events during immediate post-traumatic course

Objective

The geriatric population suffers from a predisposition to cardiac events due to physiologic changes commonly associated with aging. The majority of the trauma population seen at our facility is within the geriatric population (greater than 65 years old). Therefore, this study was aimed to determine which of those preexisting factors were associated with an increased risk for developing cardiac event. By assessing those risks, we hoped to determine a timeline for the highest risk of cardiac event occurrence, in order to identify a safe period of when cardiac monitoring was indicated.

Methods

A retrospective study performed over 6 months reviewing geriatric trauma patients with hip, pelvis, or femur fractures, n = 125. A list of predetermined risk factors including comorbidities, pathologies, laboratory values, electrocardiogram findings, and surgery was crossed with the patient's records in order to identify factors for increased risk of cardiac event. Once patients who had documented cardiac events were identified, a temporal pattern of cardiac event occurrence was analyzed in order to determine a period when noninvasive cardiac monitoring should remain in place.

Results

In 125 patients, 40 cardiac events occurred in 30 patients. The analyzed variables with statistically significant associations for having a cardiac event were comorbidities (p = 0.019), elevated body mass index (p = 0.001), abnormal initial phosphorus (p = 0.002), and an electrocardiogram finding of other than normal sinus rhythm (p = 0.020). Of the identified cardiac events, we found that by hospital day 3 68% of cardiac event had occurred, with 85% by hospital day 4, 95% by day 5, and 100% within the first 7 days of admission.

Conclusion

Patient history of cardiac comorbidities, elevated body mass index, abnormal phosphorus, and abnormal electrocardiogram findings were found to be significant risk factors for cardiac event development in geriatric trauma. All recorded events in our study occurred within 7 days of the initial trauma.

A phosphate and calcium-enriched diet promotes progression of 5/6-nephrectomy-induced chronic kidney disease in C57BL/6 mice

C57BL/6 mice are known to be rather resistant to the induction of experimental chronic kidney disease (CKD) by 5/6-nephrectomy (5/6-Nx). Here, we sought to characterize the development of CKD and its cardiac and skeletal sequelae during the first three months after 5/6-Nx in C57BL/6 mice fed a calcium- and phosphate enriched diet (CPD) with a balanced calcium/phosphate ratio. 5/6-NX mice on CPD showed increased renal fibrosis and a more pronounced decrease in glomerular filtration rate when compared to 5/6-Nx mice on normal diet (ND). Interestingly, despite comparable levels of serum calcium, phosphate, and parathyroid hormone (PTH), circulating intact fibroblast growth factor-23 (FGF23) was 5 times higher in 5/6-Nx mice on CPD, relative to 5/6-Nx mice on ND. A time course experiment revealed that 5/6-Nx mice on CPD developed progressive renal functional decline, renal fibrosis, cortical bone loss, impaired bone mineralization as well as hypertension, but not left ventricular hypertrophy. Collectively, our data show that the resistance of C57BL/6 mice to 5/6-Nx can be partially overcome by feeding the CPD, and that the CPD induces a profound, PTH-independent increase in FGF23 in 5/6-Nx mice, making it an interesting tool to assess the pathophysiological significance of FGF23 in CKD.

Skeletal myopathy in CKD: a comparison of adenine-induced nephropathy and 5/6 nephrectomy models in mice

Preclinical animal models of chronic kidney disease (CKD) are critical to investigate the underlying mechanisms of disease and to evaluate the efficacy of novel therapeutics aimed to treat CKD-associated pathologies. The objective of the present study was to compare the adenine diet and 5/6 nephrectomy (Nx) CKD models in mice. Male and female 10-wk-old C57BL/6J mice (n = 5-9 mice/sex/group) were randomly allocated to CKD groups (0.2-0.15% adenine-supplemented diet or 5/6 Nx surgery) or the corresponding control groups (casein diet or sham surgery). Following the induction of CKD, the glomerular filtration rate was reduced to a similar level in both adenine and 5/6 Nx mice (adenine diet-fed male mice: 81.1 ± 41.9 µL/min vs. 5/6 Nx male mice: 160 ± 80.9 µL/min, P = 0.5875; adenine diet-fed female mice: 112.9 ± 32.4 µL/min vs. 5/6 Nx female mice: 107.0 ± 45.7 µL/min, P = 0.9995). Serum metabolomics analysis indicated that established uremic toxins were robustly elevated in both CKD models, although some differences were observed between CKD models (i.e., p-cresol sulfate). Dysregulated phosphate homeostasis was observed in the adenine model only, whereas Ca2+ homeostasis was disturbed in male mice with both CKD models. Compared with control mice, muscle mass and myofiber cross-sectional areas of the extensor digitorum longus and soleus muscles were ∼18-24% smaller in male CKD mice regardless of the model but were not different in female CKD mice (P > 0.05). Skeletal muscle mitochondrial respiratory function was significantly decreased (19-24%) in CKD mice in both models and sexes. These findings demonstrate that adenine diet and 5/6 Nx models of CKD have similar levels of renal dysfunction and skeletal myopathy. However, the adenine diet model demonstrated superior performance with regard to mortality (∼20-50% mortality for 5/6 Nx vs. 0% mortality for the adenine diet, P < 0.05 for both sexes) compared with the 5/6 Nx surgical model.NEW & NOTEWORTHY Numerous preclinical models of chronic kidney disease have been used to evaluate skeletal muscle pathology; however, direct comparisons of popular models are not available. In this study, we compared adenine-induced nephropathy and 5/6 nephrectomy models. Both models produced equivalent levels of muscle atrophy and mitochondrial impairment, but the adenine model exhibited lower mortality rates, higher consistency in uremic toxin levels, and dysregulated phosphate homeostasis compared with the 5/6 nephrectomy model.

Phosphate Control: The Next Frontier in Dialysis Cardiovascular Mortality

BACKGROUND

Cardiovascular disease (CVD) is a major cause of death in patients with chronic kidney disease (CKD) on dialysis. Mortality rates are still unacceptably high even though they have fallen in the past 2 decades. Hyperphosphatemia (elevated serum phosphate levels) is seen in almost all patients with advanced CKD and is by far the largest remaining modifiable contributor to CKD mortality.

SUMMARY

Phosphate retention drives multiple physiological mechanisms linked to increased risk of CVD. Fibroblast growth factor 23 and parathyroid hormone (PTH) levels, both of which have been suggested to have direct pathogenic CV effects, increase in response to phosphate retention. Phosphate, calcium, and PTH levels are linked in a progressively worsening cycle. Maladaptive upregulation of phosphate absorption is also likely to occur further exacerbating hyperphosphatemia. Even higher phosphate levels within the normal range may be a risk factor for vascular calcification and, thus, CV morbidity and mortality. A greater degree of phosphate control is important to reduce the risk of CV morbidity and mortality. Improved phosphate control and regular monitoring of phosphate levels are guideline-recommended, established clinical practices. There are several challenges with the current phosphate management approaches in patients with CKD on dialysis. Dietary restriction of phosphate and thrice-weekly dialysis alone are insufficient/unreliable to reduce phosphate to <5.5 mg/dL. Even with the addition of phosphate binders, the only pharmacological treatment currently indicated for hyperphosphatemia, the majority of patients are unable to achieve and maintain phosphate levels <5.5 mg/dL (or more normal levels) [PhosLo® gelcaps (calcium acetate): 667 mg (prescribing information), 2011, VELPHORO®: (Sucroferric oxyhydroxide) (prescribing information), 2013, FOSRENAL®: (Lanthanum carbonate) (prescribing information), 2016, AURYXIA®: (Ferric citrate) tablets (prescribing information), 2017, RENVELA®: (Sevelamer carbonate) (prescribing information), 2020, RealWorld dynamix. Dialysis US: Spherix Global Insights, 2019]. Phosphate binders do not target the primary pathway of phosphate absorption (paracellular), have limited binding capacity, and bind nonspecifically [PhosLo® gelcaps (calcium acetate): 667 mg (prescribing information). 2013, VELPHORO®: (Sucroferric oxyhydroxide) (prescribing information), 2013, FOSRENAL®: (Lanthanum carbonate) (prescribing information), 2016, AURYXIA®: (Ferric citrate) tablets (prescribing information), 2017, RENVELA®: (Sevelamer carbonate) (prescribing information) 2020]. Key Messages: Despite current phosphate management strategies, most patients on dialysis are unable to consistently achieve target phosphate levels, indicating a need for therapeutic innovations [RealWorld dynamix. Dialysis US: Spherix Global Insights, 2019]. Given a growing evidence base that the dominant mechanism of phosphate absorption is the intestinal paracellular pathway, new therapies are investigating ways to reduce phosphate levels by blocking absorption through the paracellular pathway.

Metabolomic correlates of coronary atherosclerosis, cardiovascular risk, both or neither. Results of the 2 × 2 phenotypic CAPIRE study

BACKGROUND

Traditional cardiovascular risk factors (RFs) and coronary artery disease (CAD) do not always run parallel. We investigated functional-metabolic correlations of CAD, RFs, or neither in the CAPIRE (Coronary Atherosclerosis in Outlier Subjects: Protective and Novel Individual Risk Factors Evaluation) 2 × 2 phenotypic observational study.

METHODS

Two hundred and fortyone subjects were included based on RF burden, presence/absence of CAD (assessed by computed tomography angiography), age and sex. Participants displayed one of four phenotypes: CAD with ≥3 RFs, no-CAD with ≥3 RFs, CAD with ≤1 RF and no-CAD with ≤1 RF. Metabolites were identified by gas chromatography-mass spectrometry and pathways by metabolite set enrichment analysis.

RESULTS

Characteristic patterns and specific pathways emerged for each phenotypic group: amino sugars for CAD/high-RF; urea cycle for no-CAD/high-RF; glutathione for CAD/low-RF; glycine and serine for no-CAD/low-RF. Presence of CAD correlated with ammonia recycling; absence of CAD with the transfer of acetyl groups into mitochondria; high-risk profile with alanine metabolism (all p < 0.05). The comparative case-control analyses showed a statistically significant difference for the two pathways of phenylalanine, tyrosine and tryptophan biosynthesis and phenylalanine metabolism in the CAD/Low-RF vs NoCAD/Low-RF comparison.

CONCLUSIONS

The present 2 × 2 observational study identified specific metabolic pathways for each of the four phenotypes, providing novel functional insights, particularly on CAD with low RF profiles and on the absence of CAD despite high-risk factor profiles.

Differences between diabetic and non-diabetic nephropathy patients in cardiac structure and function at the beginning of hemodialysis and their impact on the prediction of mortality

OBJECTIVES

To characterize differences in cardiac structure and function in hemodialysis (HD) patients with diabetic nephropathy (DN) and in those without using echocardiography and to determine their impact on the prediction of mortality using echocardiographic parameters.

METHODS

Clinical, laboratory, and echocardiographic data were collected from patients commencing HD.

RESULTS

Compared with those without DN, patients with DN had lower peak velocity of the early diastolic wave (e'), larger left atria, and higher peak early diastolic velocity (E)/e' and peak velocity of tricuspid regurgitation (TR). In addition, a larger proportion of DN patients had a combination of left ventricular (LV) diastolic dysfunction, cardiac valve calcification, moderate-to-severe cardiac valve regurgitation (CVR), and at least moderate pericardial effusion (PE). After accounting for age, sex, smoking, hypertension, hemoglobin, and albumin, DN was responsible for e'  < 10 cm/s, E/e' >13 m/s, TR >2.8 m/s, LV diastolic dysfunction, CVR, and PE. LV diastolic dysfunction and E/e' >13 were the most useful predictors of mortality in patients with DN.

CONCLUSIONS

Patients with DN who undergo HD tend to have worse LV diastolic function and are more likely to have heart valve problems. LV diastolic dysfunction and E/e' are predictors of death in DN patients.

Serum Phosphorus Levels are Associated with Intradialytic Hypotension in Hemodialysis Patients

BACKGROUND

Intradialytic hypotension (IDH) is a common serious complication in hemodialysis (HD) patients. Hyperphosphatemia is also common in HD patients and promotes vascular calcification. Given the association between vascular calcification and IDH, we investigated the association between IDH and serum phosphorus in HD patients.

METHODS

We enrolled 173 patients who received HD for 3 months or more. IDH was defined as a nadir systolic blood pressure (SBP) <90 mm Hg or as a decrease in SBP ≥20 mm Hg or a decrease in mean arterial pressure by 10 mm Hg with the occurrence of hypotension-related symptoms requiring intervention. Serum phosphorus levels were analyzed both as a continuous variable and as a categorical variable.

RESULTS

IDH occurred in 40 (23.1%) of the 173 patients. The mean phosphorus level was 4.9 mg/dL. A 1 mg/dL higher serum phosphorus resulted in a 2.1-fold greater odds of IDH. The fully adjusted odds ratio (OR) and 95% confidence interval (CI) were 2.11 (1.48-3.01). High categorized phosphorus levels were also associated with IDH. The highest tertile of serum phosphorus was associated with 6.5-fold greater odds of developing IDH compared to the referent group (the middle tertile of serum phosphorus, 4.0-<5.3 mg/dL); the fully adjusted OR (95% CIs) were 6.53 (2.23-19.09). In subgroup analyses, diabetes and pre-dialysis SBP modified the association between IDH and phosphorus levels, with a more pronounced association in diabetic patients and pre-dialysis SBP ≥140 mm Hg.

CONCLUSION

In HD patients, higher phosphorus levels were associated with an increased occurrence of IDH.

Glucocorticoids dexamethasone and prednisolone suppress fibroblast growth factor 23 (FGF23)

Fibroblast growth factor 23 (FGF23) is a hormone mainly secreted by bone cells. Its most prominent effects are the regulation of renal phosphate reabsorption and calcitriol (active vitamin D, 1,25(OH)₂D₃) formation, effects dependent on its co-receptor αKlotho. Besides these actions, further paracrine and endocrine effects exist. The production of FGF23 is regulated by 1,25(OH)₂D₃, parathyroid hormone, dietary phosphate intake, iron status, as well as inflammation. Glucocorticoids are hormones with anti-inflammatory properties and are, therefore, widely used for acute and chronic inflammatory diseases, autoimmune disorders, and malignancies. The present study explored whether glucocorticoids influence the production of FGF23 in vitro as well as in mice. Fgf23 transcription was analyzed by semi-quantitative real-time PCR. Serum concentrations of FGF23 and 1,25(OH)₂D₃ were measured by ELISA. Urinary phosphate and Ca²⁺ excretion were determined in metabolic cages. As a result, in UMR106 rat osteoblast-like cells and in MC3T3-E1 cells, both, dexamethasone and prednisolone, downregulated Fgf23 transcription and FGF23 protein synthesis. Dexamethasone increased Dmp1 and Phex (encoding FGF23-regulating genes) as well as Nfkbia (encoding NFκB inhibitor IκBα) transcription in UMR106 cells. In mice, a single injection of dexamethasone or prednisolone was followed by a significant decrease of serum C-terminal and intact FGF23 concentration and bone Fgf23 mRNA expression within 12 h. These effects were paralleled by increased renal phosphate excretion and enhanced 1,25(OH)₂D₃ formation. We conclude that a single glucocorticoid treatment strongly downregulates the FGF23 plasma concentration. KEY MESSAGES: Glucocorticoids dexamethasone and prednisolone suppress the formation of bone-derived hormone fibroblast growth factor 23 (FGF23) in vitro. The effect is accompanied by an upregulation of Dmp1, Phex, and IκBα, negative regulators of FGF23, in UMR106 osteoblast-like cells. Glucocorticoid receptor antagonist RU-486 attenuates the effect of dexamethasone on FGF23, Dmp1, and Phex. In mice, a single glucocorticoid dose suppresses FGF23 and enhances 1,25(OH)₂D₃ (active vitamin D).

Assessment of Inorganic Phosphate Intake by the Measurement of the Phosphate/Urea Nitrogen Ratio in Urine

In chronic kidney disease (CKD) patients, it would be desirable to reduce the intake of inorganic phosphate (P) rather than limit the intake of P contained in proteins. Urinary excretion of P should reflect intestinal absorption of P(inorganic plus protein-derived). The aim of the present study is to determine whether the ratio of urinary P to urinary urea nitrogen (P/UUN ratio) helps identify patients with a high intake of inorganic P.A cross-sectional study was performed in 71 patients affected by metabolic syndrome with CKD (stages 2–3) with normal serum P concentration. A 3-day dietary survey was performed to estimate the average daily amount and the source of P ingested. The daily intake of P was 1086.5 ± 361.3 mg/day; 64% contained in animal proteins, 22% in vegetable proteins, and 14% as inorganic P. The total amount of P ingested did not correlate with daily phosphaturia, but it did correlate with the P/UUN ratio (p < 0.018). Patients with the highest tertile of the P/UUN ratio >71.1 mg/g presented more abundant inorganic P intake (p < 0.038).The P/UUN ratio is suggested to be a marker of inorganic P intake. This finding might be useful in clinical practices to identify the source of dietary P and to make personalized dietary recommendations directed to reduce inorganic P intake.

Safety and efficacy of sucroferric oxyhydroxide in pediatric patients with chronic kidney disease

BACKGROUND

Pediatric patients with advanced chronic kidney disease (CKD) are often prescribed oral phosphate binders (PBs) for the management of hyperphosphatemia. However, available PBs have limitations, including unfavorable tolerability and safety.

METHODS

This phase 3, multicenter, randomized, open-label study investigated safety and efficacy of sucroferric oxyhydroxide (SFOH) in pediatric and adolescent subjects with CKD and hyperphosphatemia. Subjects were randomized to SFOH or calcium acetate (CaAc) for a 10-week dose titration (stage 1), followed by a 24-week safety extension (stage 2). Primary efficacy endpoint was change in serum phosphorus from baseline to the end of stage 1 in the SFOH group. Safety endpoints included treatment-emergent adverse events (TEAEs).

RESULTS

Eighty-five subjects (2-18 years) were randomized and treated (SFOH, n = 66; CaAc, n = 19). Serum phosphorus reduction from baseline to the end of stage 1 in the overall SFOH group (least squares [LS] mean ± standard error [SE]) was - 0.488 ± 0.186 mg/dL; p = 0.011 (post hoc analysis). Significant reductions in serum phosphorus were observed in subjects aged ≥ 12 to ≤ 18 years (LS mean ± SE - 0.460 ± 0.195 mg/dL; p = 0.024) and subjects with serum phosphorus above age-related normal ranges at baseline (LS mean ± SE - 0.942 ± 0.246 mg/dL; p = 0.005). Similar proportions of subjects reported ≥ 1 TEAE in the SFOH (75.8%) and CaAc (73.7%) groups. Withdrawal due to TEAEs was more common with CaAc (31.6%) than with SFOH (18.2%).

CONCLUSIONS

SFOH effectively managed serum phosphorus in pediatric patients with a low pill burden and a safety profile consistent with that reported in adult patients.

Associations of the systolic and diastolic components of orthostatic hypotension with markers of cardiovascular risk in older men: A cross-sectional analysis from The British Regional Heart Study

The mechanisms underlying the association between orthostatic hypotension (OH) and cardiovascular disease are unclear. We investigated whether OH is associated with circulating cardiovascular risk markers. This was a cross-sectional analysis of 3857 older, community-dwelling men. "Consensus OH" was defined as a sitting-to-standing decrease in systolic blood pressure ≥20 mm Hg and/or diastolic blood pressure ≥10 mm Hg that occurred within three minutes of standing. Multiple generalized linear regression and logistic models were used to examine the association between cardiovascular risk markers and OH. Consensus OH was present in 20.2%, consisting of isolated systolic OH in 12.6%, isolated diastolic OH in 4.6%, and combined systolic and diastolic OH in 3.0%. Concentration of von Willebrand factor, a marker of endothelial dysfunction, was positively associated with isolated systolic OH (OR 1.35, 95% CI 1.05-1.73) and combined systolic and diastolic OH (OR 2.27, 95% CI 1.35-3.83); high circulating phosphate concentration, which may reflect vascular calcification, was associated with isolated diastolic OH (OR 1.53, 95% CI 1.04-2.25) and combined systolic and diastolic OH (OR 2.12, 95% CI 1.31-3.44), high-sensitivity troponin T, a marker of myocardial injury, was positively associated with isolated diastolic OH (OR 1.69, 95% CI 1.07-2.65) and N-terminal pro-brain natriuretic peptide, a marker of cardiac stress, was positively associated with combined systolic and diastolic OH (OR 2.14, 95% CI 1.14-4.03). In conclusion, OH is associated with some cardiovascular risk markers implicated in endothelial dysfunction, vascular calcification, myocardial injury, and cardiac stress. Clinicians should consider assessing cardiovascular risk in patients with OH.

Obesity and Other Nutrition Related Abnormalities in Pre-Dialysis Chronic Kidney Disease (CKD) Participants

Chronic kidney disease (CKD) is increasing in sub-Saharan Africa. Undernutrition has been prevalent amongst end stage CKD patients, with limited data on the prevalence of obesity. The aim of this study was to assess the nutritional status of CKD patients using various methods sensitive to over and under-nutrition. Stage 3 to 5 CKD patients (glomerular filtration rate (GFR) < 60 mL/min/1.73 m²) attending a pre-dialysis clinic in Cape Town, were enrolled. Exclusion criteria included infectious and autoimmune conditions. Sociodemographic, clinical and biochemical data were collected, and anthropometric measurements were performed. Dietary intake was measured with a quantified food frequency questionnaire (FFQ). Statistical Package for the Social Sciences (SPSS) version 26 was used for statistical analysis. Seventy participants, with mean age of 41.8 ± 11.8 years, 52.9% females and 47.1% males were enrolled. Participants enrolled mainly had stage 5 kidney failure. Thirty percent were overweight (21) and 25 (36%) were obese, 22 (60%) of females were overweight and obese, while 13 (39.4%) of males were predominantly normal weight. Abdominal obesity was found in 42 (60%) of participants, mainly in females. Undernutrition prevalence was low at 3%. Dietary assessment showed a high sugar and protein intake. There was a high prevalence of overweight, obesity and abdominal obesity in CKD stage 35 patients, with unhealthy dietary intake and other nutritional abnormalities.

Nutritional Guideline for the Management of Mexican Patients with CKD and Hyperphosphatemia

Chronic kidney disease (CKD) represents a serious concern for the Mexican population since the main predisposing diseases (diabetes, hypertension, etc.) have a high prevalence in the country. The development of frequent comorbidities during CKD such as anemia, metabolic disorders, and hyperphosphatemia increases the costs, symptoms, and death risks of the patients. Hyperphosphatemia is likely the only CKD comorbidity in which pharmaceutical options are restricted to phosphate binders and where nutritional management seems to play an important role for the improvement of biochemical and clinical parameters. Nutritional interventions aiming to control serum phosphate levels need to be based on food tables, which should be specifically elaborated for the cultural context of each population. Until now, there are no available food charts compiling a high amount of Mexican foods and describing phosphorus content as well as the phosphate to protein ratio for nutritional management of hyperphosphatemia in CKD. In this work, we elaborate a highly complete food chart as a reference for Mexican clinicians and include charts of additives and drug phosphate contents to consider extra sources of inorganic phosphate intake. We aim to provide an easy guideline to contribute to the implementation of more nutritional interventions focusing on this population in the country.

Ultra-Processed Food Consumption Is Associated with Abdominal Obesity: A Prospective Cohort Study in Older Adults

INTRODUCTION AND OBJECTIVES

Ultra-processed food (UPF) consumption has been associated with increased incidence of cardiovascular disease and its risk factors. The aim of this study was to assess, for the first time in the literature, the prospective association between UPF consumption and the incidence of abdominal obesity (AO) in older adults.

METHODS

The study sample consists of 652 participants in the Seniors Study on Nutrition and Cardiovascular Risk in Spain: Seniors-ENRICA-1 study, (mean age 67, 44% women). At baseline, standardized anthropometric measurements were collected (including abdominal circumference). After a median follow-up of six years, the abdominal circumference was measured again, and the incidence of abdominal obesity (AO) was calculated, defined as an abdominal perimeter ≥102 cm in men and ≥88 cm in women. At baseline, dietary information was collected using a computerized and validated dietary history. Information was obtained on the usual diet in the previous year. A total number of 880 foods were classified according to their degree of processing following the NOVA classification. Foods or drinks formulated mostly or entirely from substances derived from foods, with little or no presence of the unaltered original food were classified as UPF. For each participant, the percentage of energy from UPF was derived and sex-specific tertiles were calculated. Logistic regression models were built and adjusted for sociodemographic, lifestyle, morbidity, and drug treatment variables.

RESULTS

Among those participants without AO at baseline, 177 developed AO during follow-up. The average consumption of UPF was 17% of total energy (7% in the first tertile; 29% in the third tertile). The odds ratio (95% confidence interval) for incident AO risk when compared to the lowest tertile was: 1.55 (0.99-2.44) for the second tertile of UPF consumption and 1.62 (1.04-2.54) for the third tertile; p for linear trend: 0.037. Results remained statistically significant after adjusting for potential dietary confounding factors such as fiber consumption, the intake of very long chain omega-3 fatty acids and adherence to the Mediterranean diet.

CONCLUSIONS

A higher UPF consumption is positively associated with incident AO in older adults in Spain. These findings extend the current evidence of the detrimental effect of UPF consumption on cardiometabolic health.

Advances in management of chronic metabolic acidosis in chronic kidney disease

PURPOSE OF REVIEW

Chronic metabolic acidosis is a common complication of chronic kidney disease (CKD) and is associated with adverse consequences, such as CKD progression and muscle wasting. We review the findings from recent clinical trials that have examined the effects of sodium bicarbonate therapy and veverimer in patients with CKD and chronic metabolic acidosis.

RECENT FINDINGS

There are four recent clinical trials on chronic metabolic acidosis of CKD. In a pilot, cross-over study, 6 weeks of sodium bicarbonate therapy improved vascular endothelial function, measured by brachial artery flow-mediated dilation. In a single-center, randomized, open-label study, 6 months of sodium bicarbonate therapy increased muscle mass and lean body mass, and preserved kidney function. The other two clinical trials (phase 1/2 and phase 3 studies) examined the effects of veverimer, which is a hydrochloric acid binder. The phase 3 study showed that 12-weeks of veverimer increased serum bicarbonate levels and might improve physical function. The effects of veverimer on CKD progression, physical function and cardiovascular endpoints as well as its long-term safety are yet to be determined.

SUMMARY

Recent studies suggest that sodium bicarbonate therapy may improve vascular endothelial function and muscle mass, and preserve renal function. Veverimer increases serum bicarbonate level and could be a potential new therapeutic option for treating chronic metabolic acidosis.

Review of the diagnosis of gastrointestinal lanthanum deposition

Lanthanum carbonate is used for treatment of hyperphosphatemia mostly in patients with chronic renal failure. Although lanthanum carbonate is safe, recently, lanthanum deposition in the gastrointestinal mucosa of patients has been reported in the literature. This review provides an overview of gastroduodenal lanthanum deposition and focuses on disease’s endoscopic, radiological, and histological features, prevalence, and outcome, by reviewing relevant clinical studies, case reports, and basic research findings, to better understand the endoscopic manifestation of gastrointestinal lanthanum deposition. The possible relationship between gastric lanthanum deposition pattern and gastric mucosal atrophy is also illustrated; in patients without gastric mucosal atrophy, gastric lanthanum deposition appears as diffuse white lesions in the posterior wall and lesser curvature of the gastric body. In the gastric mucosa with atrophy, lanthanum-related lesions likely appear as annular or granular whitish lesions. Moreover, these white lesions are probably more frequently observed in the lower part of the stomach, where intestinal metaplasia begins.

Elastolytic activity of cysteine cathepsins K, S, and V promotes vascular calcification

Elastin plays an important role in maintaining blood vessel integrity. Proteolytic degradation of elastin in the vascular system promotes the development of atherosclerosis, including blood vessel calcification. Cysteine cathepsins have been implicated in this process, however, their role in disease progression and associated complications remains unclear. Here, we showed that the degradation of vascular elastin by cathepsins (Cat) K, S, and V directly stimulates the mineralization of elastin and that mineralized insoluble elastin fibers were ~25–30% more resistant to CatK, S, and V degradation when compared to native elastin. Energy dispersive X-ray spectroscopy investigations showed that insoluble elastin predigested by CatK, S, or V displayed an elemental percentage in calcium and phosphate up to 8-fold higher when compared to non-digested elastin. Cathepsin-generated elastin peptides increased the calcification of MOVAS-1 cells acting through the ERK1/2 pathway by 34–36%. We made similar observations when cathepsin-generated elastin peptides were added to ex vivo mouse aorta rings. Altogether, our data suggest that CatK-, S-, and V-mediated elastolysis directly accelerates the mineralization of the vascular matrix by the generation of nucleation points in the elastin matrix and indirectly by elastin-derived peptides stimulating the calcification by vascular smooth muscle cells. Both processes inversely protect against further extracellular matrix degradation.

Seasonal variation of serum 25-hydroxyvitamin D and parameters of bone and mineral disorder in dialysis patients

BACKGROUND

Vitamin D deficiency is common among dialysis patients and may impact blood concentrations of calcium, phosphorus, intact parathyroid hormone (iPTH), and alkaline phosphatase (ALP). Seasonal variation of serum 25-hydroxyvitamin D [25(OH)D] concentrations has been well established for the general population; however, less is known about circannual variation in 25(OH)D as well as other parameters of mineral and bone disorder among dialysis patients.

METHOD

Based on 57,500 serum 25(OH)D measurements collected over two years from January 2009 to December 2010 among 25,025 dialysis patients, we evaluated the circannual variations in serum concentrations of 25(OH)D, calcium, phosphorus, iPTH, and ALP by a linear regression model with a cosinor function for the time period (month). We adjusted for potential confounders including case-mix variables, and ultraviolet index.

RESULTS

Serum 25(OH)D concentrations showed significant circannual variation and mean serum 25(OH)D was 3.2 ng/mL higher in summer than in winter. Furthermore, 25(OH)D concentration increased steadily by 1.3 ng/mL per year. While serum calcium concentrations showed statistically significant but clinically negligible seasonal variation (0.02 mg/dL in peak-trough difference), serum phosphorus did not follow such a pattern. Serum iPTH concentrations also showed a modest seasonal variation with 9% higher values in winter than in summer. Concordantly, ALP concentrations in the winter were 2% higher than in the summer time. Seasonal variation of 25(OH)D was greater in male (vs. female), African-American (vs. non-African-American), and younger (vs. older) dialysis patients.

CONCLUSION

Serum 25(OH)D and iPTH concentrations show seasonal variation among dialysis patients while the variation in other parameters of mineral and bone disorder was clinically irrelevant, if any. Serum 25(OH)D also showed a gradual increase over time. Clinicians and researchers should be aware of these changes when interpreting laboratory results in dialysis patients.

Factors associated with carotid intima-media thickness in patients on maintenance hemodialysis

PURPOSE

The aim of this study was to analyze the association of the carotid intima-media thickness (CIMT) with various parameters in patients on maintenance hemodialysis (mHD).

METHODS

A cross-sectional study was conducted, enrolling 68 subjects (41 men, 27 women) on mHD in the Hemodialysis Unit, Sanglah Hospital, Denpasar, Indonesia. CIMT was measured with B-mode ultrasonography using a USG Sonoace 8000 and a 7.5 MHz linear transducer.

RESULTS

CIMT was higher in subjects with cardiovascular disease (CVD) compared with those without CVD (0.6494 vs 0.7288 mm; P=0.026), and in men compared with women (0.7056 vs 0.6141 mm; P=0.003). CIMT was correlated with age (R=0.607; P<0.001), plasma albumin (R=-0.291, P=0.016), serum phosphate (R=-0.294, P=0.015), calcium-phosphate product (R=-0.284, P=0.011), and plasma high-sensitivity C-reactive protein (R=0.279, P=0.030). However, after multiple linear regression testing, only age consistently had a role in determining the CIMT value (β=0.452, P<0.001).

CONCLUSION

Subjects with CVD have higher CIMT than those without CVD and men had higher CIMT than women. In addition, older age, higher high-sensitivity C-reactive protein, and lower albumin, phosphate, and calcium-phosphate product levels were correlated with higher CIMT. Age was the most important marker for CIMT in subjects on mHD.

Lack of vitamin D signalling per se does not aggravate cardiac functional impairment induced by myocardial infarction in mice

Epidemiological studies have linked vitamin D deficiency to an increased incidence of myocardial infarction and support a role for vitamin D signalling in the pathophysiology of myocardial infarction. Vitamin D deficiency results in the development of secondary hyperparathyroidism, however, the role of secondary hyperparathyroidism in the pathophysiology of myocardial infarction is not known. Here, we aimed to explore further the secondary hyperparathyroidism independent role of vitamin D signalling in the pathophysiology of myocardial infarction by inducing experimental myocardial infarction in 3-month-old, male, wild-type mice and in mice lacking a functioning vitamin D receptor. In order to prevent secondary hyperparathyroidism in vitamin D receptor mutant mice, all mice were maintained on a rescue diet enriched with calcium, phosphorus, and lactose. Surprisingly, survival rate, cardiac function as measured by echocardiography and intra-cardiac catheterisation and cardiomyocyte size were indistinguishable between normocalcaemic vitamin D receptor mutant mice and wild-type controls, 2 and 8 weeks post-myocardial infarction. In addition, the myocardial infarction-induced inflammatory response was similar in vitamin D receptor mutants and wild-type mice, as evidenced by a comparable upregulation in cardiac interleukin-1-β and tumor-necrosis-factor-α mRNA abundance and similar elevations in circulating interleukin-1-β and tumor-necrosis-factor-α. Our data suggest that the lack of vitamin D signalling in normocalcaemic vitamin D receptor mutants has no major detrimental effect on cardiac function and outcome post-myocardial infarction. Our study may have important clinical implications because it suggests that the secondary hyperparathyroidism induced by vitamin D deficiency, rather than the lack of vitamin D signalling per se, may negatively impact cardiac function post-myocardial infarction.

One-year efficacy and safety of the iron-based phosphate binder sucroferric oxyhydroxide in patients on peritoneal dialysis

Background

Sucroferric oxyhydroxide is a noncalcium, iron-based phosphate binder that demonstrated sustained serum phosphorus control, good tolerability and lower pill burden compared with sevelamer carbonate (sevelamer) in a Phase 3 study conducted in dialysis patients. This subanalysis examines the efficacy and tolerability of sucroferric oxyhydroxide and sevelamer in the peritoneal dialysis (PD) patient population.

Methods

The initial study (NCT01324128) and its extension (NCT01464190) were multicenter, Phase 3, open-label, randomized (2:1), active-controlled trials comparing sucroferric oxyhydroxide (1.0-3.0 g/day) with sevelamer (2.4-14.4 g/day) in dialysis patients over 52 weeks in total.

Results

In the overall study, 84/1055 (8.1%) patients received PD and were eligible for efficacy analysis (sucroferric oxyhydroxide, n = 56; sevelamer, n = 28). The two groups were broadly comparable to each other and to the overall study population. Serum phosphorus concentrations decreased comparably with both phosphate binders by week 12 (mean change from baseline - 0.6 mmol/L). Over 52 weeks, sucroferric oxyhydroxide effectively reduced serum phosphorus concentrations to a similar extent as sevelamer; 62.5% and 64.3% of patients, respectively, were below the Kidney Disease Outcomes Quality Initiative target range (≤1.78 mmol/L). This was achieved with a lower pill burden (3.4 ± 1.3 versus 8.1 ± 3.7 tablets/day) with sucroferric oxyhydroxide compared with sevelamer. Treatment adherence rates were 91.2% with sucroferric oxyhydroxide and 79.3% with sevelamer. The proportion of patients reporting at least one treatment-emergent adverse event was 86.0% with sucroferric oxyhydroxide and 93.1% with sevelamer. The most common adverse events with both treatments were gastrointestinal: diarrhea and discolored feces with sucroferric oxyhydroxide and nausea, vomiting and constipation with sevelamer.

Conclusions

Sucroferric oxyhydroxide is noninferior to sevelamer for controlling serum phosphorus in patients undergoing PD, while providing a relatively low pill burden and a high rate of adherence.

Elevated Phosphate Levels Trigger Autophagy-Mediated Cellular Apoptosis in H9c2 Cardiomyoblasts

BACKGROUND/AIM

In chronic kidney disease (CKD), kidneys fail to maintain phosphorus homeostasis in serum. Elevated phosphorus levels in serum have been associated with cardiovascular diseases in CKD patients and in normal individuals. In this study, we evaluated the level of autophagy- and apoptosis-related markers under different concentrations of hyperphosphate in myocardial cells.

METHODS

Modulation inflicted on the levels of various survival-, autophagy-, and apoptosis-related markers were determined by Western blotting analysis using total protein extract. FITC-annexin V staining was performed to quantify the apoptotic cells in all groups.

RESULTS

Hyperphosphate treatments showed to induce autophagy-related proteins beclin-1, ATG7, and LC3 II through the pAMPK-ULK1 pathway in Western blotting analysis. Further, apoptosis-associated proteins such as Bax, Bid, cytochrome c, and c-caspase-9 were also upregulated with hyperphosphate treatment. 3-Methyladenine, an autophagy inhibitor, inhibited apoptosis significantly in FITC-annexin V staining, and the inhibition of Bax, cytochrome c, and c-caspase-3 was shown by Western blotting.

CONCLUSION

The results suggest that hyperphosphate in H9c2 cardiomyoblasts would lead to cellular apoptosis via autophagy, which is mediated by the pAMPK signaling pathway. Our findings revealed the possible mechanism responsible for the heart damage under hyperphosphatemia.

The feasibility of in vivo detection of lanthanum using a 241Am K x-ray fluorescence system

OBJECTIVE

Lanthanum (La) is commonly used in phosphate binders in the form of lanthanum carbonate in patients with end-stage kidney disease undergoing hemodialysis treatments. With this administration, there is the potential for La storage in the body with bone being the main site of concern. However, the long-term effects of residual La in the body on bone health are not yet known. In this work, we investigate the feasibility of using a K x-ray fluorescence (K-XRF) spectroscopy system to measure bone La in vivo.

APPROACH

A series of hydroxyapatite (HAp) bone mineral phantoms were created to represent human bone. A 1.09 GBq ²⁴¹Am source was used to excite the HAp phantoms doped with various known concentrations of La placed in a 90° geometry relative to the photon source and high-purity germanium (HPGe) detector.

MAIN RESULTS

For a detector live time of 2000 s, the minimum detection limit was calculated to be 1.7 µg La g^-1 Ca or 0.7 µg La g^-1 HAp and is comparable to previously reported in vivo bone La concentrations.

SIGNIFICANCE

The technique developed in this study shows promising results and provides an alternative method to invasive biopsy sampling techniques to monitor the accumulation of bone La. To the best of our knowledge, this is the first reported work that seeks to non-invasively measure bone La via in vivo XRF.

Elevated serum phosphate levels are associated with decreased amputation-free survival after interventions for critical limb ischemia

OBJECTIVE

Elevated serum phosphate levels have been associated with increased risks of cardiovascular events and death in several patient populations. The effects of serum phosphate on outcomes in patients with critical limb ischemia (CLI) have not been evaluated. In this study, we assessed the effect of abnormal phosphate levels on mortality and major limb events after surgical intervention for CLI.

METHODS

A retrospective review was undertaken to identify all patients at a single institution who underwent a first-time open or endovascular intervention for CLI between 2005 and 2014. Patients without recorded postoperative phosphate levels were excluded. Postoperative phosphate levels ≤30 days of the initial operation were recorded, and the mean was calculated. Patients were stratified according to mean phosphate levels (low: <2.5 mg/dL, normal: 2.5-4.5 mg/dL, and high: >4.5 mg/dL). Patient demographics, comorbidities, and operative details were compared in univariate analysis. Multivariable regression and Cox proportional hazard modeling were used to account for patient demographics and comorbid conditions.

RESULTS

We identified 941 patients, including 42 (5%) with low phosphate, 768 (82%) with normal phosphate, and 131 (14%) with high phosphate. Patients with elevated phosphate were younger and had higher rates of congestive heart failure, diabetes, and dialysis dependence. Bypass was more common among patients with normal phosphate compared with high or low phosphate levels. There was no difference in the Wound, ischemia, and Foot infection (WiFi) classification or TransAtlantic Inter-Society Consensus classification among the cohorts. There were significant differences in 1-year mortality (low: 19%, normal: 17%, high: 33%; P < .01) and 3-year mortality (low: 38%, normal: 34%, high: 56%; P < .01) between phosphate cohorts. Major amputation (low: 12%, normal: 12%, high: 15%) and restenosis (low: 21%, normal: 24%, high: 28%) tended toward worse outcomes among patients with elevated phosphate levels but did not reach statistical significance. After adjustment for baseline characteristics, mortality was higher (hazard ratio [HR], 1.7; 95% confidence interval [CI], 1.3-2.2) and amputation-free survival was lower (HR, 1.5; 95% CI, 1.2-1.9) among patients with elevated compared with normal phosphate levels. A subgroup analysis was then performed to assess dialysis and nondialysis patients separately. Patients with elevated serum phosphate levels maintained a significantly higher risk of mortality in each group (dialysis: HR, 1.8; 95% CI, 1.2-2.6; nondialysis: HR, 1.5; 95% CI, 1.04-2.10).

CONCLUSIONS

Elevated phosphate levels are associated with increased mortality and decreased amputation-free survival after interventions for CLI. Future studies evaluating the effects of phosphate reduction in patients with CLI are warranted.

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.

Canaries in the Phosphate-Toxicity Coal Mines

Phosphorus is an essential mineral for cell structure and function but, when consumed in excess of the body's requirements, has many adverse effects on metabolism and health. Recently published research has revealed that the average American consumes far more phosphorus than the recommended dietary allowance (RDA) (700 mg/d for adults). Some individuals' daily phosphorus intake exceeds even an adult's tolerable upper limit (4000 mg/d). Until now, understanding of the adverse effects caused by high phosphorus intake has come from patients with chronic kidney disease (CKD), in whom high levels of serum phosphates are strongly associated with increased cardiovascular and all-cause mortality. Due to their impaired renal function, CKD patients cannot clear excess phosphorus, for which reason they must avoid processed foods, virtually all of which are laden with phosphate-containing food additives. Recently, it has become apparent that CKD patients are our canaries in the phosphate-toxicity coal mines. Excessive phosphorus consumption has now been shown to be clearly associated with cardiovascular disease, osteoporosis, and all-cause mortality in the general, healthy population.

Renal control of calcium, phosphate, and magnesium homeostasis

Calcium, phosphate, and magnesium are multivalent cations that are important for many biologic and cellular functions. The kidneys play a central role in the homeostasis of these ions. Gastrointestinal absorption is balanced by renal excretion. When body stores of these ions decline significantly, gastrointestinal absorption, bone resorption, and renal tubular reabsorption increase to normalize their levels. Renal regulation of these ions occurs through glomerular filtration and tubular reabsorption and/or secretion and is therefore an important determinant of plasma ion concentration. Under physiologic conditions, the whole body balance of calcium, phosphate, and magnesium is maintained by fine adjustments of urinary excretion to equal the net intake. This review discusses how calcium, phosphate, and magnesium are handled by the kidneys.

Regulation of serum phosphate

The regulation of serum phosphate, an acknowledged risk factor for chronic kidney disease and cardiovascular mortality, is poorly understood. The discovery of fibroblast growth factor 23 (FGF23) as a key regulator of renal phosphate handling and activation of vitamin D has revolutionized our comprehension of phosphate homeostasis. Through as yet undetermined mechanisms, circulating and dietary phosphate appear to have a direct effect on FGF23 release by bone cells that, in turn, causes renal phosphate excretion and decreases intestinal phosphate absorption through a decrease in vitamin D production. Thus, the two major phosphaturic hormones, PTH and FGF23, have opposing effects on vitamin D production, placing vitamin D at the nexus of phosphate homeostasis. While our understanding of phosphate homeostasis has advanced, the factors determining regulation of serum phosphate level remain enigmatic. Diet, time of day, season, gender, age and genetics have all been identified as significant contributors to serum phosphate level. The effects of these factors on serum phosphate have major implications for what is understood as 'normal' and for studies of phosphate homeostasis and metabolism. Moreover, other hormonal mediators such as dopamine, insulin-like growth factor, and angiotensin II also affect renal handling of phosphate. How the major hormone effects on phosphate handling are regulated and how the effect of these other factors are integrated to yield the measurable serum phosphate are only now beginning to be studied.

Effect of niacin on FGF23 concentration in chronic kidney disease

BACKGROUND

Elevated serum phosphorus and FGF23 are independent cardiovascular risk factors in patients with chronic kidney disease. In a randomized controlled trial of patients with dyslipidemia assigned to either extended release niacin (ERN) alone, ERN combined with the selective prostaglandin D2 receptor subtype 1 inhibitor laropiprant (ERN-L) or placebo, niacin lowered serum phosphorus; however, it is not known if it lowers FGF23 concentrations.

METHODS

This is an ancillary study to a multicenter, randomized, double-blind, placebo-controlled trial among patients with dyslipidemia and an estimated glomerular filtration rate (eGFR) of 30-74 ml/min/1.73 m(2). Participants were randomized to ERN-L (n = 162), ERN (n = 97), or placebo (n = 68) in a 3:2:1 ratio for 24 weeks. The primary outcome was a change in serum FGF23 concentrations, and secondary outcomes were changes in other mineral metabolism parameters.

RESULTS

Both the ERN and ERN-L groups showed significant declines in serum phosphorus, calcium and calcium·phosphorus product at 24 weeks compared to placebo. A significant decline from baseline (10.9%, p < 0.01) in the serum FGF23 concentration was observed in the ERN group compared to placebo, but not in the ERN-L group compared to placebo (p = 0.36 and 0.97 for ERN-L and placebo, respectively), despite equivalent declines in serum phosphorus. Similarly, the most marked declines in PTH occurred in the ERN-only group versus placebo; no change in PTH was observed in the ERN-L group.

CONCLUSIONS

In this ancillary study of hyperlipidemic patients with an eGFR of 30-74 ml/min/1.73 m(2), ERN alone but not in combination with laropiprant lowered FGF23 and PTH concentrations. If confirmed, niacin may provide a novel strategy to decrease phosphorus, FGF23, and PTH concentrations in patients with chronic kidney disease.

Associations among total and food additive phosphorus intake and carotid intima-media thickness--a cross-sectional study in a middle-aged population in Southern Finland

Background

Dietary phosphorus (P) intake in Western countries is 2- to 3-fold higher than recommended, and phosphate is widely used as a food additive in eg. cola beverages and processed meat products. Elevated serum phosphate concentrations have been associated with cardiovascular disease (CVD) risk factors and CVD itself in several studies in patients with renal dysfunction and in a few studies in the general population. Carotid intima-media thickness (IMT) is a CVD risk factor, thus the aim of the study was to determine if an association between dietary P, especially food additive phosphate (FAP), intake, and IMT exists.

Methods

Associations among total phosphorus (TP) and FAP intake and carotid IMT were investigated in a cross-sectional study of 37- to 47-year-old females (n = 370) and males (n = 176) in Finland. Associations among TP intake, FAP intake, and IMT were tested by analysis of covariance (ANCOVA) in quintiles (TP) and sextiles (FAP) using sex, age, low-density/high-density lipoprotein cholesterol ratio, smoking status, and IMT sonographer as covariates.

Results

No significant associations were present between TP or FAP intake and IMT (p > 0.05, ANCOVA), but in between-group comparisons some differences were found indicating higher IMT among subjects with higher P intake. When testing for a significant linear trend with contrast analysis, a positive trend was observed between energy-adjusted TP intake and IMT among all subjects (p = 0.039), and among females a tendency for a trend existed (p = 0.067). Among all subjects, a significant positive linear trend was also present between FAP intake and IMT (p = 0.022); this trend was also seen in females (p = 0.045). In males, no significant associations or trends were noted between TP or FAP intake and IMT (p > 0.05).

Conclusions

Our results indicate that a significant linear trend exists between energy-adjusted TP intake and FAP intake, and IMT among all subjects. Based on these results, high dietary P intake should be further investigated due to its potential association with adverse cardiovascular health effects in the general population.

Higher prevalence of morphometric vertebral fractures in patients with recent coronary events independently of BMD measurements

Cardiovascular disease and osteoporosis are important causes of morbi-mortality in the elderly and may be mutually related. Low bone mineral density (BMD) may be associated with increased risk of cardiovascular events. We investigated the prevalence of low bone mass and fractures in metabolic syndrome patients with acute coronary events. A case-control study was conducted with 150 individuals (30-80years-old) with metabolic syndrome. Seventy-one patients had had an acute coronary syndrome episode in the last 6months (cases) and the remaining 79 had no coronary event (controls). Cases and controls were matched for gender, BMI and age. DXA measurements and body composition were performed while spine radiographs surveyed for vertebral fractures and vascular calcification. Biochemical bone and metabolic parameters were measured in all patients. No statistically significant difference in BMD and the prevalence of osteopenia, osteoporosis and non-vertebral fractures was observed between cases and controls. The prevalence of vertebral fractures and all fractures was higher in the cases (14.1 versus 1.3%, p=0.003 and 22.5versus7.6%, p=0.010, respectively). Male gender (OR=0.22 95% CI 0.58 to 0.83, p=0.026) and daily intake of more than 3 portions of dairy products (OR=0.19 95% CI 0.49 to 0.75, p=0.017) were associated with lower prevalence of fractures. Cases had higher risk for fractures (OR=4.97, 95% CI 1.17 to 30.30, p=0.031). Bone mass and body composition parameters were not associated with cardiovascular risk factors or bone mineral metabolism. Patients with fragility fractures had higher OPG serum levels than those without fractures (p<0.001). Our findings demonstrated that patients with recent coronary events have a higher prevalence of vertebral fractures independently of BMD.

Clinical consequences of mutations in sodium phosphate cotransporters

Three families of sodium phosphate cotransporters have been described. Their specific roles in human health and disease have not been defined. Review of the literature reveals that the type II sodium phosphate cotransporters play a significant role in transepithelial transport in a number of tissues including kidney, intestine, salivary gland, mammary gland, and lung. The type I transporters seem to play a major role in renal urate handling and mutations in these proteins have been implicated in susceptibility to gout. The ubiquitously expressed type III transporters play a lesser role in phosphate homeostasis but contribute to cellular phosphate uptake, mineralization, and inflammation. The recognition of species differences in the expression, regulation, and function of these transport proteins suggests an urgent need to find ways to study them in humans.

Mutations in SLC20A2 link familial idiopathic basal ganglia calcification with phosphate homeostasis

Familial idiopathic basal ganglia calcification (IBGC) is a genetic condition with a wide spectrum of neuropsychiatric symptoms, including parkinsonism and dementia. Here, we identified mutations in SLC20A2, encoding the type III sodium-dependent phosphate transporter 2 (PiT2), in IBGC-affected families of varied ancestry, and we observed significantly impaired phosphate transport activity for all assayed PiT2 mutants in Xenopus laevis oocytes. Our results implicate altered phosphate homeostasis in the etiology of IBGC.

Phosphate Metabolism in Cardiorenal Metabolic Disease

Hyperphosphatemia is a major risk factor for cardiovascular disease, abnormalities of mineral metabolism and bone disease, and the progression of renal insufficiency in patients with chronic renal disease. In early renal disease, serum phosphate levels are maintained within the 'normal laboratory range' by compensatory increases in phosphaturic hormones such as fibroblast growth factor-23 (FGF-23). An important co-factor for FGF-23 is Klotho; a deficiency in Klotho plays an important role in the pathogenesis of hyperphosphatemia, renal tubulointerstitial disease, and parathyroid and bone abnormalities. Clinical hyperphosphatemia occurs when these phosphaturic mechanisms cannot counterbalance nephron loss. Hyperphosphatemia is associated with calcific uremic arteriolopathy and uremic cardiomyopathy, which may explain, in part, the epidemiologic connections between phosphate excess and cardiovascular disease. However, no clinical trials have been conducted to establish a causal relationship, and large, randomized trials with hard endpoints are urgently needed to prove or disprove the benefits and risks of therapy. In summary, hyperphosphatemia accelerates renal tubulointerstitial disease, renal osteodystrophy, as well as cardiovascular disease, and it is an important mortality risk factor in patients with chronic kidney disease.