Serum Magnesium and Sudden Death in European Hemodialysis Patients

Personalizing electrolytes in the dialysis prescription: what, why and how?

Maintenance hemodialysis patients suffer from multiple comorbidities and treatment-related complications. A personalized approach to hemodialysis prescription could reduce some of these burdens by preventing complications such as excessive changes in blood pressure, arrhythmias, post-dialysis fatigue and decreased quality of life. A patient-centered approach to dialysate electrolyte concentrations represents one such opportunity. In addition to modifications in dialysate electrolyte concentrations, consideration of individual factors such as patients' serum concentrations, medication profiles, nutritional status and comorbidities is critical to tailoring hemodialysis prescriptions to optimize patient outcomes. The development of personalized dialysis treatment depends on the collection of comprehensive patient data, advances in technology, resource allocation and patient involvement in decision-making. This review discusses how the treatment of maintenance hemodialysis patients could benefit from individualized changes in certain dialysis fluid components.

Serum Magnesium Levels and Cardiovascular Outcomes in Systolic Blood Pressure Intervention Trial Participants

Rationale and Objective

Serum magnesium levels have been inversely yet inconsistently associated with cardiovascular (CV) outcomes. In this study, we examined the association of serum magnesium levels with CV outcomes in the Systolic Blood Pressure Intervention Trial (SPRINT) participants.

Study Design

Case-control post hoc analysis of SPRINT.

Setting & Participants

A total of 2,040 SPRINT participants with available serum samples at baseline level were included in this study. Case participants (n = 510) who experienced a CV event during the SPRINT observation period (median follow-up of 3.2 years) and control participants (n = 1,530) without CV events were sampled in a 1:3 ratio for measurements of serum magnesium level at baseline and 2-year follow-up.

Predictors

Baseline serum magnesium levels and 2-year percentage change in serum magnesium levels (ΔSMg).

Outcome

SPRINT primary composite CV outcome.

Analytical Approach

Multivariable conditional logistic regression analysis, accounting for matching factors, was used to evaluate the association of baseline and ΔSMg with CV outcomes. Individual matching of cases and controls was based on the SPRINT treatment arm allocation (standard vs intensive) and prevalence of chronic kidney disease (CKD).

Results

The median serum magnesium level at baseline was similar among the case and control groups. In a fully adjusted model, each standard deviation (SD) (0.18 mg/dL) higher of the baseline serum magnesium level was independently associated with a lower risk for composite CV outcomes in all study participants (adjusted odds ratio 95% CI, 0.79 [0.70-0.89]). This association was similar when serum magnesium levels were analyzed in quartiles but dissipated in the standard (vs intensive) arm of SPRINT (0.88 [0.76-1.02] vs 0.65 [0.53-0.79], respectively; Pinteraction = 0.06). The presence or absence of CKD at baseline did not modify this association. ΔSMg was not independently associated with CV outcomes occurring after 2 years.

Limitations

ΔSMg was small in magnitude, limiting effect size.

Conclusions

Higher baseline serum magnesium levels were independently associated with reduced risk for CV outcomes in all study participants, but ΔSMg was not associated with CV outcomes.

Lower serum magnesium is a predictor of left ventricular hypertrophy in patients on dialysis

PURPOSE

Left ventricular hypertrophy (LVH) represents one of the main risk factors for cardiovascular mortality in dialysis patients. Low serum magnesium Mg is related with increased mortality in general and dialysis population. Aim of our study was to evaluate the association of Mg with LVH and cardiac geometry in dialysis patients.

METHODS

Hemodialysis (HD) and peritoneal dialysis (PD) patients from nine nephrology departments were included. Echocardiographic LVH was defined by LV mass index > 95 g/m² in women and > 115 g/m² in men. Four LV geometric patterns were defined: normal, concentric remodeling, eccentric LVH and concentric LVH. Demographic and laboratory data were collected.

RESULTS

133 patients (68 HD, 65 PD) with a median age of 63 years (IQR 52-74) were studied. Mg correlated positively with creatinine, HDL and negatively with CRP levels and BMI. There were no significant differences in Mg between the modality groups. 80 patients presented LVH (43 HD and 37 PD patients). Patients with LVH were older (median age 68 vs 55 years, p < 0.001), with higher BMI (median 26.9 vs 24.7 kg/m², p = 0.009), had a history of PVD or CAD (55% vs 30.2%, p = 0.003), had higher pulse pressure (median 60 vs 50, p = 0.017), MIS score (median 5 vs 4, p = 0.011), lower albumin (median 3.5 vs 3.8 g/dl, p = 0.011) and Mg levels (median 2.1 vs 2.4 mg/dl, p < 0.001). In univariate analysis age, CVD comorbidities, pulse pressure, CRP, BMI, albumin, Mg, MIS and use of b-blockers or calcium blockers were LVH predictors. In multivariate analysis, Mg was an independent predictor of LVH, adjusted for age, MIS and b-blockers. Considering LV geometry, lower Mg levels were mainly correlated with concentric LVH.

CONCLUSION

Low serum magnesium levels seem to be an independent factor for LVH in hemodialysis and peritoneal dialysis patients.

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

Magnesium in chronic haemodialysis (MAGIC-HD): a study protocol for a randomised controlled trial to determine feasibility and safety of using increased dialysate magnesium concentrations to increase plasma magnesium concentrations in people treated with haemodialysis

INTRODUCTION

People treated with haemodialysis are at increased risk for all-cause and cardiovascular mortality. Plasma magnesium concentration has been inversely associated with these risks. Therefore, plasma magnesium may be a new modifiable risk factor and an increase of dialysate magnesium concentration may be an easy, safe and effective way to increase plasma magnesium concentrations. Detailed information on modulating dialysate magnesium concentrations is limited in literature. Primary objective of this study is to determine the safety and feasibility to increase plasma magnesium concentrations in people treated with haemodialysis by means of sequentially increasing concentration of magnesium in the dialysate.

METHODS AND ANALYSIS

In this randomised double-blinded standard of care controlled trial, 53 persons treated with haemodialysis will be randomly allocated 2:1 to either a stepwise individually titrated increase of dialysate magnesium concentration from 0.50 to 0.75 to 1.00 mmol/L during 8 weeks, or a standard dialysate magnesium concentration of 0.50 mmol/L. Other study measurements include dietary records, questionnaires, ECG, Holter registration and pulse wave velocity. The primary endpoint is predialysis plasma magnesium after the long interdialytic interval at the end of week 8. In addition, the predictive effect of dialysate magnesium concentration and other baseline parameters and dialysis characteristics on plasma magnesium concentration will be explored using linear mixed models. Safety endpoint is defined by the occurrence of hypermagnesemia above 1.25 mmol/L, or bradycardia or prolonged QTc interval detected on the ECG.

ETHICS AND DISSEMINATION

The study is conducted in accordance with the declaration of Helsinki as revised in 2013 and was approved by the Ethical Committee of the VU University Medical Centre. The results of the study will be disseminated by publication in peer-reviewed scientific journals and presentation at national or international conferences in the field of interest.

TRIAL REGISTRATION NUMBER

NTR6568/NL6393.

Association between hypomagnesemia and mortality among dialysis patients: a systematic review and meta-analysis

Background

Malnutrition-inflammation-atherosclerosis (MIA) syndrome is caused by the inflammatory cytokines in end stage renal disease (ESRD) patients, and MIA complex-related factors may be associated with hypomagnesemia and mortality. However, the association between serum magnesium level and mortality for dialysis patients is still not clear. Additionally, no meta-analysis has investigated the impact of serum magnesium on peritoneal dialysis and hemodialysis, separately.

Methods

We searched published studies in PubMed, Embase, Cochrane, Collaboration Central Register of Controlled Clinical Trials, and Cochrane Systematic Reviews through April 2022. Studies associated with serum magnesium and all-cause mortality or cardiovascular (CV) mortality in ESRD on kidney replacement therapy (KRT) patients were included. A hazard ratio (HR) with 95% confidence intervals (CI) was used to report the outcomes.

Results

Twenty-one studies involving 55,232 patients were included. Overall, there was a significant association between hypomagnesemia and all-cause mortality for dialysis patients (HR: 1.67, 95% CI [1.412-2.00], p < 0.001; certainty of evidence: moderate) using a mixed unadjusted and adjusted HR for analysis. There was also a significantly increased risk of CV mortality for individuals with hypomagnesemia compared with the non-hypomagnesemia group (HR 1.56, 95% CI [1.08-2.25], p < 0.001; certainty of evidence: moderate). In addition, a subgroup analysis demonstrated that hypomagnesemia was associated with a high risk of both all-cause mortality and CV mortality (all-cause mortality, HR:1.80, 95% CI [1.48-2.19]; CV mortality, HR:1.84, 95% CI [1.10-3.07]) in hemodialysis (HD) patients, but not in participants receiving peritoneal dialysis (PD; all-cause mortality, HR:1.26, 95% CI [0.84-1.91]; CV mortality, HR:0.66, 95% CI [0.22-2.00]). The systematic review protocol was prespecified and registered in PROSPERO [CRD42021256187].

Conclusions

Hypomagnesemia may be a significant risk factor for all-cause mortality and CV mortality in KRT patients, especially in those receiving hemodialysis. However, because of the limited certainty of evidence, more studies are required to investigate this association.

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

BACKGROUND

Vascular calcification is a key process involved in cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). Magnesium supplementation may counteract vascular calcification. In this study we aimed to determine whether increased dietary magnesium intake inhibits vascular calcification in CKD in vivo and explore the mechanisms underlying these effects.

METHODS

Sprague Dawley rats were partially nephrectomized and fed a diet with high phosphate and either high or normal magnesium content for 16 weeks. The primary outcome was the tissue calcium content of the aorta in the high versus normal dietary magnesium group. In addition, we analysed plasma mineral concentrations, aortic vascular calcification identified with von Kossa staining, calcium apposition time and aortic expression of genes related to vascular calcification.

RESULTS

The number of animals in the highest tissue calcium content tertile was significantly lower in the abdominal aorta [1 (10%) versus 6 (55%); P = .03] in the high versus normal dietary magnesium group, but did not differ in the aortic arch and thoracic aorta. Von Kossa staining and calcium apposition time corresponded to these results. The median tissue calcium content was not significantly different between the groups. Serum phosphate concentrations and expression of osteogenic markers in the aorta did not differ between the groups.

CONCLUSIONS

This study demonstrates that increased dietary magnesium inhibits abdominal vascular calcification in an experimental animal model of CKD in vivo. These are promising results for CKD patients and further study is needed to identify the mechanisms involved and to determine the clinical relevance in patients.

Magnesium to prevent kidney disease-associated vascular calcification: crystal clear?

Vascular calcification is a prognostic marker for cardiovascular mortality in chronic kidney disease (CKD) patients. In these patients, magnesium balance is disturbed, mainly due to limited ultrafiltration of this mineral, changes in dietary intake and the use of diuretics. Observational studies in dialysis patients report that a higher blood magnesium concentration is associated with reduced risk to develop vascular calcification. Magnesium prevents osteogenic vascular smooth muscle cell transdifferentiation in in vitro and in vivo models. In addition, recent studies show that magnesium prevents calciprotein particle maturation, which may be the mechanism underlying the anti-calcification properties of magnesium. Magnesium is an essential protective factor in the calcification milieu, which helps to restore the mineral-buffering system that is overwhelmed by phosphate in CKD patients. The recognition that magnesium is a modifier of calciprotein particle maturation and mineralization of the extracellular matrix renders it a promising novel clinical tool to treat vascular calcification in CKD. Consequently, the optimal serum magnesium concentration for patients with CKD may be higher than in the general population.

Associations between the serum magnesium and all-cause or cardiovascular mortality in chronic kidney disease and end-stage renal disease patients: A meta-analysis

BACKGROUND

Some studies have found that hypomagnesemia is associated with vascular calcification, atherosclerosis, and cardiovascular disease, which may lead to increased mortality in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) who need to maintain hemodialysis (HD). However, the conclusion of these studies remain controversial.

METHODS

Relevant literature was retrieved from the database of Cochrane library, PubMed, EMBASE, and CNKI until December 2020, without any language restrictions. The data was analyzed using the Stata 12.0 software.

RESULTS

A total of 31 studies were included, involving 205436 participants. The results showed that after multivariable adjusted, hypomagnesemia was significant associated with the risk of all-cause mortality in patients with CKD and end-stage renal disease (ESRD) (hazard ratios [HR] 1.955; 95% confidence interval (95% CI) 1.511-2.528; P = .000; hypomagnesemia vs normal magnesium or hypermagnesemia). In contrast, in patients with CKD and ESRD, hypermagnesemia was negatively correlated with all-cause mortality (HR 0.873; 95% CI 0.793-0.960; P = .005) (per unit increase). Moreover, in the adjusted model, it was observed that hypermagnesemia was significantly associated with a reduced risk of cardiovascular death (HR 0.598; 95% CI 0.094-1.102, P = .020). In addition, subgroup analysis found that hypomagnesemia was closely related to the increase of all-cause mortality in HD patients (HR 1.799; 95% CI 1.375-2.354; P = .000) (hypomagnesemia vs normal magnesium or hypermagnesemia).

CONCLUSION

Our results show that hypomagnesemia is significantly associated with cardiovascular and all-cause mortality in maintenance HD patients. Further studies should be conducted to evaluate the benefits of magnesium correction in maintenance dialysis patients with hypomagnesemia.

Sudden cardiac death in dialysis patients: different causes and management strategies

Sudden cardiac death (SCD) represents a major cause of death in end-stage kidney disease (ESKD). The precise estimate of its incidence is difficult to establish because studies on the incidence of SCD in ESKD are often combined with those related to sudden cardiac arrest (SCA) occurring during a haemodialysis (HD) session. The aim of the European Dialysis Working Group of ERA-EDTA was to critically review the current literature examining the causes of extradialysis SCD and intradialysis SCA in ESKD patients and potential management strategies to reduce the incidence of such events. Extradialysis SCD and intradialysis SCA represent different clinical situations and should be kept distinct. Regarding the problem, numerically less relevant, of patients affected by intradialysis SCA, some modifiable risk factors have been identified, such as a low concentration of potassium and calcium in the dialysate, and some advantages linked to the presence of automated external defibrillators in dialysis units have been documented. The problem of extra-dialysis SCD is more complex. A reduced left ventricular ejection fraction associated with SCD is present only in a minority of cases occurring in HD patients. This is the proof that SCD occurring in ESKD has different characteristics compared with SCD occurring in patients with ischaemic heart disease and/or heart failure and not affected by ESKD. Recent evidence suggests that the fatal arrhythmia in this population may be due more frequently to bradyarrhythmias than to tachyarrhythmias. This fact may partly explain why several studies could not demonstrate an advantage of implantable cardioverter defibrillators in preventing SCD in ESKD patients. Electrolyte imbalances, frequently present in HD patients, could explain part of the arrhythmic phenomena, as suggested by the relationship between SCD and timing of the HD session. However, the high incidence of SCD in patients on peritoneal dialysis suggests that other risk factors due to cardiac comorbidities and uraemia per se may contribute to sudden mortality in ESKD patients.

Low plasma magnesium concentration and future abdominal aortic calcifications in moderate chronic kidney disease

BACKGROUND

Higher plasma magnesium concentrations are associated with reduced cardiovascular disease risk in chronic kidney disease (CKD) patients. The importance of plasma magnesium concentration for vascular calcification in earlier stages of CKD remains underexplored. This study investigated whether plasma magnesium is a determinant for the presence and severity of vascular calcification in moderate CKD.

METHODS

Retrospective analysis was performed using abdominal aortic calcification (AAC) scores in 280 patients with stage 3 and 4 CKD enrolled in the MASTERPLAN trial. Lateral abdominal X-ray was used to evaluate AAC. Plasma magnesium concentration were measured over time. A zero-inflated Poisson model determined the association between plasma magnesium concentration and AAC.

RESULTS

79 out of 280 patients did not have AAC, and in patients with AAC the median calcification score was 3.5 (interquartile range: 0.0-8.6). The mean plasma magnesium concentration was 0.76 ± 0.10 mmol/L at baseline. A 0.1 mmol/L higher plasma magnesium concentration was associated with lower AAC of 0.07 point (95% CI -0.28 - 0.14). A 0.1 mmol/L higher plasma magnesium lowered the odds of detecting any AAC by 30% (OR = 0.63; 95% CI 0.29-1.37). After 1 year and 4 years (at time of X-ray) of follow-up this association was attenuated (OR = 0.93; 95% CI 0.61-1.43 and 0.93; 95% CI 0.60-1.45, respectively). None of these associations reached statistical significance.

CONCLUSIONS

Plasma magnesium concentration at baseline is not associated with the risk for future AAC. Interventions increasing magnesium to avoid vascular calcification may have greatest potential in early CKD stages prior to onset of vascular calcification.

The association between circulating magnesium and clinically relevant outcomes in patients with chronic kidney disease: A systematic review and meta-analysis

BACKGROUND & AIMS

Despite modern treatment, risk for cardiovascular disease and mortality in patients with chronic kidney disease (CKD) is unacceptably high. Observational studies have shown associations of magnesium with risk for several clinical outcomes in CKD of variable magnitude. The aim of this review is to provide a systematic overview and meta-analysis of longitudinal studies assessing the association of plasma magnesium concentration with clinically relevant outcomes in adult patients with chronic kidney disease, with a minimal follow-up of 6 months. Primary outcomes of interest were all-cause mortality, cardiovascular mortality, cardiovascular events, sudden death and hospitalisation.

METHODS

The electronic databases PubMed, Embase and The Cochrane Library were searched using terms relating to plasma magnesium and CKD patients, and two authors independently selected eligible studies. Study quality was assessed according to the Newcastle-Ottawa Scale. Results of studies with a comparable magnesium exposure and outcome measure, were pooled using a random-effects meta-regression analysis.

RESULTS

The search yielded 6156 records of which 33 studies, involving 348,059 patients, met the eligibility criteria. Finally, 22 studies could be included in the meta-analysis. Higher magnesium was associated with a lower risk for all-cause mortality (HR 0.90 [0.87-0.94] per 0.1 mmol/L increase of magnesium) and cardiovascular mortality and events (HR 0.85 [0.77-0.94] per 0.1 mmol/L).

CONCLUSIONS

Magnesium concentration is inversely associated with all-cause mortality and cardiovascular mortality and events. Therefore, increasing magnesium may improve risk in patients with chronic kidney disease. This meta-analysis forms a firm base for future prospective trials to test whether increasing plasma magnesium, indeed has beneficial effects on clinical outcomes.

The Role of Disturbed Mg Homeostasis in Chronic Kidney Disease Comorbidities

Some of the critical mechanisms that mediate chronic kidney disease (CKD) progression are associated with vascular calcifications, disbalance of mineral metabolism, increased oxidative and metabolic stress, inflammation, coagulation abnormalities, endothelial dysfunction, or accumulation of uremic toxins. Also, it is widely accepted that pathologies with a strong influence in CKD progression are diabetes, hypertension, and cardiovascular disease (CVD). A disbalance in magnesium (Mg) homeostasis, more specifically hypomagnesemia, is associated with the development and progression of the comorbidities mentioned above, and some mechanisms might explain why low serum Mg is associated with negative clinical outcomes such as major adverse cardiovascular and renal events. Furthermore, it is likely that hypomagnesemia causes the release of inflammatory cytokines and C-reactive protein and promotes insulin resistance. Animal models have shown that Mg supplementation reverses vascular calcifications; thus, clinicians have focused on the potential benefits that Mg supplementation may have in humans. Recent evidence suggests that Mg reduces coronary artery calcifications and facilitates peripheral vasodilation. Mg may reduce vascular calcification by direct inhibition of the Wnt/β-catenin signaling pathway. Furthermore, Mg deficiency worsens kidney injury induced by an increased tubular load of phosphate. One important consequence of excessive tubular load of phosphate is the reduction of renal tubule expression of α-Klotho in moderate CKD. Low Mg levels worsen the reduction of Klotho induced by the tubular load of phosphate. Evidence to support clinical translation is yet insufficient, and more clinical studies are required to claim enough evidence for decision-making in daily practice. Meanwhile, it seems reasonable to prevent and treat Mg deficiency. This review aims to summarize the current understanding of Mg homeostasis, the potential mechanisms that may mediate the effect of Mg deficiency on CKD progression, CVD, and mortality.

A Higher Concentration of Dialysate Magnesium to Reduce the Frequency of Muscle Cramps: A Narrative Review

Purpose of review:

Strategies to mitigate muscle cramps are a top research priority for patients receiving hemodialysis. As hypomagnesemia is a possible risk factor for cramping, we reviewed the literature to better understand the physiology of cramping as well as the epidemiology of hypomagnesemia and muscle cramps. We also sought to review the evidence from interventional studies on the effect of oral and dialysate magnesium-based therapies on muscle cramps.

Sources of information:

Peer-reviewed articles.

Methods:

We searched for relevant articles in major bibliographic databases including MEDLINE and EMBASE. The methodological quality of interventional studies was assessed using a modified version of the Downs and Blacks criteria checklist.

Key findings:

The etiology of muscle cramps in patients receiving hemodialysis is poorly understood and there are no clear evidence-based prevention or treatment strategies. Several factors may play a role including a low concentration of serum magnesium. The prevalence of hypomagnesemia (concentration of <0.7 mmol/L) in patients receiving hemodialysis ranges from 10% to 20%. Causes of hypomagnesemia include a low dietary intake of magnesium, use of medications that inhibit magnesium absorption (eg, proton pump inhibitors), increased magnesium excretion (eg, high-dose loop diuretics), and a low concentration of dialysate magnesium. Dialysate magnesium concentrations of ≤0.5 mmol/L may be associated with a decrease in serum magnesium concentration over time. Preliminary evidence from observational and interventional studies suggests a higher dialysate magnesium concentration will raise serum magnesium concentrations and may reduce the frequency and severity of muscle cramps. However, the quality of evidence supporting this benefit is limited, and larger, multicenter clinical trials are needed to further determine if magnesium-based therapy can reduce muscle cramps in patients receiving hemodialysis. In studies conducted to date, increasing the concentration of dialysate magnesium appears to be well-tolerated and is associated with a low risk of symptomatic hypermagnesemia.

Limitations:

Few interventional studies have examined the effect of magnesium-based therapy on muscle cramps in patients receiving hemodialysis and most were nonrandomized, pre-post study designs.

High serum magnesium levels are associated with favorable prognoses in diabetic hemodialysis patients, retrospective observational study

Background

Recent studies have found hypomagnesemia is linked to a heightened risk of cardiovascular events and mortality in hemodialysis (HD) patients; however, the level of serum magnesium (s-Mg) necessary for promoting overall health in these patients and the effects of s-Mg in diabetes HD patients remains to be clarified.

Methods

HD outpatients (n = 148 under, age ≤ 70 y) were followed over a 6-y period. They were divided into four groups according to their average s-Mg during the first year (L; low level, H; high level) and if they had DM or not (non-DM). The endpoint was mortality and hospitalization for decline of Activities of Daily Living (death/hospitalization). A receiver operating characteristics curve was used in diagnostic tests to identify s-Mg associated with this endpoint. Kaplan–Meier, log-rank test, and a Cox proportional hazards model were used to evaluate prognoses. Fisher's exact test and multiple regressions examined the causes of the endpoints between the four groups and the factors predictive of s-Mg.

Results

s-Mg at 2.7 mg/dL was associated with death/hospitalization. The 5-y survival rate was 38.1%, 86.7%, 73.2% and 87.5%, in the DM/Mg(L), DM/Mg(H), non-DM/Mg(L) and non-DM/Mg(H) groups, respectively (P < 0.001). The Cox proportional hazards model showed significantly lower risk in other groups compared with that in the DM/Mg(L) group [DM/Mg(H); hazard ratio (HR): 0.22, 95% confidence interval (CI): 0.05–0.97, P = 0.046, non-DM/Mg(L); HR: 0.32, 95% CI: 0.15–0.68, P = 0.003, non-DM/Mg(H); HR: 0.17, 95% CI: 0.06–0.44, P < 0.001]. The frequency of the different causes of the endpoints for each group was not significant; s-Mg only associated with age in the DM group.

Conclusions

s-Mg greater than 2.7 mg/dL associated with a favorable prognosis in HD patients with DM, suggesting that s-Mg is a factor independent of diabetes.

Quantitative Association Between Serum/Dietary Magnesium and Cardiovascular Disease/Coronary Heart Disease Risk: A Dose-Response Meta-analysis of Prospective Cohort Studies

BACKGROUND

The quantitative association between serum/dietary magnesium and cardiovascular disease (CVD) remains unclear. We conducted a dose-response meta-analysis to evaluate the quantitative association between serum/dietary magnesium and CVD, including coronary heart disease (CHD).

METHODS

PubMed, China National Knowledge Infrastructure, and Web of Science were searched for publications. STATA 12.0 was used to analyze data. We used the random-effects model to reduce heterogeneity.

RESULTS

Eighteen prospective cohort studies with 544,581 participants and 22,658 CVD cases were included. The follow-up duration was 1-28 years. The pooled relative risk (RR) of CVD for the relatively normal versus lowest serum and dietary magnesium level was 0.64 {[95% confidence interval (CI): 0.51-0.80] and 0.90 [95% CI: 0.84-0.96]}. The pooled RR of CHD for the relatively normal versus lowest serum and dietary magnesium level was 0.70 (95% CI: 0.57-0.85) and 0.86 (95% CI: 0.77-0.94). We noted a significant association between increasing serum magnesium levels (per 0.1-mg/dL increase) and risk of CVD (RR: 0.93, 95% CI: 0.88-0.97) and CHD (RR: 0.90, 95% CI: 0.84-0.96) and between dietary magnesium levels (per 100-mg/d increase) and risk of CVD (RR: 0.90, 95% CI: 0.83-0.96) and CHD (RR: 0.92, 95% CI: 0.82-0.98). Serum/dietary Mg level comparisons presented a 7%-10% decrease in CVD/CHD risk. The dose-response meta-analyses showed linear relationships between serum magnesium and CVD (Pnonlinearity = 0.833) or CHD (Pnonlinearity = 0.193) and dietary magnesium and CVD (Pnonlinearity = 0.463) or CHD (Pnonlinearity = 0.440).

CONCLUSIONS

Increasing dietary magnesium or serum magnesium level is linearly and inversely associated with the risk of total CVD and CHD events.

Magnesium and calciprotein particles in vascular calcification: the good cop and the bad cop

PURPOSE OF REVIEW

Vascular calcification is a major contributor to increased cardiovascular mortality in chronic kidney disease (CKD). Recently, calciprotein particles (CPP) were identified to drive the calcification process. CPP may explain the effects of high phosphate on vascular calcification. Magnesium is a promising novel therapeutic approach to halt vascular calcification, because it inhibits CPP maturation and is associated with reduced cardiovascular mortality in CKD. We aim to examine the current evidence for the role of CPP in the calcification process and to explain how magnesium prevents calcification.

RECENT FINDINGS

A recent meta-analysis concluded that reducing high phosphate levels in CKD patients does not associate with lowering cardiovascular mortality. Inhibition of CPP formation prevents phosphate-induced calcification in vitro. Consequently, delaying CPP formation and maturation may be a clinical approach to reduce calcification. Magnesium inhibits CPP maturation and vascular calcification. Clinical pilot studies suggest that magnesium is a promising intervention strategy against calcification in CKD patients.

SUMMARY

CPP induce vascular calcification and are modulated by serum phosphate and magnesium concentrations. Magnesium is a strong inhibitor of CPP maturation and therefore, a promising therapeutic approach to reduce vascular calcification in CKD. Currently, several studies are being performed to determine the clinical outcomes of magnesium supplementation in CKD.

Altered Mineral Metabolism and Disequilibrium Between Calcification Promoters and Inhibitors in Chronic Hemodialysis Patients

Patients undergoing long-term hemodialysis (HD) are known to have abnormal blood concentrations of antioxidant minerals; concurrent oxidative stress can contribute to increased vascular calcification. This study aims to evaluate the associations between circulating antioxidant minerals and clinical biomarkers of vascular calcification in HD patients. Blood biochemical parameters, antioxidant minerals (selenium (Se), zinc (Zn), copper (Cu), and magnesium (Mg)), and several promoters and inhibitors of calcification (matrix Gla protein (MGP), fibroblast growth factor-23 (FGF-23), matrix metalloproteinases (MMP-2 and -9), and tissue inhibitors of metalloproteinase (TIMP-1 and -2)) were determined in HD patients (n = 62) and age- and sex-matched healthy individuals (n = 30). Compared with healthy subjects, HD patients had significantly lower plasma concentrations of Se and Zn, increased Cu and Mg, and higher levels of oxidative stress and inflammatory markers (Cu/Zn ratios, malondialdehyde (MDA), advanced glycation end products (AGEs), and C-reactive protein (CRP)). We observed that HD patients had significantly lower concentrations of MGP and higher levels of FGF-23, MMP-2 and -9, TIMP-1 and -2, and MMP-2/TIMP-2 and MMP-9/TIMP-1 ratios. We also observed significant relationships between the concentrations of these minerals and calcification biomarkers in HD patients. These results suggest that changes in the homeostasis of antioxidant minerals (Se, Zn, Cu, and Mg) may contribute to the effects of oxidative stress and inflammatory status, thereby participating in the mechanism for accelerated vascular calcification in patients undergoing long-term HD.

Hypomagnesemia and Short-Term Mortality in Elderly Maintenance Hemodialysis Patients

Background

The relationship between magnesium and mortality in hemodialysis patients has been evaluated in several prospective studies, but few have assessed the risk of all-cause mortality in elderly hemodialysis patients. The aim of this study was to evaluate the association between magnesium levels and the risk of cardiovascular and overall mortality in elderly maintenance hemodialysis patients.

Methods

This was a retrospective study, and patients undergoing maintenance hemodialysis were screened for eligibility at a single dialysis center between July and December 2016. Patients were divided into two groups based on their magnesium levels: a low magnesium level group and a high magnesium level group. Associations between magnesium level and risk of cardiovascular and all-cause mortality were analyzed with a Cox proportional hazards regression model.

Results

In total, 413 patients were included with a median follow-up period of 12 months. We found that compared to patients with high magnesium levels, those with low magnesium levels had significantly lower levels of hemoglobin, urea, creatinine, uric acid, phosphate, potassium, chloride, albumin, and spKt/V (p < 0.05 for each parameter). There was a strong correlation between the baseline mean serum magnesium concentration 1 year prior and the concentration 1 year later (r² = 0.519, p < 0.001). After adjustment for confounding factors, multivariate Cox proportional hazards analysis showed hypomagnesemia to be an independent predictor of all-cause and cardiovascular mortality in chronic hemodialysis patients. Furthermore, subgroup analysis was performed, revealing that serum magnesium levels were still strongly associated with all-cause mortality and cardiovascular mortality in patients older than 60 years, with HR values of 0.020 (95% CI 0.001-0.415) and 0.010 (95% CI 0.000-0.491), respectively. In addition, there were still significant associations between the serum magnesium level and all-cause mortality and cardiovascular mortality in elderly dialysis patients at the 6-month follow-up visit.

Conclusion

Our study indicates that lower serum magnesium levels are strongly associated with cardiovascular and all-cause mortality in maintenance hemodialysis patients, especially in the short term and in those who are elderly. Factors affecting serum magnesium concentrations in hemodialysis patients should be investigated, and correcting hypomagnesemia may benefit elderly hemodialysis patients.

Association of serum magnesium with all-cause mortality in patients with and without chronic kidney disease in the Dallas Heart Study

Background

Low serum magnesium (SMg) has been linked to increased mortality and cardiovascular disease (CVD) in the general population. We examined whether this association is similar in participants with versus without prevalent chronic kidney disease (CKD) in the multiethnic Dallas Heart Study (DHS) cohort.

Methods

SMg was analyzed as a continuous variable and divided into tertiles. Study outcomes were all-cause death, cardiovascular (CV) death or event, and CVD surrogate markers, evaluated using multivariable Cox regression models adjusted for demographics, comorbidity, anthropometric and biochemical parameters including albumin, phosphorus and parathyroid hormone, and diuretic use. Median follow-up was 12.3 years (11.9-12.8, 25th percentile-75th percentile).

Results

Among 3551 participants, 306 (8.6%) had prevalent CKD. Mean SMg was 2.08 ± 0.19 mg/dL (0.85 ± 0.08 mM, mean ± SD) in the CKD and 2.07 ± 0.18 mg/dL (0.85 ± 0.07 mM) in the non-CKD subgroups. During the follow-up period, 329 all-cause deaths and 306 CV deaths or events occurred. In a fully adjusted model, every 0.2 mg/dL decrease in SMg was associated with ∼20-40% increased hazard for all-cause death in both CKD and non-CKD subgroups. In CKD participants, the lowest SMg tertile was also independently associated with all-cause death (adjusted hazard ratio 2.31; 95% confidence interval 1.23-4.36 versus 1.15; 0.55-2.41; for low versus high tertile, respectively).

Conclusions

Low SMg levels (1.4-1.9 mg/dL; 0.58-0.78 mM) were independently associated with all-cause death in patients with prevalent CKD in the DHS cohort. Randomized clinical trials are important to determine whether Mg supplementation affects survival in CKD patients.

Modifying Phosphate Toxicity in Chronic Kidney Disease

Phosphate toxicity is a well-established phenomenon, especially in chronic kidney disease (CKD), where hyperphosphatemia is a frequent occurrence when CKD is advanced. Many therapeutic efforts are targeted at phosphate, and comprise dietary intervention, modifying dialysis schemes, treating uncontrolled hyperparathyroidism and importantly, phosphate binder therapy. Despite all these interventions, hyperphosphatemia persists in many, and its pathological influence is ongoing. In nephrological care, a somewhat neglected aspect of treatment-when attempts fail to lower exposure to a toxin like phosphate-is to explore the possibility of "anti-dotes". Indeed, quite a long list of factors modify, or are mediators of phosphate toxicity. Addressing these, especially when phosphate itself cannot be sufficiently controlled, may provide additional protection. In this narrative overview, several factors are discussed that may qualify as either such a modifier or mediator, that can be influenced by other means than simply lowering phosphate exposure. A wider scope when targeting phosphate-induced comorbidity in CKD, in particular cardiovascular disease, may alleviate the burden of disease that is the consequence of this potentially toxic mineral in CKD.

Sudden Cardiac Death in End-Stage Renal Disease

The challenge presented by sudden cardiac death in dialysis patients is to better define risk factors and delineate multiple etiologies. Only then can therapy be tailored to the highest risk patients and the incidence of sudden cardiac death be reduced. This article details the many possible etiologies and presents a brief overview of more recent research that may in the future prove of great benefit in improving the mortality of our patients with end-stage renal disease.

Inadvertently high dialysate magnesium causing weakness and nausea in hemodialysis patients

As maintenance hemodialysis patients are exposed to large quantities of dialysis water, any contamination of it might be reflected in plasma levels. We present a series of cases due to such a contamination. Six maintenance hemodialysis patients dialyzing at the same peripheral hemodialysis facility presented to us over a short period of time with symptoms mimicking inadequate dialysis. Their blood urea and creatinine levels were not very high, but all the patients had hypermagnesemia [serum Mg levels = 1.8 (±0.3) mmol/L]. Except for one patient who had cardiac arrest at presentation, all patients improved after undergoing hemodialysis at our center [serum Mg at discharge = 0.86 (±0.01) mmol/L]. The origin of hypermagnesemia was traced to dialysis water contamination with magnesium due to inadequate maintenance of the water treatment system. Corrective measures improved the quality of water, and no further cases were reported from that center. Proper maintenance and periodic checks of the quality of water are central to the outcomes of maintenance hemodialysis patients.

The relationship between serum magnesium levels and mortality in non-diabetic hemodialysis patients: A 10-year follow-up study

Introduction Recently, although there are many reports showing that serum magnesium concentration is a predictor of mortality in dialysis patients, the observation periods of those reports were of short duration, typically around 12 months. Thus, we investigated this relationship over a longer follow-up period. Methods This retrospective, observational study included a total of 83 non-diabetic hemodialysis patients. The follow-up period was 120 months. Patients were divided into two groups, those with serum magnesium ≥2.5 mg/dL (Mg ≥2.5 mg/dL group) and serum magnesium <2.5 mg/dL (Mg <2.5 mg/dL group), and Kaplan-Meier analysis and Cox proportional hazards analysis were conducted. In addition to the above analysis, single and multiple regression analysis were performed at baseline to reveal the relationship between serum magnesium and clinical parameters. Findings During the follow-up period, 31 out of 83 patients died. Kaplan-Meier analysis showed a significantly higher incidence of death in the Mg <2.5 mg/dL group (log-rank test 4.951, P = 0.026). Multivariate Cox proportional hazards analysis showed a 62% decreased risk of mortality in the Mg ≥2.5 mg/dL group compared to the Mg <2.5 mg/dL group after adjustment for several confounding factors. Simple correlation coefficient analysis showed positive correlations of serum magnesium levels with serum creatinine, phosphorus, high-density lipoprotein, ankle-brachial index and KT/V, and a negative correlation with age. Multiple linear regression analysis showed that the ankle-brachial index was the only parameter that had a positive and significant correlation with the serum magnesium level. Conclusion Our study demonstrated that higher serum magnesium levels were associated with improved survival in non-diabetic hemodialysis patients.

Hypomagnesemia is not an independent risk factor for mortality in Japanese maintenance hemodialysis patients

PURPOSE

It is unclear whether hypomagnesemia is an independent risk factor or innocent bystander for mortality in maintenance hemodialysis (MHD) patients. Thus, we studied associations between hypomagnesemia and all-cause as well as cardiovascular (CV) mortality in MHD patients.

METHODS

Baseline clinical characteristics and coronary artery calcium score (CACS) of 353 Japanese MHD patients were reviewed. Three-year survival rate and mortality risk factors were assessed.

RESULTS

Median (interquartile range) age, dialysis vintage, serum magnesium (Mg), serum albumin and CACS of the subjects were 68 (60-78) years, 75 (32-151) months, 2.4 (2.2-2.7) mg/dl, 3.6 (3.3-3.8) g/dl, and 1181 (278-3190), respectively. During the 3-year period, 91 patients died. Kaplan-Meier overall 3-year survival rates were 59.0% in in patients with Mg < 2.4 mg/dl (n = 136) and 82.3% in patients with Mg ≥ 2.4 mg/dl (n = 217), (P < 0.0001). In Cox regression models not incorporating serum albumin, Mg < 2.4 mg/dl was significantly associated with 3-year all-cause death, independent of age, dialysis vintage, average ultrafiltration, Log (CACS + 1), warfarin use, serum potassium, high-sensitivity C-reactive protein (hsCRP), phosphate, uric acid, and intact parathyroid hormone [Hazard ratio (HR) 95% confidence interval (CI): 2.82 (1.31-6.29), P = 0.0078], and CV death, independent of age, dialysis vintage, Log (CACS + 1), warfarin use, serum hsCRP, and uric acid [HR (95% CI): 4.47 (1.45-16.76), P = 0.0086]. Nevertheless, associations of Mg < 2.4 mg/dl with all-cause and CV mortality were all absent in models that included serum albumin.

CONCLUSIONS

Hypomagnesemia is not an independent risk factor for mortality but is associated with malnutrition in MHD patients.

Serum magnesium, mortality, and cardiovascular disease in chronic kidney disease and end-stage renal disease patients: a systematic review and meta-analysis

BACKGROUND

Previous studies reported that magnesium deficiency was associated with vascular calcifications, atherosclerosis and cardiovascular disease, which might play an independent pathogenic role in chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients. However, the results of these studies were somewhat underpowered and inconclusive.

METHODS

Literature was identified by searching PubMed, EMBASE, Web of Science and the Cochrane Central Register of Controlled Trials (CENTRAL). We included studies that investigated the association between serum magnesium with mortality risk in CKD and ESRD patients. Unadjusted and adjusted hazard ratios (HRs) with 95% confidence intervals (95% CIs) were pooled.

RESULTS

Twenty studies involving 200,934 participants were included, and the results showed that there was a strong association between hypomagnesemia and the risk of all-cause mortality in patients with CKD and ESRD (HR 1.32; 95% CI 1.19-1.47; p < 0.00001) (hypomagnesemia vs. normal magnesium or hypermagnesemia) after multivariable adjusted. On the contrary, hypermagnesemia was inversely associated with all-cause mortality in patients with CKD and ESRD (HR 0.86; 95% CI 0.79-0.94; p = 0.001) (per unit increase). Moreover, a significant association between hypermagnesemia and decreased risk of cardiovascular mortality was observed (HR 0.71; 95% CI 053-0.97, p = 0.03) in the adjusted model. In addition, subgroup analysis found that hypomagnesemia was strongly associated with increased all-cause mortality in hemodialysis patients (HR 1.29; 95% CI 1.12-1.50; p = 0.0005) (hypomagnesemia vs. normal magnesium or hypermagnesemia).

CONCLUSIONS

Our results indicate that hypomagnesemia is significantly associated with cardiovascular and all-cause mortality in patients with CKD and ESRD. Further studies evaluating benefits of magnesium correction in CKD and dialysis patients with hypomagnesemia should be performed.

Relationship between dialytic parameters and reviewer confirmed arrhythmias in hemodialysis patients in the monitoring in dialysis study

Background

Hemodialysis patients have high rates of sudden death, but relationships between serum electrolytes, the dialysis prescription, and intra-dialytic shifts in fluid and electrolyte with arrhythmia are uncertain.

Methods

We analyzed sixty-six hemodialysis patients who underwent loop recorder implantation with continuous electrocardiographic monitoring, weekly to bi-weekly testing of pre- and post-dialysis electrolytes, and detailed capture of dialysis prescription and flow sheet data for 6 months. The incidence rate ratio (IRR) of reviewer confirmed arrhythmias (RCA) during dialysis through 8 h after dialysis and associations with serum chemistries and dialytic parameters were assessed using adjusted, negative-binomial regression.

Results

Among 66 individuals with a mean age of 56 years, 12,480 events were detected in 64 (97%) patients. RCA nadired 12–24 h after dialysis and increased during the final 12 h of the inter-dialytic interval through the first 8 h after dialysis. Higher pre-dialysis serum magnesium concentration was associated with lower incidence rate ratio for arrythmia (IRR per 1 mg/dL increase 0.49, 95% CI; 0.25, 0.94), as was dialysate calcium concentration > 2.5 mEq/L vs. 2.5 mEq/L (IRR 0.52, 95% CI: 0.39, 0.70). Neither intradialytic serum potassium nor weight change were significantly associated with RCA rate. However, there was effect modification such that arrhythmia rate was maximal with concurrently high intradialytic volume and potassium removal (P_interaction = 0.01).

Conclusions

Intra and post-dialytic arrhythmias are common in hemodialysis. Additional studies designed to further elucidate whether modification of the serum magnesium concentration, dialysate calcium concentration, and the extent of intradialytic potassium and fluid removal reduces the risk of per-dialytic arrhythmia are warranted.

Trial registration

Clinicaltrials.gov NCT01779856. Prospectively registered on January 22, 2013.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1212-6) contains supplementary material, which is available to authorized users.

Low serum magnesium is associated with faster decline in kidney function: the Dallas Heart Study experience

Hypomagnesemia associates with inflammation and risk of diabetes and hypertension, which may contribute to kidney function decline. We hypothesized that low serum magnesium (SMg) levels independently associate with a significant decline in estimated glomerular filtration rate (eGFR). We analyzed SMg levels in 2056 participants from the Dallas Heart Study, a longitudinal, population-based, multiethnic, cohort study involving residents of Dallas County, Texas, USA. The primary study outcome was the change in eGFR using multivariable linear regression models adjusted for demographics, anthropometric and biochemical parameters, medications, C reactive protein levels, prevalent hypertension and diabetes. During a median follow-up of 7.0 years (25th, 75th percentile: 6.5, 7.6), the median decrease in eGFR was -0.71 (25th, 75th percentile: -2.43, +0.68) mL/min/1.73 m² per year in the entire cohort. In a fully adjusted model, the lowest SMg quintile (≤1.9 mg/dL or ≤0.8 mM) was associated with a -0.50 mL/min/1.73 m² per year drop in eGFR (95% CI -0.95 to -0.05; p=0.028) compared with the highest SMg quintile (≥2.3 mg/dL or ≥1.0 mM). Every 0.2 mg/dL (0.08 mM) decrease in SMg was associated with an eGFR decline of -0.23 mL/min/1.73 m² per year (95% CI -0.38 to -0.08; p=0.003), a decline that was more pronounced in participants with prevalent diabetes compared with patients without diabetes (-0.51 vs -0.18 mL/min/1.73 m² per year, respectively). In conclusion, low SMg was independently associated with eGFR decline. Further studies are needed to determine whether Mg repletion can ameliorate inflammation, lower blood pressure and serum glucose and ultimately prevent or retard kidney function decline.

Magnesium: A Magic Bullet for Cardiovascular Disease in Chronic Kidney Disease?

Magnesium is essential for many physiological functions in the human body. Its homeostasis involves dietary intake, absorption, uptake and release from bone, swifts between the intra- and extracellular compartment, and renal excretion. Renal excretion is mainly responsible for regulation of magnesium balance. In chronic kidney disease (CKD), for a long time the general policy has been limiting magnesium intake. However, this may not be appropriate for many patients. The reference ranges for magnesium are not necessarily optimal concentrations, and risks for insufficient magnesium intake exist in patients with CKD. In recent years, many observational studies have shown that higher (in the high range of “normal” or slightly above) magnesium concentrations are associated with better survival in CKD cohorts. This review gives an overview of epidemiological associations between magnesium and overall and cardiovascular survival in patients with CKD. In addition, potential mechanisms explaining the protective role of magnesium in clinical cardiovascular outcomes are described by reviewing evidence from in vitro studies, animal studies, and human intervention studies with non-clinical endpoints. This includes the role of magnesium in cardiac arrhythmia, heart failure, arterial calcification, and endothelial dysfunction. Possible future implications will be addressed, which will need prospective clinical trials with relevant clinical endpoints before these can be adopted in clinical practice.

Clearance of Magnesium in Peritoneal Dialysis Patients: A Single-Center Study

OBJECTIVE

This retrospective study aimed to investigate the clearance of magnesium (Mg) in peritoneal dialysis (PD) patients and its influencing factors.

METHODS

The demographic information, clinical characteristics and laboratory data of the patients were collected. According to the corrected serum Mg (cS-Mg) concentration, patients were divided into 3 groups including hypomagnesemia (Mg2+ < 0.77 mmol/L, group A), normal serum Mg concentration (0.77 mmol/L ≤ Mg2+ ≤1.03 mmol/L, group B), and hypermagnesemia (Mg2+ > 1.03 mmo/L, group C).

RESULTS

One hundred and fifteen patients were enrolled, and their mean 24 h-peritoneal Mg clearance was 39.75 ± 17.42 mg. The mean normalized peritoneal Mg clearance rate was 1.82 ± 0.82 L/day/1.73 m2. Twenty-four-hour peritoneal Mg clearance of group A was significantly lower than that of group C (p < 0.05). Bivariate correlation analysis showed that cS-Mg was positively correlated with peritoneal dialysate Mg concentration (p < 0.01). cS-Mg was negatively correlated with the normalized peritoneal Mg clearance rate (p < 0.05). The normalized peritoneal Mg clearance rate was positively correlated with prealbumin (p < 0.05), daily peritoneal protein loss (p < 0.01) and the normalized PD-creatinine clearance rate (p < 0.01). The normalized peritoneal Mg clearance rate was also negatively correlated with the normalized renal-creatinine clearance rate (p < 0.01). Furthermore, cS-Mg of patients with continuous ambulatory PD (CAPD) was significantly lower than that of patients with daytime ambulatory PD (DAPD, p < 0.01). The normalized peritoneal Mg clearance rate of patients with CAPD was significantly higher than that of patients with DAPD (p < 0.01). Moreover, among the patients with different peritoneal transport characteristics of peritoneal equilibration test, the normalized peritoneal Mg clearance rate of high average transport patients was significantly higher than that in those with low transport, low average transport and high transport (p < 0.05).

CONCLUSIONS

Serum Mg could be partly cleared by PD. The peritoneal Mg clearance was positively related with serum Mg concentration, which was concentration-dependent. Peritoneal Mg clearance was negatively correlated with the residual renal function, while being positively correlated with the nutritional status and daily peritoneal protein loss. Peritoneal Mg clearance was higher in patients with high transport characteristics or CAPD.

Routine hemodialysis induces a decline in plasma magnesium concentration in most patients: a prospective observational cohort study

In hemodialysis patients, lower plasma magnesium (Mg) concentrations are associated with a higher overall and cardiovascular mortality. The optimal concentration appears to be above the reference range for the healthy population. Plasma Mg is not routinely measured after hemodialysis. Aim of this study was to determine the effect of routine hemodialysis on plasma Mg. Plasma Mg was measured in duplicate before (Mgpre) and after (Mgpost) dialysis in 6 consecutive hemodialysis sessions of 34 patients using a fixed 0.50 mmol/L dialysate Mg concentration. Mean Mgpre was 0.88 mmol/L (±0.14) and mean Mgpost was statistically significantly lower: mean intra-dialytic decline 0.10 mmol/L (95%-CI 0.06-0.13). A 0.10 mmol/L higher Mgpre was associated with a 0.03 mmol/L higher Mgpost (95%-CI 0.024-0.037). At a Mgpre of 0.74 mmol/L, Mgpost equalled Mgpre. There was an intra-dialytic decline of plasma Mg at higher Mgpre values and an increase at lower Mgpre values. In conclusion, in the majority of the hemodialysis patients, Mgpre concentrations are in the reference range of the healthy population, which may be too low for hemodialysis patients. Routine hemodialysis with the widely used 0.50 mmol/L dialysate Mg concentration, further declines magnesium in the majority of patients. Current dialysate Mg concentrations may be too low.

Proton pump inhibitor as an independent factor of progression of abdominal aortic calcification in patients on maintenance hemodialysis

BACKGROUNDS

Proton pump inhibitors (PPIs) can be associated with vascular calcification in patients undergoing dialysis through hypomagnesemia. However, only few studies have demonstrated the influence of PPIs on vascular calcification in patients on maintenance hemodialysis (HD). This study aimed to investigate whether the use of PPIs accelerates vascular calcification in patients on HD.

MATERIALS AND METHODS

We retrospectively evaluated 200 HD patients who underwent regular blood tests and computed tomography (CT) between 2016 and 2017. The abdominal aortic calcification index (ACI) was measured using abdominal CT. The difference in the ACI values between 2016 and 2017 was evaluated as ΔACI. Patients were divided into PPI and non-PPI groups, and variables, such as patient background, medication, laboratory data, and ΔACI were compared. Factors independently associated with higher ΔACI progression (≥ third tertile value of ΔACI in this study) were determined using multivariate logistic regression analysis.

RESULTS

The PPI and non-PPI groups had 112 (56%) and 88 (44%) patients, respectively. Median and third tertile value of ΔACIs were 4.2% and 5.8%, respectively. Serum magnesium was significantly lower in the PPI (2.1 mg/dL) than in the non-PPI (2.3 mg/dL) group (P <0.001). Median ΔACI was significantly higher in the PPI (5.0%) than in the non-PPI (3.8%) group (P = 0.009). A total of 77 (39%) patients had a higher ΔACI. Multivariate analysis revealed that PPIs (odds ratio = 2.23; 95% confidence interval = 1.11-4.49), annual mean calcium phosphorus product, ACI in 2016, baseline serum magnesium levels, and HD vintage were independent factors associated with higher ΔACI progression after adjusting for confounders.

CONCLUSION

PPI use may accelerate vascular calcification in patients on HD. Further studies are necessary to elucidate their influence on vascular calcification.

Mechanisms and Regulation of Intestinal Phosphate Absorption

States of hypo- and hyperphosphatemia have deleterious consequences including rickets/osteomalacia and renal/cardiovascular disease, respectively. Therefore, the maintenance of appropriate plasma levels of phosphate is an essential requirement for health. This control is executed by the collaborative action of intestine and kidney whose capacities to (re)absorb phosphate are regulated by a number of hormonal and metabolic factors, among them parathyroid hormone, fibroblast growth factor 23, 1,25(OH)₂ vitamin D₃ , and dietary phosphate. The molecular mechanisms responsible for the transepithelial transport of phosphate across enterocytes are only partially understood. Indeed, whereas renal reabsorption entirely relies on well-characterized active transport mechanisms of phosphate across the renal proximal epithelia, intestinal absorption proceeds via active and passive mechanisms, with the molecular identity of the passive component still unknown. The active absorption of phosphate depends mostly on the activity and expression of the sodium-dependent phosphate cotransporter NaPi-IIb (SLC34A2), which is highly regulated by many of the factors, mentioned earlier. Physiologically, the contribution of NaPi-IIb to the maintenance of phosphate balance appears to be mostly relevant during periods of low phosphate availability. Therefore, its role in individuals living in industrialized societies with high phosphate intake is probably less relevant. Importantly, small increases in plasma phosphate, even within normal range, associate with higher risk of cardiovascular disease. Therefore, therapeutic approaches to treat hyperphosphatemia, including dietary phosphate restriction and phosphate binders, aim at reducing intestinal absorption. Here we review the current state of research in the field. © 2017 American Physiological Society. Compr Physiol 8:1065-1090, 2018.

Deleting Death and Dialysis: Conservative Care of Cardio-Vascular Risk and Kidney Function Loss in Chronic Kidney Disease (CKD)

The uremic syndrome, which is the clinical expression of chronic kidney disease (CKD), is a complex amalgam of accelerated aging and organ dysfunctions, whereby cardio-vascular disease plays a capital role. In this narrative review, we offer a summary of the current conservative (medical) treatment options for cardio-vascular and overall morbidity and mortality risk in CKD. Since the progression of CKD is also associated with a higher cardio-vascular risk, we summarize the interventions that may prevent the progression of CKD as well. We pay attention to established therapies, as well as to novel promising options. Approaches that have been considered are not limited to pharmacological approaches but take into account lifestyle measures and diet as well. We took as many randomized controlled hard endpoint outcome trials as possible into account, although observational studies and post hoc analyses were included where appropriate. We also considered health economic aspects. Based on this information, we constructed comprehensive tables summarizing the available therapeutic options and the number and kind of studies (controlled or not, contradictory outcomes or not) with regard to each approach. Our review underscores the scarcity of well-designed large controlled trials in CKD. Nevertheless, based on the controlled and observational data, a therapeutic algorithm can be developed for this complex and multifactorial condition. It is likely that interventions should be aimed at targeting several modifiable factors simultaneously.

Proteinuria-associated renal magnesium wasting leads to hypomagnesemia: a common electrolyte abnormality in chronic kidney disease

Background

Hypomagnesemia (Hypo-Mg) predicts mortality and chronic kidney disease (CKD) progression. However, in CKD, its prevalence, kidney-intrinsic risk factors, and the effectiveness of oral magnesium (Mg) therapy on serum Mg levels is uncertain.

Methods

In a cross-sectional study enrolling pre-dialysis outpatients with CKD, the prevalence of electrolyte abnormalities (Mg, sodium, potassium, calcium and phosphorus) was compared. In an open-label randomized controlled trial (RCT), we randomly assigned CKD patients to either the magnesium oxide (MgO) or control arm. The outcome was serum Mg levels at 1 year.

Results

In 5126 patients, Hypo-Mg was the most common electrolyte abnormality (14.7%) with similar prevalence across stages of CKD. Positive proteinuria was a risk factor of Hypo-Mg (odds ratio 2.2; 95% confidence interval 1.2–4.0). However, stratifying the analyses by diabetes mellitus (DM), it was not significant in DM (Pinteraction = 0.04). We enrolled 114 patients in the RCT. Baseline analyses showed that higher proteinuria was associated with higher fractional excretion of Mg. This relationship between proteinuria and renal Mg wasting was mediated by urinary tubular markers in mediation analyses. In the MgO arm, higher proteinuria or tubular markers predicted a significantly lower 1-year increase in serum Mg. In patients with a urinary protein-to-creatinine ratio (uPCR) <0.3 g/gCre, serum Mg at 1 year was 2.4 and 2.0 mg/dL in the MgO and control arms, respectively (P < 0.001), with no significant between-group difference in patients whose uPCR was ≥0.3 g/gCre (Pinteraction=0.001).

Conclusions

Proteinuria leads to renal Mg wasting through tubular injuries, which explains the high prevalence of Hypo-Mg in CKD.

Anion Gap as a Determinant of Ionized Fraction of Divalent Cations in Hemodialysis Patients

BACKGROUND AND OBJECTIVES

Circulating levels of anions that bind to magnesium and calcium are often altered in patients with CKD. However, it is unknown how these alterations affect the ionized fraction of magnesium and calcium.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This cross-sectional study involved patients on maintenance hemodialysis and patients not on dialysis who visited the outpatient department of nephrology. We collected whole-blood samples to measure ionized magnesium and calcium concentrations. Adjusted anion gap was calculated as an integrative index of unmeasured anions.

RESULTS

A total of 118 patients on hemodialysis and 112 patients not on dialysis were included. Although the prevalence of hypermagnesemia defined by total magnesium was much higher in patients on hemodialysis than in patients not on dialysis (69% versus 12%; P<0.001), the prevalence of hypermagnesemia defined by ionized magnesium did not differ significantly (13% versus 18%; P=0.28). Among patients on hemodialysis with high total magnesium, 83% had normal or low ionized magnesium. Consequently, the mean ionized fraction of magnesium in patients on hemodialysis was significantly lower than that in patients not on dialysis (51% versus 63%; P<0.001). Similarly, the mean ionized fraction of calcium in patients on hemodialysis was lower than that in patients not on dialysis (55% versus 56%; P<0.001). In patients on hemodialysis who had a higher adjusted anion gap than patients not on dialysis (mean [SD]: 14.1 [2.2] versus 5.1 [3.1]), the ionized fractions of magnesium and calcium were inversely associated with the adjusted anion gap. Furthermore, the anion gap significantly improved predictions of ionized magnesium and calcium in patients on hemodialysis.

CONCLUSIONS

Anions that accumulate in patients on hemodialysis contribute to the lower ionized fraction of magnesium and calcium. Equations that incorporate the anion gap provide better predictions of ionized magnesium and calcium in patients on hemodialysis.

Magnesium prevents vascular calcification in vitro by inhibition of hydroxyapatite crystal formation

Magnesium has been shown to effectively prevent vascular calcification associated with chronic kidney disease. Magnesium has been hypothesized to prevent the upregulation of osteoblastic genes that potentially drives calcification. However, extracellular effects of magnesium on hydroxyapatite formation are largely neglected. This study investigated the effects of magnesium on intracellular changes associated with transdifferentiation and extracellular crystal formation. Bovine vascular smooth muscle cells were calcified using β-glycerophosphate. Transcriptional analysis, alkaline phosphatase activity and detection of apoptosis were used to identify transdifferentiation. Using X-ray diffraction and energy dispersive spectroscopy extracellular crystal composition was investigated. Magnesium prevented calcification in vascular smooth muscle cells. β-glycerophosphate increased expression of osteopontin but no other genes related to calcification. Alkaline phosphatase activity was stable and apoptosis was only detected after calcification independent of magnesium. Blocking of the magnesium channel TRPM7 using 2-APB did not abrogate the protective effects of magnesium. Magnesium prevented the formation of hydroxyapatite, which formed extensively during β-glycerophosphate treatment. Magnesium reduced calcium and phosphate fractions of 68% and 41% extracellular crystals, respectively, without affecting the fraction of magnesium. This study demonstrates that magnesium inhibits hydroxyapatite formation in the extracellular space, thereby preventing calcification of vascular smooth muscle cells.

Mortality reduction by post-dilution online-haemodiafiltration: a cause-specific analysis

Background

From an individual participant data (IPD) meta-analysis from four randomized controlled trials comparing haemodialysis (HD) with post-dilution online-haemodiafiltration (ol-HDF), previously it appeared that HDF decreases all-cause mortality by 14% (95% confidence interval 25; 1) and fatal cardiovascular disease (CVD) by 23% (39; 3). Significant differences were not found for fatal infections and sudden death. So far, it is unclear, however, whether the reduced mortality risk of HDF is only due to a decrease in CVD events and if so, which CVD in particular is prevented, if compared with HD.

Methods

The IPD base was used for the present study. Hazard ratios and 95% confidence intervals for cause-specific mortality overall and in thirds of the convection volume were calculated using the Cox proportional hazard regression models. Annualized mortality and numbers needed to treat (NNT) were calculated as well.

Results

Besides 554 patients dying from CVD, fatal infections and sudden death, 215 participants died from 'other causes', such as withdrawal from treatment and malignancies. In this group, the mortality risk was comparable between HD and ol-HDF patients, both overall and in thirds of the convection volume. Subdivision of CVD mortality in fatal cardiac, non-cardiac and unclassified CVD showed that ol-HDF was only associated with a lower risk of cardiac casualties [0.64 (0.61; 0.90)]. Annual mortality rates also suggest that the reduction in CVD death is mainly due to a decrease in cardiac fatalities, including both ischaemic heart disease and congestion. Overall, 32 and 75 patients, respectively, need to be treated by high-volume HDF (HV-HDF) to prevent one all-cause and one CVD death, respectively, per year.

Conclusion

The beneficial effect of ol-HDF on all-cause and CVD mortality appears to be mainly due to a reduction in fatal cardiac events, including ischaemic heart disease as well as congestion. In HV-HDF, the NNT to prevent one CVD death is 75 per year.

Dialysate Potassium, Dialysate Magnesium, and Hemodialysis Risk

One of the fundamental goals of the hemodialysis prescription is to maintain serum potassium levels within a narrow normal range during both the intradialytic and interdialytic intervals. Considering the extraordinarily high rate of cardiovascular mortality in the hemodialysis population, clinicians are obligated to explore whether factors related to dialytic potassium removal can be modified to improve clinical outcomes. Observational studies and circumstantial evidence suggest that extreme concentrations of serum and dialysate potassium can trigger cardiac arrest. In this review, we provide an overview of factors affecting overall potassium balance and factors modulating potassium dialysate fluxes in dialysis, and we review data linking serum and dialysate potassium concentrations with arrhythmias, cardiovascular events, and mortality. We explore potential interactions between serum and dialysate magnesium levels and risks associated with dialysate potassium levels. Finally, we conclude with proposed dialytic and novel nondialytic approaches to optimize outcomes related to potassium homeostasis in patients on hemodialysis. Dialysis clinicians need to consider changes in the overall clinical scenario when choosing dialysate potassium concentrations, and an effective change in practice will require more frequent serum potassium monitoring and responsive dialysis care teams.

Reduced Mortality in Maintenance Haemodialysis Patients on High versus Low Dialysate Magnesium: A Pilot Study

Background: Although low magnesium levels have been associated with an increased mortality in dialysis patients, they are kept low by routinely-used dialysates containing 0.50 mmol/L magnesium. Thus, we investigated the impact of a higher dialysate magnesium concentration on mortality. Methods: 25 patients on high dialysate magnesium (HDM) of 0.75 mmol/L were 1:2 matched to 50 patients on low dialysate magnesium (LDM) of 0.50 mmol/L and followed up for 3 years with regards to all-cause and cardiovascular mortality. Patients were matched according to age, gender, a modified version of the Charlson Comorbidity Index (CCI), and smoking status. Results: During the follow-up period, five patients died in the HDM and 18 patients in the LDM group. Patients in the HDM group had significantly higher ionized serum magnesium levels than matched controls (0.64 ± 0.12 mmol/L vs. 0.57 ± 0.10 mmol/L, p = 0.034). Log rank test showed no difference between treatment groups for all-cause mortality. After adjustment for age and CCI, Cox proportional hazards regression showed that HDM independently predicted a 65% risk reduction for all-cause mortality (hazard ratio 0.35, 95% confidence interval [CI]: 0.13, 0.97). Estimated 3-year probability of death from a cardiovascular event was 14.5% (95% CI: 7.9, 25.8) in the LDM group vs. 0% in the HDM group. Log rank test found a significant group difference for cardiovascular mortality (χ² = 4.15, p = 0.042). Conclusions: Our data suggests that there might be a beneficial effect of an increased dialysate magnesium on cardiovascular mortality in chronic dialysis patients.

Hypomagnesemia and cause-specific mortality in hemodialysis patients: 5-year follow-up analysis

INTRODUCTION

The aim of this prospective study was to evaluate the association between serum magnesium (Mg) and mortality, in particular the cause-specific mortality of Mg and other risk factors in hemodialysis (HD) patients.

METHODS

We studied a cohort of 185 HD patients receiving thrice-weekly HD treatment, on a dialysate Mg concentration of 0.5 mmol/L. We stratified 3 patient groups according to the level of Mg: lower (<1.1 mmol/L), intermediate-reference (1.1 to <1.3 mmol/L), and higher (Mg >1.3 mm/L).

RESULTS

During the 5-year follow-up, 60 patients died, with cardiovascular (CV) disease as the predominant cause (73.3%). Hazard ratio (HR) for all-cause and CV mortality were 2.55 and 2.67 in the lower versus intermediate Mg group, but there was no significant association between the higher and intermediate Mg group. Univariate Cox regression analysis showed that Mg <1.1 versus 1.1-1.30 mml/L with HR 2.34, was a significant univariate predictor for increased mortality in addition to the Hb <110 g/L, Alb <40 g/L, C-reactive protein (CRP) ≥10 mg/L and brain natriuretic peptide >1,200 pg/mL. However, in the multivariate analysis only CRP ≥10 mg/L with HR 3.89 was a significant predictor of mortality. Subgroup analyses showed that among patients with CRP >10 mg/L, HR for all-cause and CV mortality of the lower versus intermediate Mg group were 1.96 and 2.39, respectively, not reaching significance for the higher versus intermediate Mg group. Conversely, there was no association between Mg level and all-cause and CV mortality within these 3 groups among patients with CRP <10 mg/L.

CONCLUSIONS

Lower serum Mg level was significantly associated with an increased all-cause and cardiovascular mortality in HD patients, especially in inflamed patients.

Magnesium Counteracts Vascular Calcification: Passive Interference or Active Modulation?

Over the last decade, an increasing number of studies report a close relationship between serum magnesium concentration and cardiovascular disease risk in the general population. In end-stage renal disease, an association was found between serum magnesium and survival. Hypomagnesemia was identified as a strong predictor for cardiovascular disease in these patients. A substantial body of in vitro and in vivo studies has identified a protective role for magnesium in vascular calcification. However, the precise mechanisms and its contribution to cardiovascular protection remain unclear. There are currently 2 leading hypotheses: first, magnesium may bind phosphate and delay calcium phosphate crystal growth in the circulation, thereby passively interfering with calcium phosphate deposition in the vessel wall. Second, magnesium may regulate vascular smooth muscle cell transdifferentiation toward an osteogenic phenotype by active cellular modulation of factors associated with calcification. Here, the data supporting these major hypotheses are reviewed. The literature supports both a passive inorganic phosphate-buffering role reducing hydroxyapatite formation and an active cell-mediated role, directly targeting vascular smooth muscle transdifferentiation. However, current evidence relies on basic experimental designs that are often insufficient to delineate the underlying mechanisms. The field requires more advanced experimental design, including determination of intracellular magnesium concentrations and the identification of the molecular players that regulate magnesium concentrations in vascular smooth muscle cells.

The effect of magnesium supplementation on vascular calcification in chronic kidney disease-a randomised clinical trial (MAGiCAL-CKD): essential study design and rationale

INTRODUCTION

Chronic kidney disease (CKD) is associated with an increased risk of cardiovascular disease and mortality, which is thought to be caused by increased propensity towards vascular calcification (VC). Magnesium (Mg) inhibits phosphate-induced VC in vitro and in animal models and serum Mg is inversely associated with cardiovascular mortality in predialysis CKD and in end-stage renal disease. This paper will describe the design and rationale of a randomised double-blinded placebo-controlled multicentre clinical trial, which will investigate whether oral Mg supplementation can prevent the progression of coronary artery calcification (CAC) in subjects with predialysis CKD.

METHODS AND ANALYSIS

We will randomise 250 subjects with estimated glomerular filtration rate of 15 to 45 mL/min/1.73 m² to 12 months treatment with either slow-release Mg hydroxide 30 mmol/day or matching placebo in a 1:1 ratio. The primary end point is change in CAC score as measured by CT at baseline and after 12 months treatment. Secondary end points include change in pulse wave velocity, bone mineral density, measures of mineral metabolism and clinical end points related to cardiovascular and renal events.

ETHICS AND DISSEMINATION

This trial has been approved by the local biomedical research ethics committees and data protection agencies and will be performed in accordance with the latest revision of the Helsinki Declaration. The trial will examine for the first time the effect of increasing the uptake of a putative VC inhibitor (ie, Mg) on progression of CAC in subjects with predialysis CKD.

TRIAL REGISTRATION NUMBER

NCT02542319, pre-results.

Clinical aspects of magnesium physiology in patients on dialysis

Magnesium balance is infrequently discussed in the dialysis population, and the clinical consequences of derangements in magnesium homeostasis are incompletely understood. There is an association between hypomagnesemia and adverse outcomes including increases in cardiovascular disease and mortality, while elevated magnesium levels have also been linked with complications such as osteomalacia. In this review, we discuss the features of magnesium physiology relevant to dialysis patients and provide an updated summary of the literature linking magnesium derangements with bone disease, cardiovascular disease, sudden cardiac death, and mortality.

Lower serum magnesium is associated with vascular calcification in peritoneal dialysis patients: a cross sectional study

BACKGROUND

Coronary artery calcification (CAC) is highly prevalent among dialysis patients and is associated with increased cardiovascular and all cause mortality. Magnesium (Mg) inhibits vascular calcification in animal and in-vitro studies but whether the same effect occurs in humans is uncertain.

METHODS

A single centre cross-sectional study of 80 prevalent peritoneal dialysis (PD) patients; on PD only for a minimum of 3 months. A radiologist blinded to patient status calculated their abdominal aortic calcification (AAC) scores on lateral lumbar spine radiographs, a validated surrogate for CAC.

RESULTS

Eighty patients provided informed consent and underwent lumbar spine radiography. The mean serum Mg was 0.8 mmol/L (standard deviation 0.2) and mean AAC score 8.9 (minimum 0, maximum 24). A higher serum Mg level was associated with a lower AAC score (R ² = 0.06, unstandardized coefficient [B] = -7.81, p = 0.03), and remained after adjustment for age, serum phosphate, serum parathyroid hormone, low-density lipoprotein cholesterol, smoking history, and diabetes (model adjusted R ² = 0.36, serum Mg and AAC score B = -11.44, p = 0.00). This translates to a 0.1 mmol/L increase in serum Mg being independently associated with a 1.1-point decrease in AAC score.

CONCLUSIONS

Our findings suggest that Mg may inhibit vascular calcification. If this association is replicated across larger studies with serial Mg and vascular calcification measurements, interventions that increase serum Mg and their effect on vascular calcification warrant further investigation in the PD population.