Dietary magnesium supplementation inhibits abdominal vascular calcification in an experimental animal model of chronic kidney disease

Dietary magnesium supplementation in cats with chronic kidney disease: A prospective double-blind randomized controlled trial

BACKGROUND

Plasma total magnesium concentration (tMg) is a prognostic indicator in cats with chronic kidney disease (CKD), shorter survival time being associated with hypomagnesemia. Whether this risk factor is modifiable with dietary magnesium supplementation remains unexplored.

OBJECTIVES

Evaluate effects of a magnesium-enriched phosphate-restricted diet (PRD) on CKD-mineral bone disorder (CKD-MBD) variables.

ANIMALS

Sixty euthyroid client-owned cats with azotemic CKD, with 27 and 33 allocated to magnesium-enriched PRD or control PRD, respectively.

METHODS

Prospective double-blind, parallel-group randomized trial. Cats with CKD, stabilized on a PRD, without hypermagnesemia (tMg >2.43 mg/dL) or hypercalcemia (plasma ionized calcium concentration, (iCa) >6 mg/dL), were recruited. Both intention-to-treat and per-protocol (eating ≥50% of study diet) analyses were performed; effects of dietary magnesium supplementation on clinicopathological variables were evaluated using linear mixed effects models.

RESULTS

In the per-protocol analysis, tMg increased in cats consuming a magnesium-enriched PRD (β, 0.25 ± .07 mg/dL/month; P < .001). Five magnesium supplemented cats had tMg >2.92 mg/dL, but none experienced adverse effects. Rate of change in iCa differed between groups (P = .01), with decreasing and increasing trends observed in cats fed magnesium-enriched PRD and control PRD, respectively. Four control cats developed ionized hypercalcemia versus none in the magnesium supplemented group. Log-transformed plasma fibroblast growth factor-23 concentration (FGF23) increased significantly in controls (β, 0.14 ± .05 pg/mL/month; P = .01), but remained stable in the magnesium supplemented group (β, 0.05±.06 pg/mL/month; P =.37).

CONCLUSIONS AND CLINICAL IMPORTANCE

Magnesium-enriched PRD is a novel therapeutic strategy for managing feline CKD-MBD in cats, further stabilizing plasma FGF23 and preventing hypercalcemia.

Liver and spleen predominantly mediate calciprotein particle clearance in a rat model of chronic kidney disease

Calciprotein particles (CPPs) provide an efficient mineral buffering system to prevent the complexation of phosphate and calcium in the circulation. However, in chronic kidney disease (CKD), the phosphate load exceeds the mineral buffering capacity, resulting in the formation of crystalline CPP2 particles. CPP2 have been associated with cardiovascular events and mortality. Moreover, CPP2 have been demonstrated to induce calcification in vitro. In this study, we examined the fate of CPP2 in a rat model of CKD. Calcification was induced in Sprague-Dawley rats by 5/6 nephrectomy (5/6-Nx) combined with a high-phosphate diet. Control rats received sham surgery and high-phosphate diet. Twelve weeks after surgery, kidney failure was significantly induced in 5/6-Nx rats as determined by enhanced creatinine and urea plasma levels and abnormal kidney histological architecture. Subsequently, radioactive and fluorescent (FITC)-labeled CPP2 ([89Zr]Zr-CPP2-FITC) were injected intravenously to determine clearance in vivo. Using positron emission tomography scans and radioactive biodistribution measurements, it was demonstrated that [89Zr]Zr-CPP2-FITC are mainly present in the liver and spleen in both 5/6-Nx and sham rats. Immunohistochemistry showed that [89Zr]Zr-CPP2-FITC are predominantly taken up by Kupffer cells and macrophages. However, [89Zr]Zr-CPP2-FITC could also be detected in hepatocytes. In the different parts of the aorta and in the blood, low values of [89Zr]Zr-CPP2-FITC were detectable, independent of the presence of calcification. CPP2 are cleared rapidly from the circulation by the liver and spleen in a rat model of CKD. In the liver, Kupffer cells, macrophages, and hepatocytes contribute to CPP2 clearance.NEW & NOTEWORTHY Calciprotein particles (CPPs) buffer calcium and phosphate in the blood to prevent formation of crystals. In CKD, increased phosphate levels may exceed the buffering capacity of CPPs, resulting in crystalline CPPs that induce calcification. This study demonstrates that labeled CPPs are predominantly cleared from the circulation in the liver by Kupffer cells, macrophages, and hepatocytes. Our results suggest that targeting liver CPP clearance may reduce the burden of crystalline CPP in the development of vascular calcification.

Magnesium and Vascular Calcification in Chronic Kidney Disease: Current Insights

Magnesium (Mg) plays crucial roles in multiple essential biological processes. As the kidneys are the primary organ responsible for maintaining the blood concentration of Mg, people with chronic kidney disease (CKD) may develop disturbances in Mg. While both hyper- and hypomagnesemia may lead to adverse effects, the consequences associated with hypomagnesemia are often more severe and lasting. Importantly, observational studies have shown that CKD patients with hypomagnesemia have greater vascular calcification. Vascular calcification is accelerated and contributes to a high mortality rate in the CKD population. Both in vitro and animal studies have demonstrated that Mg protects against vascular calcification via several potential mechanisms, such as inhibiting the formation of both hydroxyapatite and pathogenic calciprotein particles as well as limiting osteogenic differentiation, a process in which vascular smooth muscle cells in the media layer of the arteries transform into bone-like cells. These preclinical findings have led to several important clinical trials that have investigated the effects of Mg supplementation on vascular calcification in people with CKD. Interestingly, two major clinical studies produced contradictory findings, resulting in a state of equipoise. This narrative review provides an overview of our current knowledge in the renal handling of Mg in health and CKD and the underlying mechanisms by which Mg may protect against vascular calcification. Lastly, we evaluate the strength of evidence from clinical studies on the efficacy of Mg supplementation and discuss future research directions.

Effect of magnesium on vascular calcification in chronic kidney disease patients: a systematic review and meta-analysis

PURPOSE

To evaluate the effects of magnesium (Mg) supplementation on vascular calcification (VC) in patients with chronic kidney disease (CKD).

METHODS

PubMed, Embase, Cochrane Library, Medline, Web of Science, CNKI, VIP, and WanFang databases were searched from build to July 2022. Randomized controlled trials (RCT) and non-RCT related to whether Mg supplementation inhibits VC in patients with CKD were included. The literature was screened according to inclusion and exclusion criteria, and quality evaluation and data collection were performed. Meta-analysis was performed using Review Manager 5.4 software.

RESULTS

8 RCTs and 1 non-RCT studies with a total of 496 patients were eventually included. Compared to control groups, Mg supplementation increased serum Mg levels (SMD = 1.26, 95% CI: -0.70 to 1.82, p < 0.001), but it was not statistically significant in alleviating the degree of VC, increasing T50, and reducing serum phosphorus (P) levels in patients with CKD (all p > 0.05). Oral Mg reduced left (WMD=-0.06, 95% CI. -0.11 to -0.01, p = 0.03) and right (WMD=-0.07, 95% CI: -0.13 to -0.01, p = 0.02) carotid intima-media thickness (cIMT). Additionally, calcium (Ca) (SMD=-0.43, 95% CI: -0.74 to -0.11, p = 0.008) and parathyroid hormone (PTH) (SMD=-0.43, 95% CI: -0.75 to -0.11, p = 0.008) levels were reduced by increasing dialysate Mg concentration.

CONCLUSIONS

Mg supplementation increased serum Mg levels and reduced Ca, PTH, and cIMT, but it did not reduce VC scores in patients with CKD. This still requires further studies with larger samples to evaluate the effect of Mg supplementation on VC.

Regulatory effects of nutritional and metabolic disorders on vascular calcification in chronic kidney disease: a narrative review

Background and Objective

Vascular calcification (VC) is common in chronic kidney disease (CKD) patients and is associated with poor cardiovascular outcomes. This study aims to review nutritive pro-calcifying factors of CKD.

Methods

Electronic databases (PubMed, Embase, and the Cochrane Central Register of Controlled Trials) were searched from 2001 as at July 26, 2022, to select and summarize the basic and clinical studies reporting the effects of malnutrition or metabolic disorders on VC in CKD and the evolving treatments for these nutrient metabolic disorders.

Key Content and Findings

Hyperphosphatemia, calcium load, hypomagnesemia, iron deficiency, lipoprotein(a) abnormalities, protein malnutrition, and vitamin K deficiency secondary to CKD were closely associated with the occurrence and development of VC. Elevated phosphate and calcium levels were essential contributors to VC, yet current phosphate binders with good phosphate-lowering effects had not been shown to delay VC progression in CKD, and it remained challenging on how to identify and prevent calcium overload. Magnesium supplementation was the most promising treatment for mitigating VC, as supported by in vitro and in vivo studies and clinical trials. Correction of iron and vitamin K deficiency might contribute to VC attenuation, yet there was a lack of clinical evidence on CKD patients.

Conclusions

This review highlighted the effects of nutrient metabolism disorders on CKD-VC, and additional studies are needed to further address optimal nutrition strategies for mitigating VC in CKD.

A national cross-sectional analysis of dietary copper intake and abdominal aortic calcification in the US adults: NHANES 2013-2014

BACKGROUND AND AIMS

Copper is an essential dietary element with a crucial role in physiological regulation. However, the relationship between dietary copper intake and abdominal aortic calcification (AAC) remains uncertain.

METHODS AND RESULTS

This study encompassed a cohort of 2535 adults aged over 40 years, derived from the National Health and Nutrition Examination Survey 2013-2014. Dietary copper intake from both food sources and supplements was assessed through two 24-h dietary recall interviews. AAC was measured by dual-energy X-ray absorptiometry and classified into 3 groups using the Kauppila score system. Multivariable logistic regression models were constructed to evaluate the association between dietary copper intake and AAC. Among the participants, a total of 771 individuals (30.4%) were diagnosed with AAC, of which 239 (9.4%) exhibited severe AAC. Higher dietary copper intake was significantly associated with a lower incidence of severe AAC. Specifically, for each 1 mg/day increase in dietary copper intake, the incidence of severe AAC decreased by 38% (odds ratios [OR] 0.62, 95% confidence intervals [CI] 0.39-0.98) after adjustment for relevant covariates. Moreover, individuals in the third tertile of copper intake had a 37% lower incidence of AAC compared to those in the first tertile [OR 0.63, 95% CI (0.43-0.95)]. However, no significant associations were found between supplemental copper intake or serum copper levels and AAC.

CONCLUSIONS

This study demonstrates that lower dietary copper intake, rather than serum copper levels or supplement copper intake, is significantly associated with a higher prevalence of AAC in adults ≥40 years old in the United States.

Pathophysiology and Clinical Impacts of Chronic Kidney Disease on Coronary Artery Calcification

The global prevalence of chronic kidney disease (CKD) has increased in recent years. Adverse cardiovascular events have become the main cause of life-threatening events in patients with CKD, and vascular calcification is a risk factor for cardiovascular disease. Vascular calcification, especially coronary artery calcification, is more prevalent, severe, rapidly progressive, and harmful in patients with CKD. Some features and risk factors are unique to vascular calcification in patients with CKD; the formation of vascular calcification is not only influenced by the phenotypic transformation of vascular smooth muscle cells, but also by electrolyte and endocrine dysfunction, uremic toxin accumulation, and other novel factors. The study on the mechanism of vascular calcification in patients with renal insufficiency can provide a basis and new target for the prevention and treatment of this disease. This review aims to illustrate the impact of CKD on vascular calcification and to discuss the recent research data on the pathogenesis and factors involved in vascular calcification, mainly focusing on coronary artery calcification, in patients with CKD.

Magnesium Administration in Chronic Kidney Disease

Awareness of the clinical relevance of magnesium in medicine has increased over the last years, especially for people with chronic kidney disease (CKD), due to magnesium's role in vascular calcification and mineral metabolism. The inverse association between serum magnesium and clinically relevant, adverse outcomes is well-established in people with CKD. Subsequent intervention studies have focused on the effect of magnesium administration, mainly in relation to cardiovascular diseases, mineral bone metabolism, and other metabolic parameters. The most commonly used routes of magnesium administration are orally and by increasing dialysate magnesium. Several oral magnesium formulations are available and the daily dosage of elemental magnesium varies highly between studies, causing considerable heterogeneity. Although data are still limited, several clinical studies demonstrated that magnesium administration could improve parameters of vascular function and calcification and mineral metabolism in people with CKD. Current clinical research has shown that magnesium administration in people with CKD is safe, without concerns for severe hypermagnesemia or negative interference with bone metabolism. It should be noted that there are several ongoing magnesium intervention studies that will contribute to the increasing knowledge on the potential of magnesium administration in people with CKD.

Is the magnesium phosphate ratio a predictor of arrhythmia in patients undergoing hemodialysis?

Aim: Koroner arter hastalığı, kalp yetmezliği, aritmi veya hiperkalemi nedenli ani ölüm son dönem böbrek yetmezliği hastalarında kardiyovasküler nedenlerin büyük çoğunluğunu oluşturmaktadır. Kanda bulunan Magnezyum, endotel fonksiyonu, damar tonusunun düzenlenmesi ve miyokardiyal uyarılabilirlik gibi kardiyovasküler fonksiyonları düzenleyen birçok süreçte önemli rol oynamaktadır. bu çalışmadaki amacımız; hemodiyaliz alan son dönem böbrek yetmezliği hastalarında Mg / P oranının aritmiyi öngörücülüğünü saptamaktır. Material and method: 18 yaşından büyük, kardiyoloji polikliniğine başvuran, kronik böbrek yetmezliği nedeniyle hemodiyaliz almakta olan ardışık 103 hasta çalışmaya dahil edildi. Ocak 2018 – Ekim 2022 tarihleri arasında 24 saatlik ritm holter ECG ile monitörize hastalar alındı. Hastalar 24 saatlik ritm holter EKG’ de aritmi saptananlar (grup 1: 51 hasta) ve saptanmayanlar (grup 2: 52 hasta) olarak 2 gruba ayrılarak analiz edildi. Result: Çalışmadaki hastaların yaş ortalamaları grup 1’ in grup 2’ ye kıyasla anlamlı daha yüksekti (66.96±10,27 ve 62,21±10,50, p=0.02, sırasıyla). Hastaların 24 saatlik ritm Holter EKG’ leri incelendiğinde en sık izlenen aritmi %18.4 (n=19)’ lük oran ile ventriküler ekstrasistol iken ikinci sırada %9.7 (n=10)’ lik oranı ile paroksismal AF’ ydi. ROC curve analizi (Resim-1) göstermiştir ki LVEF

The kidney reabsorption-related Magnesium Depletion Score is associated with increased likelihood of abdominal aortic calcification among US adults

BACKGROUND

Kidney reabsorption has a vital role in magnesium homeostasis. This study aimed to determine the relationship between the kidney reabsorption-related magnesium depletion score (MDS) and abdominal aortic calcification (AAC).

METHODS

We obtained the data of 2640 individuals from the National Health and Nutrition Examination Survey (NHANES) database and analyzed the relationship between MDS and AAC scores. MDS is a scoring system developed to predict status of magnesium deficiency that fully considered the pathophysiological factors influencing the kidneys' reabsorption capability. AAC was quantified by the Kauppila score system based on dual-energy X-ray absorptiometry. We performed stratified analysis and multiple equation regression analysis. R and EmpowerStats were used for data analysis.

RESULTS

A total of 2640 participants were included with the mean AAC score of 1.47 ± 0.07. Participants in higher MDS tended to have higher AAC scores (MDS scored 0: 0.75 (0.56, 0.93), MDS scored 1: 1.02 (0.84, 1.21), MDS scored 2: 2.34 (1.80, 2.87), MDS scored 3: 3.19 (2.46, 3.92), MDS ≥ 4: 4.99 (3.49, 6.49)). Compared with those in the lowest MDS scored 0, the highest subgroup (MDS ≥ 4) was associated with a higher AAC score (β = 4.24, 95% CI: 2.78-5.70, p < 0.001), and the association was not altered (β = 1.81, 95% CI: 0.54-3.09, p = 0.002) after adjusting for numerous covariates. Subgroup analyses showed that stronger associations between MDS and AAC score were detected in adults with lower levels of magnesium intake and older (all p for interaction < 0.05).

CONCLUSIONS

The MDS is a promising tool for identifying individuals with magnesium deficiency status who may benefit from dietary magnesium supplementation to reduce the risks of AAC.

Fibroblast growth factor 23 is independently associated with renal magnesium handling in patients with chronic kidney disease

BACKGROUND

Disturbances in magnesium homeostasis are common in patients with chronic kidney disease (CKD) and are associated with increased mortality. The kidney is a key organ in maintaining normal serum magnesium concentrations. To this end, fractional excretion of magnesium (FEMg) increases as renal function declines. Despite recent progress, the hormonal regulation of renal magnesium handling is incompletely understood. Fibroblast Growth Factor 23 (FGF23) is a phosphaturic hormone that has been linked to renal magnesium handling. However, it has not yet been reported whether FGF23 is associated with renal magnesium handling in CKD patients.

METHODS

The associations between plasma FGF23 levels, plasma and urine magnesium concentrations and FEMg was investigated in a cross-sectional cohort of 198 non-dialysis CKD patients undergoing renal biopsy.

RESULTS

FGF23 was significantly correlated with FEMg (Pearson's correlation coefficient = 0.37, p<0.001) and urinary magnesium (-0.14, p=0.04), but not with plasma magnesium. The association between FGF23 and FEMg remained significant after adjusting for potential confounders, including estimated glomerular filtration rate (eGFR), parathyroid hormone and 25-hydroxyvitamin D.

CONCLUSIONS

We report that plasma FGF23 is independently associated with measures of renal magnesium handling in a cohort of non-dialysis CKD patients. A potential causal relationship should be investigated in future studies.

Influencing factors of serum magnesium in CKD5 patients: A multicenter study in southern China

INTRODUCTION

Magnesium (Mg) disturbances are related to cardiac, bone, and renal patient mortality. In this study, we compared biochemical markers in hemodialysis (HD) and peritoneal dialysis (PD) patients and explored the influencing factors of serum Mg in stage 5 chronic kidney disease (CKD5) patients.

MATERIAL AND METHODS

All 598 patients with CKD5 from three medical centers in South China were recruited into this prospective cohort study from March 1, 2018, to January 31, 2021. Our study recorded the clinical characteristics and laboratory data of the patients.

RESULTS

Hemodialysis patients (0.99 ± 0.19 mmol/L) had a higher mean serum Mg level than PD patients (0.86 ± 0.20 mmol/L; p < 0.01). Regression analysis showed that only corrected calcium (Ca), phosphate (P), Ca/Mg, Ca × P, albumin (Alb), total protein and creatine (Cr) predicted Mg levels in CKD5 patients (p < 0.01). Ca/Mg predicts hypomagnesemia with 78% sensitivity and 85% specificity in CKD5 patients. The AUC value corresponding to Ca/Mg was 0.88.

CONCLUSIONS

This multicenter study in southern China showed that for all CKD5 patients, corrected Ca and Alb had a significant positive effect on serum Mg, while Ca/Mg had a significant negative effect on serum Mg. In 123 HD patients, Ca × P was positively associated with Mg while Ca/Mg and P were negatively associated with Mg. In 398 PD patients, Ca × P, Alb, and total protein were positively associated with Mg while Ca/Mg and P were negatively associated with Mg. In 77 non-dialysis patients, corrected Ca, Cr, and total protein were positively associated with Mg while Ca/Mg was negatively associated with Mg. Furthermore, Ca/Mg might be another useful technique to monitor blood Mg levels in CKD5 patients.

CLINICAL TRIAL REGISTRATION

ChiCTR1800014557.