Hypomagnesemia in type 2 diabetic nephropathy: a novel predictor of end-stage renal disease

Association of serum magnesium levels with renal prognosis in patients with chronic kidney disease

BACKGROUND

Magnesium deficiency is associated with various health conditions, but its impact on the progression of chronic kidney disease (CKD) remains unclear. This study aimed to investigate the association between serum magnesium levels and prognosis of renal function in CKD patients.

METHODS

This is an analysis of the Japan Chronic Kidney Disease Database Ex　(J-CKD-DB-Ex), which is a multicenter prospective cohort including CKD patients enrolled from January 1, 2014 to December 31, 2020. We included adult outpatients with CKD stage G3 and G4 at the time of initial magnesium measurement. Patients were classified by magnesium levels as low (<1.7 mg/dl), normal (1.7-2.6 mg/dl), or high (>2.6 mg/dl). The primary outcomes were the composite of an eGFR < 15 ml/min/1.73 m2 or a ≥30% reduction in eGFR from the initial measurement, which was defined as CKD progression. We applied the Kaplan-Meier analysis and Cox regression hazard model to examine the association between magnesium levels and CKD progression.

RESULTS

The analysis included 9868 outpatients during the follow-up period. The low magnesium group was significantly more likely to reach CKD progression. Cox regression, adjusting for covariates and using the normal magnesium group as the reference, showed that the hazard ratio for the low magnesium group was 1.20 (1.08-1.34). High magnesium was not significantly associated with poor renal outcomes compared with normal magnesium.

CONCLUSION

Based on large real-world data, this study demonstrated that low magnesium levels are associated with poorer renal outcomes.

Association of urinary calcium excretion with chronic kidney disease in patients with type 2 diabetes

PURPOSE

Herein, we investigated the correlation between urinary calcium excretion (UCaE) and chronic kidney disease (CKD) in patients with type 2 diabetes mellitus (T2DM).

METHODS

From August 2018 to January 2023, a total of 2031 T2DM patients providing 24-h urine samples were included in the final analyses. Patients were separated into four cohorts, based on the UCaE quartiles. We then analyzed renal functional indicators like estimated glomerular filtration rate (eGFR) and urinary albumin excretion (UAE) among the four groups. Lastly, we utilized multivariable logistic regression models to investigate the correlation between UCaE and CKD.

RESULTS

After adjusting for confounding factors, we observed a decreasing trend in CKD prevalence (36.3%, 13.0%, 7.5%, and 6.6%, respectively, P < 0.001) across the UCaE quartiles. Albuminuria (55.5% vs. 40.0%, 36.5%, 37.4%) and macroalbuminuria prevalence (20.0% vs. 9.3%, 5.2%, 5.7%) in the lowest quartile were markedly elevated, compared to the remaining three quartiles (P < 0.001). Meanwhile, the eGFR level (P < 0.001) showed a clearly increasing trend across the UCaE quartiles, and patients with moderate-to-severe decreases in eGFR levels (with cutoff limits at 30-59, 15-30, and < 15 mL/min/1.73m2) were mostly found in the lowest quartile (P < 0.001). Logistic regression analysis revealed that patients in the lowest quartile experienced an enhanced prevalence of CKD, relative to those in the highest quartile (odds ratio: 5.90, 95% confidence interval: 3.60-9.67, P < 0.001).

CONCLUSION

Decreased UCaE was independently associated with the CKD prevalence in T2DM patients.

Impact of magnesium supplementation on clinical outcome and disease progression of patients with diabetic nephropathy: a prospective randomized trial

Background

Magnesium (Mg) deficiency is closely linked with proteinuria.

Objectives

To assess the impact of oral Mg citrate supplementation on the clinical outcome of diabetic nephropathy (DN) patients.

Design

This was a prospective, randomized, controlled, open-label study.

Methods

Sixty DN patients were recruited from Nephrology and Endocrinology departments, Ain Shams University Hospitals, Cairo, Egypt. Patients were assigned by stratified randomization based on their Mg status, to either Mg citrate group, (n = 30), who received the standard regimen + oral Mg citrate 2.25 g/day or Control group, (n = 30), who received the standard regimen only. The primary endpoint was a change in urinary albumin to creatinine ratio (UACR) after 12 weeks. Secondary outcomes were insulin resistance, glycemic control, lipid profile, serum osteocalcin, quality of life (QoL) and Mg tolerability.

Results

Out of a total of 60 patients enrolled, only 54 patients (26 in Mg citrate group and 28 in the control group) completed the study. Groups were comparable at baseline. The UACR median percent reduction was significantly higher in the Mg citrate group (-6.87%) versus (-0.9%) in the Control group, p = 0.001. After 12 weeks, the estimated glomerular filtration rate significantly improved in the Mg citrate group versus Control group (p = 0.001). Comparable change was observed in glycemic indices. Lipid profile significantly improved in the Mg citrate group versus Control group (p = 0.001). Serum osteocalcin levels significantly declined in the Mg citrate group (p = 0.001) versus control group. Regarding QoL, the total score and all domains significantly improved in the Mg citrate group compared to control. The Mg supplement was tolerable with only mild reported side effects that required no intervention.

Conclusion

Oral Mg citrate supplementation improved microalbuminuria in DN patients. It also had favorable effects on serum osteocalcin, lipid profile and QoL with no reported major side effects.

Trial registration

ClinicalTrials.gov identifier: NCT03824379.

Global burden and influencing factors of chronic kidney disease due to type 2 diabetes in adults aged 20-59 years, 1990-2019

Population structure and lifestyles may have contributed to the epidemiological status of Chronic Kidney Disease due to Type 2 Diabetes (CKD-T2D). This study is a secondary data analysis. Using data from the Global Burden of Disease Study, we describe the changes in CKD-T2D burden and its influencing factors in the population aged 20-59 years from 1990 to 2019. Globally, the incidence, death, and Disability Adjusted Life Years (DALYs) rate of CKD-T2D showed an upward trend and increased with age, and the burden in males was higher than that in females. Population growth and aging were important driving factors for the increase of CKD-T2D DALY burden, while high systolic blood pressure and high body-mass index were the primary attributable risk factors. High body-mass index exhibited higher contributions to high Socioeconomic Development Index (SDI) countries, whereas low SDI countries were more impacted by high systolic blood pressure. The population attributable fraction of CKD-T2D DALY caused by high body-mass index was positively correlated with SDI, while high temperature and lead exposure were negatively correlated. Therefore, strengthening disease screening for people aged 20-59 years and formulating early intervention measures based on the level of socioeconomic development may effectively alleviate the burden of CKD-T2D.

Magnesium in Kidney Function and Disease-Implications for Aging and Sex-A Narrative Review

Magnesium (Mg) has a vital role in the human body, and the kidney is a key organ in the metabolism and excretion of this cation. The objective of this work is to compile the available evidence regarding the role that Mg plays in health and disease, with a special focus on the elderly population with chronic kidney disease (CKD) and the eventual sex differences. A narrative review was carried out by executing an exhaustive search in the PubMed, Scopus, and Cochrane databases. Ten studies were found in which the role of Mg and sex was evaluated in elderly patients with CKD in the last 10 years (2012-2022). The progression of CKD leads to alterations in mineral metabolism, which worsen as the disease progresses. Mg can be used as a coadjuvant in the treatment of CKD patients to improve glomerular filtration, but its use in clinical applications needs to be further characterized. In conclusion, there's a need for well-designed prospective clinical trials to advise and standardize Mg supplementation in daily clinical practice, taking age and sex into consideration.

Plant-Dominant Low Protein Diet: A Potential Alternative Dietary Practice for Patients with Chronic Kidney Disease

Dietary protein restriction has long been a cornerstone of nutritional therapy for patients with chronic kidney diseases (CKD). However, the recommended amount of dietary protein intake is different across guidelines. This is partly because previous randomized controlled trials have reported conflicting results regarding the efficacy of protein restriction in terms of kidney outcomes. Interestingly, a vegetarian, very low protein diet has been shown to reduce the risk of kidney failure among patients with advanced CKD, without increasing the incidence of hyperkalemia. This finding suggests that the source of protein may also influence the kidney outcomes. Furthermore, a plant-dominant low-protein diet (PLADO) has recently been proposed as an alternative dietary therapy for patients with CKD. There are several potential mechanisms by which plant-based diets would benefit patients with CKD. For example, plant-based diets may reduce the production of gut-derived uremic toxins by increasing the intake of fiber, and are useful for correcting metabolic acidosis and hyperphosphatemia. Plant proteins are less likely to induce glomerular hyperfiltration than animal proteins. Furthermore, plant-based diets increase magnesium intake, which may prevent vascular calcification. More evidence is needed to establish the efficacy, safety, and feasibility of PLADO as a new adjunct therapy in real-world patients with CKD.

Preoperative Ionized Magnesium Levels and Risk of Acute Kidney Injury After Cardiac Surgery

RATIONALE & OBJECTIVE

Although postoperative acute kidney injury (AKI) is a serious complication after cardiac surgery, preventive measures are limited. Despite the known association of preoperative low magnesium levels with cardiac surgery-related atrial fibrillation, the association between preoperative magnesium concentration and postoperative AKI has not been fully elucidated. This study evaluated the association between preoperative serum magnesium level and the development of AKI after cardiac surgery.

STUDY DESIGN

Retrospective observational cohort study.

SETTING & PARTICIPANTS

Patients aged≥18 years who underwent cardiac surgery at 2 South Korean tertiary hospitals between 2006 and 2020 were identified from medical records. Patients with missing information, an estimated glomerular filtration rate<15mL/min/1.73m², receiving maintenance dialysis, or a history of AKI treated by dialysis within 1 year before surgery were excluded.

EXPOSURE

Preoperative serum magnesium levels.

OUTCOME

Postoperative AKI within 48 hours after surgery, defined using the Acute Kidney Injury Network (AKIN) criteria, and dialysis-treated AKI within 30 days after surgery.

ANALYTICAL APPROACH

Multivariable logistic regression analysis.

RESULTS

Among the 9,766 patients (median age, 64.0 years; 60.1% male), postoperative AKI and dialysis-treated AKI were observed in 40.1% and 4.3% patients, respectively. Postoperative AKI was more prevalent in patients with lower serum magnesium levels (44.9%, 41.4%, 39.4%, and 34.8% in quartiles 1-4, respectively). Multivariable logistic regression analysis revealed that the odds ratios (ORs) for postoperative AKI were progressively larger across progressively lower quartiles of serum magnesium concentration (adjusted ORs of 1.53 [95% CI, 1.33-1.76], 1.29 [95% CI, 1.12-1.48], 1.15 [95% CI, 1.01-1.31] for quartiles 1-3, respectively, relative to quartile 4, P for trend<0.001). Preoperative hypomagnesemia (serum magnesium level<1.09mg/dL) was also significantly associated with AKI (adjusted OR, 1.39 [95% CI, 1.10-1.77]) and dialysis-treated AKI (adjusted OR, 1.67 [95% CI, 1.02-2.72]).

LIMITATIONS

Causality could not be evaluated in this observational study.

CONCLUSIONS

Lower serum magnesium levels were associated with a higher incidence of AKI in patients undergoing cardiac surgery.

Incidence, Pathogenesis, and Management of Proton Pump Inhibitor-Induced Nephrotoxicity

Proton pump inhibitors are widely used in the treatment of various acid-related diseases and are among the most commonly used drugs. Studies estimate that 25-70% of proton pump inhibitors are prescribed for inappropriate treatments, doses, and indications, where the benefits of proton pump inhibitor use may be less than the risk of adverse drug reactions for many patients. Acute interstitial nephritis is an immune-mediated atypical kidney injury in the long-term use of proton pump inhibitors that causes problems for clinicians and patients. In this review, we summarize the current knowledge of proton pump inhibitors inducing acute interstitial nephritis, chronic kidney disease, and even end-stage renal disease in terms of incidence, pathogenesis, factors, clinical features, and diagnosis. We discuss how these factors change under conditions of acute interstitial nephritis, chronic kidney disease, and end-stage renal disease. The purpose of this review is to assess the current evidence to help clinicians and patients interpret the potential causal relationship between proton pump inhibitor intake and nephrotoxicity. This prompts clinicians to consider the appropriate dose and duration of proton pump inhibitor therapy to avoid inappropriate use.

The association of serum magnesium and chronic kidney disease: a two-sample mendelian randomization study of European descent

BACKGROUND

Previous observational studies focused on the association of serum magnesium (SMg) and chronic kidney disease (CKD), but the conclusion was inconsistent. To investigate the causal relationship of SMg and CKD, we performed a two-sample mendelian randomization (TSMR) analysis using publicly datasets.

METHOD

In mendelian randomization (MR) analysis, we used single nucleotide polymorphisms (SNPs) which had genetic statistical significance with SMg but not associated with kidney function and confounding factors as instrumental variable (IV). To select SNPs, we used publicly database of Genome Wide Association Study (GWAS) and Chronic Kidney Disease Genetics (CKDGen) Confirms. We used inverse-variance weighted (IVW), weighted median, MR-Egger regression, weighted mode, and simple mode approaches in TSMR analysis.

RESULTS

We selected 4 SNPs (rs4072037, rs7965584, rs11144134 and rs448378) as IV. In IVW approach, the result of MR analysis for CKD was OR = 0.55, 95% CI: 0.06, 4.75, P = 0.58; for estimated glomerular filtration rate from creatinine (eGFR)crea was β = -0.06, 95% CI: -1.08, 0.07, P = 0.39; for estimated glomerular filtration rate from cystatin C (eGFR)cys was β = -0.03, 95% CI: -0.43, 0.36, P = 0.86, respectively per SD increase in SMg. When subgroup by diabetes mellitus (DM), the results for DM-eGFRcrea was β = -0.33, 95% CI: -0.85, 0.19, P = 0.21; and for non-DM-eGFRcrea was β = -0.03, 95% CI: -0.16, 0.11, P = 0.71. The results of other four MR approaches were consistent with IVW approach (all P > 0.05).

CONCLUSION

Our TSMR analysis showed that SMg had no causal effect on kidney function and progress CKD in European descent. As for the results about overall population, the verified study is needed in future study.

The emerging role of magnesium in CKD

Increasing evidence has suggested a clinical relevance of magnesium in the context of vascular calcification and mortality among patients with CKD. Hypomagnesemia is not rare among non-dialysis CKD patients despite their decreased glomerular filtration rates; the prevalence rate was about 15% even in CKD stages G4 and G5. Among several potential causes of hypomagnesemia, tubular dysfunction/interstitial fibrosis may play a pivotal role in the development of hypomagnesemia in CKD, which impairs tubular magnesium reabsorption. Magnesium deficiency may, in turn, be involved in the progression of CKD. An in vitro study has revealed that magnesium deficiency aggravates tubular cell death and inflammation induced by phosphate load. In a cohort study of patients with CKD, low-serum magnesium levels enhanced the risk of end-stage kidney disease related to high-serum phosphate levels, suggesting a close relationship between magnesium deficiency and phosphate toxicity. More importantly, magnesium has a potent capacity to inhibit the calcification of vascular smooth muscle cells induced by phosphate. A randomized trial has shown the efficacy of oral magnesium oxide in retarding the progression of coronary artery calcification among non-dialysis CKD patients. Thus, magnesium might provide better cardiovascular prognosis; indeed, hemodialysis patients with mild hypermagnesemia exhibited the lowest mortality rate. Further randomized trials are needed to assess the impact of magnesium in terms of hard clinical outcomes among CKD patients.

Serum Magnesium, Blood Pressure, and Risk of Hypertension and Chronic Kidney Disease Progression in the CRIC Study

[Figure: see text].

Proton Pump Inhibitor and Tacrolimus Uses are Associated With Hypomagnesemia in Connective Tissue Disease: a Potential Link With Renal Dysfunction and Recurrent Infection

Background: Low levels of serum magnesium perturb renal tubular cell function and lymphocytes, resulting in renal deterioration and an imbalance in mononuclear cells. This study investigated the mechanism and influence of hypomagnesemia in patients with connective tissue disease.

Methods: We retrospectively evaluated patients with connective tissue disease and available serum magnesium data who visited Keio University Hospital in 2019. Patients were divided into two groups: those with (serum magnesium < 1.8 mg/dl) and those without hypomagnesemia; their rates of hospitalization for severe infection and cumulative renal deterioration were compared. Patients’ fractions of lymphocytes and natural killer and dendritic cell subsets, as measured by fluorescence-activated cell sorting (FACS) analysis, were also compared.

Results: Among 284 patients, hypomagnesemia was detected in 63 (22.2%). Multivariate analysis revealed that the use of proton pump inhibitors [odds ratio (OR), 1.48; p = 0.01] and tacrolimus (OR, 6.14; p < 0.01) was independently associated with hypomagnesemia. In addition, the renal deterioration rate was significantly higher in tacrolimus and/or proton pump inhibitor users with hypomagnesemia (p = 0.01). The hospitalization rate for severe infection was also higher in patients with hypomagnesemia (p = 0.04). FACS analysis showed lower CD8+ T cell, CD19+ B cell, natural killer cell, and dendritic cell counts in patients with hypomagnesemia (p = 0.03, p = 0.02, p = 0.02, and p = 0.03, respectively).

Conclusion: The use of tacrolimus and proton pump inhibitors may be associated with hypomagnesemia and lead to poor renal outcomes and severe infection in patients with connective tissue disease.

Retrospective study of factors associated with progression and remission/regression of diabetic kidney disease-hypomagnesemia was associated with progression and elevated serum alanine aminotransferase levels were associated with remission or regression

Aim

This study was aimed at retrospectively investigating some common clinical factors, including the serum level of magnesium (Mg), associated with progression and remission/regression of diabetic kidney disease (DKD).

Methods

The subjects were 690 Japanese patients with type 2 diabetes mellitus who were receiving treatment with oral antidiabetic drugs other than SGLT2 inhibitors. Routine clinical data were collected on the first and last day of the observation period. The prognosis of DKD is categorized into four stages according to the Kidney Disease Improving Global Outcomes classification. Progression was defined as transition from any of the lower three risk categories (LR, MIR, HR) at the start of the observation period, to the VHR stage/category at the end of the observation period. Remission/regression was defined as improvement of the risk category by at least one stage from the start to the end of the observation period. Factors associated with progression and regression/remission were investigated using Cox proportional hazards analysis. Furthermore, the factors associated with the annual decrease in eGFR of 5 ml/min/1.73 m² or more were examined by logistic regression analysis. Factors associated with transition of urinary protein negative to trace or positive, or transition of negative or trace to positive, were investigated by Cox proportional hazard analysis.

Results

The observation period was 2251 ± 1614 days. Age (Exp [B] = 1.10, 95% CI; 1.06-1.14; P < 0.01; 1 year old), serum Mg (Exp [B] = 0.82, 95% CI; 0.71-0.95; P < 0.01); 0.1 mg/dl), and serum HbA1c (Exp [B] = 1.03, 95% CI; 1.01-1.05; P < 0.01: 0.1%) were associated with progression of DKD; on the other hand, serum ALT was associated with the likelihood of remission/regression of DKD (Exp [B] = 1.01, 95% CI; 1.002-1.018; P < 0.05; 1 IU/L). The decline in eGFR was associated with higher HbA1c levels, hypomagnesemia, and lower ALT. The new appearance of trace or overt proteinuria was correlated with higher HbA1c levels, advancing age, hypomagnesemia and hypertriglycemia.

Conclusion

Our findings confirmed previous reports that advancing age and serum HbA1c levels were associated with an increased risk of progression of DKD. Lower serum Mg concentrations were also found to be associated with a high risk of progression of DKD, and interventional studies are needed to confirm a causal relationship. Elevated HbA1c levels and hypomagnesemia were common factors in the decline in eGFR and the appearance of trace or overt proteinuria. Lower serum ALT levels were associated with the decline in eGFR. Since serum ALT is known to decrease as the renal function deteriorates, serum ALT is considered to be a marker of renal function.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-020-00483-1.

Serum magnesium in diabetic retinopathy: the association needs investigation

BACKGROUND

Magnesium has an essential role in glucose metabolism, and hypomagnesaemia is common in diabetes mellitus. However, the relationship between serum magnesium and diabetic retinopathy is poorly understood.

AIM

To determine the association between serum magnesium levels and retinopathy in type 2 diabetic patients with normal renal function and to correlate it with severity of retinopathy.

METHODS

This cross-sectional observational study was conducted in a semi-urban tertiary-care teaching hospital. Clinicodemographic profile and serum magnesium levels were determined in patients with type 2 diabetes mellitus (DM) with (group 1) and without (group 2) retinopathy. Serum magnesium levels were correlated with the presence and severity of retinopathy.

RESULTS

Of 104 type 2 DM patients, 50 had retinopathy. Younger age, longer duration of disease and poorer glycaemic control (p < 0.05) were found to be associated with retinopathy. The mean serum magnesium levels in patients with retinopathy and those without retinopathy were 1.63 ± 0.30 mg/dL and 1.76 ± 0.22 mg/dL, respectively (p = 0.029). Reduced serum magnesium was associated with elevated fasting sugars (p = 0.019) and female gender (p = 0.037). On comparative analysis of patients with sight-threatening diabetic retinopathy (STDR), non-STDR and no retinopathy by ANOVA test, patients with STDR had significantly lower serum magnesium (1.55 ± 0.33 mg/dL) (p = 0.031).

CONCLUSION

Serum magnesium levels were lower in patients with diabetic retinopathy. Patients with STDR had lower serum magnesium compared with those without STDR.

SUMMARY

Serum magnesium, studied extensively for its role in glucose metabolism, was found to be lower in patients with diabetic retinopathy compared with those without retinopathy. Sight-threatening diabetic retinopathy had significantly lower levels of serum magnesium.

Magnesium: The recent research and developments

Magnesium is the fourth most abundant mineral in the human body, which facilitates more than 300 enzymatic reactions. Magnesium is essential for nucleic material and protein synthesis, neuromuscular conduction, cardiac contractility, energy metabolism, and immune system function. Gastrointestinal system and kidneys closely regulate magnesium absorption and elimination to maintain adequate storage of magnesium. Magnesium deficiency has been linked to many diseases and poor health outcomes. Magnesium has also been proven to be an effective therapeutic agent in many diseases, such as bronchial asthma, cardiac arrhythmia, and pre-eclampsia.

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.

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.

Hypomagnesemia in the Cancer Patient

Hypomagnesemia is a common medical problem that contributes to the morbidity and mortality of patients with cancer. This review summarizes magnesium physiology and highlights the mechanisms underlying magnesium disturbances due to cancer and cancer treatment. The causes of hypomagnesemia can be categorized according to the pathophysiologic mechanism: decreased intake, transcellular shift, gastrointestinal losses, and kidney losses. Patients with cancer are at risk for opportunistic infections, frequently experience cardiovascular complications, and often receive classes of medications that cause or exacerbate hypomagnesemia. Also, cancer-specific therapies are responsible for hypomagnesemia, including platinum-based chemotherapy, anti-EGF receptor mAbs, human EGF receptor-2 target inhibitors (HER2), and calcineurin inhibitors. Urinary indices, such as the fractional excretion of magnesium, can provide useful information about the etiology. The management of hypomagnesemia depends on the magnitude of hypomagnesemia and the underlying cause. We recommended checking serum magnesium at the beginning of treatment and as part of routine monitoring throughout cancer treatment. Opportunities exist for potential research and practice improvement, including further characterization of hypomagnesemia regarding the clinical effect on cancer outcomes, preventing hypomagnesemia in patients receiving high-risk anticancer agents, and developing effective therapeutic strategies.

Circulating magnesium status is associated with type 2 diabetes remission after Roux-en-Y gastric bypass surgery: a long-term cohort study

BACKGROUND

Low serum magnesium levels predict cardiovascular and all-cause mortality in patients with typ 2 diabetes.

SETTING

Outpatient clinic of obesity and central hospital.

OBJECTIVES

To assess long-term alterations in circulating magnesium status after Roux-en-Y gastric bypass (RYGB) surgery and associations with remission of type 2 diabetes (T2D).

METHODS

Retrospective analysis of 5-year outcomes of plasma magnesium (p-Mg) and glucometabolic statuses in patients who underwent primary RYGB and who completed the annual follow-up program. Data were investigated from 84 patients without diabetes and 62 with T2D before RYGB, who showed either prolonged remission (n = 30), temporary remission (n = 16), or no remission (n = 16) after surgery.

RESULTS

Body mass indexes before RYGB were similar in patients with and without T2D, irrespective of remission. The patients not achieving remission showed longer diabetes durations; higher circulating glucose levels; more intensive antidiabetic drug treatment, including insulin; and significantly lower p-Mg concentrations (.73 [±.08] mmol/L compared with .80-.82 [±.07] mmol/L, respectively; P < .01) than the groups showing remission or without diabetes before surgery. After RYGB, the p-Mg increased similarly, by 10-12% in the groups with T2D before surgery, irrespective of remission; however, the nonremission group did not reach the p-Mg levels registered in the other groups after follow-up. The nonremission group reached .82 (.09) mmol/L, compared with .87 (.06) and .88 (.08) mmol/L (P < .05), respectively, in patients with remission or without a history of diabetes.

CONCLUSION

The p-Mg concentrations increased after RYGB, with similar increments irrespective of T2D remission; however, the nonremission group started from an inferior level and did not reach the p-Mg concentrations seen in the groups achieving remission or without a history of diabetes before surgery.

Posttransplantation Hypomagnesemia as a Predictor of Better Graft Function after Transplantation

BACKGROUND

Hypomagnesemia is frequently seen after transplantation and is particularly associated with the use of calcineurin inhibitors (CNIs).

METHODS

We conducted a retrospective, single-center analysis (2000-2013, N = 726) to explore the relationship between hypomagnesemia and long-term allograft outcome in kidney transplant recipients. For this study, a median serum magnesium (Mg) level of all measured Mg levels from 1 month to 1 year after renal transplantation was calculated.

RESULTS

For every increase in Mg by 0.1 mg/dL, the GFR decreased by 1.1 mL/min at 3 years posttransplant (p < 0.01) and by 1.5 mL/min at 5 years posttransplant. A median blood Mg level of ≥1.7 was found to be an independent predictor of a GFR <60 mL/min at 3 years posttransplant. The odds of having a GFR <60 mL/min 3 years posttransplant was almost 2-fold higher in the high Mg group than in the low Mg group.

CONCLUSIONS

Hypomagnesemia from 1 to 12 months after renal transplantation is associated with a better allograft function up to 5 years posttransplant. This relationship was found to hold true after accounting for baseline allograft function and the presence of slow graft function.

Serum magnesium, bone-mineral metabolism markers and their interactions with kidney function on subsequent risk of peripheral artery disease: the Atherosclerosis Risk in Communities Study

BACKGROUND

Few studies have investigated the association of magnesium levels with incident peripheral artery disease (PAD) despite emerging evidence of magnesium contributing to vascular calcification. Moreover, no data are available on whether the magnesium-PAD relationship is independent of or modified by kidney function.

METHODS

A cohort of 11 839 participants free of PAD in the Atherosclerosis Risk in Communities Study at Visit 2 (1990-92) was studied. We investigated the association of serum magnesium and other bone-mineral metabolism markers [calcium, phosphorus, intact parathyroid hormone (iPTH) and intact fibroblast growth factor-23] with incident PAD using multivariable Cox proportional hazards regression.

RESULTS

Over a median of 23 years, there were 471 cases of incident PAD. The hazard ratio for incident PAD in Quartile 1 (<1.5 mEq/L) versus Quartile 4 (>1.7 mEq/L) of magnesium was 1.96 (95% confidence interval 1.40-2.74) after adjustment for potential confounders. Lower magnesium levels were associated with greater incidence of PAD, particularly in those with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 (n = 11 606). In contrast, the association was largely flat in those with eGFR <60 mL/min/1.73 m2 (n = 233) with P-for-interaction 0.03. Among bone-mineral metabolism markers, only higher iPTH showed an interaction with kidney function (P-for-interaction 0.01) and iPTH >65 pg/mL was significantly related to PAD only in those with eGFR <60 mL/min/1.73 m2.

CONCLUSIONS

Lower magnesium was independently associated with incident PAD, but this association was significantly weaker in those with reduced kidney function. In contrast, higher iPTH levels were particularly related to PAD risk in this clinical population.

Hypomagnesemia and survival in patients with head and neck cancers who received primary concurrent chemoradiation

BACKGROUND

Prior research has confirmed that persistent hypomagnesemia was predictive of shorter survival among patients with ovarian cancer who received carboplatin-based chemotherapy. In the current retrospective study, the authors examined the association between hypomagnesemia and survival in patients with head and neck cancer who received concurrent chemoradiation with weekly infusions of cisplatin and/or carboplatin.

METHODS

Patients with head and neck cancers who had undergone chemoradiation with cisplatin and/or carboplatin between January 1, 2010, and December 31, 2014, were included. Patients were aged ≥18 years with pathology of squamous cell carcinoma of the larynx, oral cavity, or oropharynx who had received at least 30 fractions of radiotherapy with concurrent weekly cisplatin and/or carboplatin. Pathology features, laboratory results, Eastern Cooperative Oncology Group performance status, social histories, and survival were recorded. The association between hypomagnesemia and survival was analyzed controlling for known prognostic factors.

RESULTS

The final cohort consisted of 439 patients with a median age of 59 years. A greater frequency of hypomagnesemia during the treatment course was found to be significantly associated with shorter survival (hazard ratio [HR], 1.13; P = .033) independent of age (HR, 1.65; P = .042), cancer site (nonoropharynx vs oropharynx: HR, 2.15 [P = .003]), Eastern Cooperative Oncology Group performance status (>1 vs ≤1: HR, 2.64 [P < .001]), and smoking history (smoker vs nonsmoker: HR, 1.88 [P = .012]). In addition, more severe hypomagnesemia was associated with shorter survival compared with the milder form.

CONCLUSIONS

The frequency and severity of hypomagnesemia during treatment are prognostic of survival for patients with head and neck cancers who are receiving concurrent chemoradiation with cisplatin and/or carboplatin. A prospective study is needed to investigate the impact of the prevention of hypomagnesemia on survival in this patient population.

Effects and association of pro-oxidants with magnesium in patients with diabetic nephropathy

Diabetic nephropathy (DN) is the most common microvascular complication observed in patients with type-2 diabetes mellitus. Furthermore, magnesium (Mg) deficiency is a common problem in diabetic patients. In this study, we estimated the levels of Mg, which is an important trace element and pro-oxidant marker, and then evaluated the association between serum Mg and pro-oxidants in patients with DN. In the present study, 200 patients were enrolled and were divided into two groups. The control and DN groups consisted of 100 healthy individuals and 100 patients with DN, respectively. Serum Mg, total anti-oxidant capacity (TAC), and superoxide dismutase (SOD) levels were estimated using the Calmagite, Koracevic, and Marklund and Marklund methods, respectively. Glutathione (GSH) and malondialdehyde (MDA) levels were estimated using the Tietze F and Jean CD method, respectively. Mg levels were found to be significantly decreased in the DN group in comparison to the control group. Anti-oxidant markers were statistically significantly reduced (P <0.001), whereas MDA levels were statistically significantly elevated (P <0.001) in the DN group compared to the control group. There was a significant positive association of Mg with TAC, SOD, and GSH. A statistically significant negative association of Mg with MDA (r = -0.302, P <0.001, n = 100) was also observed. An apparent relationship was observed between hypomagnesemia and oxidative stress in patients with DN. Lower levels of Mg and oxidative stress were also strongly linked.

Medication burden and inappropriate prescription risk among elderly with advanced chronic kidney disease

BACKGROUND

Elderly patients with chronic kidney disease (CKD) frequently present comorbidities that put them at risk of polypharmacy and medication-related problems. This study aims to describe the overall medication profile of patients aged ≥75 years with advanced CKD from a multicenter French study and specifically the renally (RIMs) and potentially inappropriate-for-the-elderly medications (PIMs) that they take.

METHODS

This is a cross-sectional analysis of medication profiles of individuals aged ≥75 years with eGFR < 20 ml/min/1.73 m2 followed by a nephrologist, who collected their active prescriptions at the study inclusion visit. Medication profiles were first analyzed according to route of administration, therapeutic classification. Second, patients were classified according to their risk of potential medication-related problems, based on whether the prescription was a RIM or a PIM. RIMs and PIMs have been defined according to renal appropriateness guidelines and to Beer's criteria in the elderly. RIMs were subclassified by 4 types of category: (a) contraindication; (b) dose modification is recommended based on creatinine clearance (CrCl); (c) dose modification based on CrCl is not recommended but a maximum daily dose is mentioned, (d) no specific recommendations based on CrCl: "use with caution", "avoid in severe impairment", "careful monitoring of dose is required" "reduce the dose".

RESULTS

We collected 5196 individual medication prescriptions for 556 patients, for a median of 9 daily medications [7-11]. Antihypertensive agents, antithrombotics, and antianemics were the classes most frequently prescribed. Moreover, 77.0% of patients had at least 1 medication classified as a RIM. They accounted 31.3% of the drugs prescribed and 9.25% was contraindicated drugs. At least 1 PIM was taken by 57.6 and 45.5% of patients had at least one medication classified as RIM and PIM. The prescriptions most frequently requiring reassessment due to potential adverse effects were for proton pump inhibitors and allopurinol. The PIMs for which deprescription is especially important in this population are rilmenidine, long-term benzodiazepines, and anticholinergic drugs such as hydroxyzine.

CONCLUSION

We showed potential drug-related problems in elderly patients with advanced CKD. Healthcare providers must reassess each medication prescribed for this population, particularly the specific medications identified here.

TRIAL REGISTRATION

NCT02910908.

Cluster and Factor Analysis of Elements in Serum and Urine of Diabetic Patients with Peripheral Neuropathy and Healthy People

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes mellitus, presented as a major teratogenic cause worldwide. This study discussed alternation and correlation of magnesium (Mg), calcium (Ca), copper (Cu), zinc (Zn), iron (Fe), chromium (Cr), and selenium (Se) among DPN patients and healthy people using multivariate statistical analysis. Fifty patients with DPN were recruited from endocrinology department, First Hospital of Jilin University between January 2010 and October 2011 and also 50 healthy subjects were enrolled at the same time. Inductively coupled plasma mass spectrometry (ICP-MS) was used to assay elements in serum and urine. Cluster analysis was used to clarify alternation of elements' homogeneity. Factor analysis was performed to evaluate the most informative kinds of elements. Mg, Ca, Zn, and Cr in DPN patients were significantly lower in serum whereas significantly higher in urine. Elements were clustered into 4 or 5 clusters based on internal association using between-groups linkage algorithm. Serum Cr, Se, and Fe were grouped, and Mg related to Ca more closely in both serum and urine in DPN. Factor analysis revealed discrepancies of elements' contribution. Cr, Se, and Fe appeared to be the most crucial factors contributing to DPN. Mg, Ca, Zn, and Cu were more influential, whereas Cr became less potent to disease. Contributed value of elements could be determined and specified using loadings in scree plot. Future studies and delicate statistical models should be applied.

Metformin regulates TRPM6, a potential explanation for magnesium imbalance in type 2 diabetes patients

Metformin therapy is associated with lower serum magnesium (Mg²⁺) levels in type 2 diabetes patients. The TRPM6 channel determines the fine-tuning of Mg²⁺ (re)absorption in intestine and kidney. Therefore, we aimed to investigate the short- and long-term effects of metformin on TRPM6. Patch clamp recordings and biotinylation assays were performed upon 1 h of incubation with metformin in TRPM6-transfected HEK293 cells. Additionally, 24 h of treatment of mDCT15 kidney and hCaco-2 colon cells with metformin was applied to measure the effects on endogenous TRPM6 expression by quantitative real-time PCR. To assess Mg²⁺ absorption, ²⁵Mg²⁺ uptake measurements were performed using inductively coupled plasma mass spectrometry. Short-term effects of metformin significantly increased TRPM6 activity and its cell surface trafficking. In contrast, long-term effects significantly decreased TRPM6 mRNA expression and ²⁵Mg²⁺ uptake. Metformin lowered TRPM6 mRNA levels independently of insulin- and AMPK-mediated pathways. Moreover, in type 2 diabetes patients, metformin therapy was associated with lower plasma Mg²⁺ concentrations and fractional excretion of Mg²⁺. Thereby, short-term metformin treatment increases TRPM6 activity explained by enhanced cell surface expression. Conversely, long-term metformin treatment results in downregulation of TRPM6 gene expression in intestine and kidney cells. This long-term effect translated in an inverse correlation between metformin and plasma Mg²⁺ concentration in type 2 diabetes patients.

Oral Magnesium Supplementation Improved Lipid Profile but Increased Insulin Resistance in Patients with Diabetic Nephropathy: a Double-Blind Randomized Controlled Clinical Trial

Low serum magnesium concentrations were associated with development of renal failure. We aimed to determine whether magnesium supplementation improves renal function, insulin resistance, and metabolic profiles in patients with diabetic nephropathy. A total of 80 hypomagnesemic patients diagnosed with type 2 diabetes and early-stage nephropathy were recruited. Subjects received either daily magnesium oxide or placebo for 12 weeks. Biochemical and anthropometric variables were measured. Physical activity and dietary intakes were also recorded. This study was approved by the ethics committee of Isfahan University of Medical Sciences and was registered on the Iranian Registry of Clinical Trials website (IRCT registration no. IRCT201404271485N12). Serum magnesium levels were not changed significantly. Although the supplementation did not influence glycemic indices, patients in the magnesium group had greater insulin resistance compared with the placebo group after intervention (0.3 ± 2.3 μIU/mL vs. - 0.04 ± 2.05, P = 0.04). No significant changes were observed in serum total cholesterol, triglycerides, HDL, LDL, and total cholesterol/HDL cholesterol ratio. Furthermore, magnesium did not affect inflammation, serum levels of creatinine, and blood urine nitrogen. However, a marginal decrease in microalbuminuria (- 3.1 ± 2.2 mg/L vs. - 14 ± 9.9, P = 0.09) was observed. Oral magnesium supplementation slightly improved microalbuminuria but resulted in increased insulin resistance in patients with diabetic nephropathy.

Magnesium: An old player revisited in the context of CKD-MBD

Chronic kidney disease (CKD) is associated with a wide number of abnormalities in mineral metabolism. Often, these alterations are the leading players in the development of comorbidities associated with CKD, which are risk factors of mortality. In this context, mineral and bone disorder associated with CKD (CKD-MBD) are highlighted, connecting bone, renal, and cardiovascular disorders. Many studies have been led to propose strategies to avoid, reduce, or slow down CKD-MBD progression using different compositions of metallic elements-based P binders such as aluminum, magnesium, or calcium. Magnesium, the aim of this review, has been used by nephrologists to treat CKD-MBD with a variable acceptation due mainly to different results on bone homeostasis. Nowadays, we have new evidence about the efficacy of magnesium supplementation on vascular calcification, renal function, and bone disorders, suggesting potential beneficial effects of Magnesium in the management of CKD-MBD.

Correction of hypomagnesemia by dapagliflozin in patients with type 2 diabetes: A post hoc analysis of 10 randomized, placebo-controlled trials

AIMS

Hypomagnesemia (serum magnesium [Mg] <0.74 mmol/L [<1.8 mg/dL]) is commonly observed in patients with type 2 diabetes (T2D). This study investigated the effect of treatment with dapagliflozin 10 mg on Mg concentrations in patients with T2D.

METHODS

In this post hoc analysis, we used pooled data from 10 placebo-controlled studies of dapagliflozin over 24 weeks of treatment in patients with T2D. We evaluated the change in Mg in patients receiving dapagliflozin vs. placebo overall, and in subgroups with baseline hypomagnesemia and normal/hypermagnesemia (≥0.74 mmol/L [≥1.8 mg/dL]). We determined the proportion of patients with baseline hypomagnesemia who achieved Mg ≥0.74 mmol/L (≥1.8 mg/dL).

RESULTS

A total of 4398 patients with T2D were included. The mean change from baseline to week 24 in Mg was significantly larger with dapagliflozin vs. placebo; difference, 0.06 mmol/L (95% confidence interval [CI]: 0.05, 0.06). The proportion of patients with Mg within the population reference range after 24 weeks of treatment was significantly higher with dapagliflozin vs. placebo; difference, 47.8% (95% CI: 41.4, 53.9). The proportion of patients displaying hypermagnesemia did not increase with dapagliflozin treatment.

CONCLUSIONS

Treatment with dapagliflozin 10 mg resulted in correction of Mg concentrations in patients with T2D and hypomagnesemia.

Hypomagnesemia and Survival in Patients with Ovarian Cancer Who Received Chemotherapy with Carboplatin

BACKGROUND

Hypomagnesemia is a known side effect of several antineoplastic agents, but its impact on outcomes of patients with cancer is not well understood. We examined whether magnesium abnormalities affect survival in patients with ovarian cancer who receive chemotherapy containing carboplatin.

MATERIALS AND METHODS

We included patients with advanced ovarian cancer who had undergone surgery and chemotherapy between January 1, 2004, and December 31, 2014, at our institution. Inclusion criteria were age 18 years or older, pathology of high-grade serous carcinoma, first treatment (surgery or chemotherapy) within 60 days of diagnosis, and chemotherapy containing carboplatin. The final cohort consisted of 229 patients. Vital signs and laboratory tests were recorded at baseline and during the treatment course. The associations between magnesium abnormalities (and other clinical characteristics) and survival were analyzed.

RESULTS

The median patient age was 64 years. Higher baseline heart rate (beats per minute; hazard ratio [HR] = 1.02, p = .002) and greater frequency of hypomagnesemia during the treatment course (HR = 1.05, p = .002) were significantly associated with shorter survival independent of completeness of tumor reduction (HR = 1.60, p = .02), and International Federation of Gynecology and Obstetrics stage (HR = 1.63, p = .01).

CONCLUSION

Baseline heart rate and the frequency of hypomagnesemia episodes during treatment are prognostic of survival for patients with advanced ovarian cancer receiving carboplatin-containing chemotherapy and tumor reductive surgery. Future research is needed for strategies to detect and prevent hypomagnesemia in this patient population.

IMPLICATIONS FOR PRACTICE

Despite standard laboratory tests and intravenous magnesium replacement prior to each cycle of chemotherapy, hypomagnesemia remains a common side effect of platinum-based chemotherapy. This study revealed that frequent occurrence of hypomagnesemia during the course of treatment including carboplatin-containing chemotherapy and tumor reductive surgery was strongly predictive of shorter survival in patients with advanced ovarian cancer. Strategies to effectively mitigate hypomagnesemia, such as more frequent detection, dietary recommendations, and timely replacement, should be considered in the overall cancer treatment plan for these patients.

Amelioration of thyroid dysfunction by magnesium in experimental diabetes may also prevent diabetes-induced renal impairment

Background

Diabetes mellitus has been reported to cause thyroid dysfunction, which may also impair renal function. Magnesium has been reported to exert ameliorative effects in diabetes mellitus. This study investigated thyroid and renal functions in experimental type-2-diabetic Wistar rats.

Methods

Experimental type-2-diabetes was induced using short duration high-fat (30%) diet feeding followed by single-dose streptozotocin (35 mg/kg i.p.). Fifty rats were randomly divided into five equal groups consisting of control, diabetes untreated, diabetes treated with either magnesium (250 mg/kg) or metformin (250 mg/kg) and diabetes treated with both metformin and magnesium simultaneously.

All treatments were carried out orally for 14days post-diabetes induction. Body weight and blood glucose was monitored using the tail tipping method before diabetes induction and thereafter on days 1,7,14 post-treatment respectively. Thereafter, blood samples were collected by cardiac puncture after light anesthesia into plain and EDTA sample bottles. Total protein, albumin, globulin (plasma) and insulin (serum) were assayed in all samples obtained. Thyroid stimulating hormone (TSH), triiodothyronine, thyroxine was also evaluated (n = 5/group) in serum while blood urea nitrogen (BUN), creatinine was assessed (n = 5/group) in plasma. Kidney homogenates were obtained per group and analyzed for renal superoxide dismutase (SOD), reduced glutathione (GSH) and lipid peroxidation (MDA). Kidney histology was also evaluated per group using both Haematoxylin and Eosin and periodic acid Schiff stains.

Results

Body weight, blood glucose, insulin, renal MDA was increased in diabetic untreated compared to other groups. Reductions (P < 0.05) in TSH, triiodothynine, Renal SOD and GSH levels where observed in diabetic untreated compared to other groups. Renal histology in diabetic untreated showed glomerula sclerosis, fused messengial cells and either collapsed tubular lumen or lumen with eosinophilic renal cast. These pathologies where partially reversed in the other experimental groups.

Conclusion

This study suggests that thyroid and renal impairment may be present in experimental type-2-diabetes. Treatment with oral magnesium may cause a partial restoration of thyroid function that may impede the development of renal dysfunction.

Renal phospholipidosis and impaired magnesium handling in high-fat-diet-fed mice

Hypomagnesemia (blood Mg²⁺ concentration <0.7 mM) is a common electrolyte disorder in patients with type 2 diabetes (T2D), but the etiology remains largely unknown. In patients with T2D, reduced blood Mg²⁺ levels are associated with an increased decline in renal function, independent of glycemic control and hypertension. To study the underlying mechanism of this phenomenon, we investigated the renal effects of hypomagnesemia in high-fat-diet (HFD)-fed mice. In mice fed a low dietary Mg²⁺, the HFD resulted in severe hypomagnesemia within 4 wk. Renal or intestinal Mg²⁺ wasting was not observed after 16 wk on the diets. Despite the absence of urinary or fecal Mg²⁺ loss, the HFD induced a reduction in the mRNA expression transient receptor potential melastatin type 6 in both the kidney and colon. mRNA expression of distal convoluted tubule (DCT)-specific genes was down-regulated by the LowMg-HFD, indicating atrophy of the DCT. The low dietary Mg²⁺ resulted in severe HFD-induced proximal tubule phospholipidosis, which was absent in mice on a NormalMg-HFD. This was accompanied by albuminuria, moderate renal damage, and alterations in renal energy metabolism, including enhanced gluconeogenesis and cholesterol synthesis. In conclusion, this study shows that hypomagnesemia is a consequence of diet-induced obesity and insulin resistance. Moreover, hypomagnesemia induces major structural changes in the diabetic kidney, including proximal tubular phospholipidosis, providing a novel mechanism for the increased renal decline in patients with hypomagnesemic T2D.-Kurstjens, S., Smeets, B., Overmars-Bos, C., Dijkman, H. B., den Braanker, D. J. W., de Bel, T., Bindels, R. J. M., Tack, C. J. J., Hoenderop, J. G. J., de Baaij, J. H. F. Renal phospholipidosis and impaired magnesium handling in high-fat-diet-fed mice.

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.

Diabetes-induced hypomagnesemia is not modulated by metformin treatment in mice

Approximately 30% of patients with type 2 diabetes mellitus (T2D) have hypomagnesemia (blood magnesium (Mg²⁺) concentration <0.7 mmol/L). In T2D patients, treatment with metformin is associated with reduced blood Mg²⁺ levels. To investigate how T2D and metformin affect Mg²⁺ homeostasis db/m and db/db mice were treated with metformin or placebo. Mice were housed in metabolic cages to measure food and water intake, and to collect urine and feces. Serum and urinary Mg²⁺ concentrations were determined and mRNA expression of magnesiotropic genes was determined in kidney and distal colon using RT-qPCR. Db/db mice had significantly lower serum Mg²⁺ levels than db/m mice. Mild hypermagnesuria was observed in the db/db mice at two weeks, but not at four weeks. Metformin-treatment had no effect on the serum Mg²⁺ concentration and on the urinary Mg²⁺ excretion. Both in kidney and distal colon of db/db mice, there was a compensatory upregulation in the mRNA expression of magnesiotropic genes, such as transient receptor potential melastatin 6 (Trpm6), whereas metformin treatment did not affect gene expression levels. In conclusion, we show that T2D causes hypomagnesemia and that metformin treatment has no effect on Mg²⁺ homeostasis in mice.

Increased NEFA levels reduce blood Mg2+ in hypertriacylglycerolaemic states via direct binding of NEFA to Mg2

AIMS/HYPOTHESIS

The blood triacylglycerol level is one of the main determinants of blood Mg2+ concentration in individuals with type 2 diabetes. Hypomagnesaemia (blood Mg2+ concentration <0.7 mmol/l) has serious consequences as it increases the risk of developing type 2 diabetes and accelerates progression of the disease. This study aimed to determine the mechanism by which triacylglycerol levels affect blood Mg2+ concentrations.

METHODS

Using samples from 285 overweight individuals (BMI >27 kg/m2) who participated in the 300-Obesity study (an observational cross-sectional cohort study, as part of the Human Functional Genetics Projects), we investigated the association between serum Mg2+ with laboratory variables, including an extensive lipid profile. In a separate set of studies, hyperlipidaemia was induced in mice and in healthy humans via an oral lipid load, and blood Mg2+, triacylglycerol and NEFA concentrations were measured using colourimetric assays. In vitro, NEFAs harvested from albumin were added in increasing concentrations to several Mg2+-containing solutions to study the direct interaction between Mg2+ and NEFAs.

RESULTS

In the cohort of overweight individuals, serum Mg2+ levels were inversely correlated with triacylglycerols incorporated in large VLDL particles (r = -0.159, p ≤ 0.01). After lipid loading, we observed a postprandial increase in plasma triacylglycerol and NEFA levels and a reciprocal reduction in blood Mg2+ concentration both in mice (Δ plasma Mg2+ -0.31 mmol/l at 4 h post oral gavage) and in healthy humans (Δ plasma Mg2+ -0.07 mmol/l at 6 h post lipid intake). Further, in vitro experiments revealed that the decrease in plasma Mg2+ may be explained by direct binding of Mg2+ to NEFAs. Moreover, Mg2+ was found to bind to albumin in a NEFA-dependent manner, evidenced by the fact that Mg2+ did not bind to fatty-acid-free albumin. The NEFA-dependent reduction in the free Mg2+ concentration was not affected by the presence of physiological concentrations of other cations.

CONCLUSIONS/INTERPRETATION

This study shows that elevated NEFA and triacylglycerol levels directly reduce blood Mg2+ levels, in part explaining the high prevalence of hypomagnesaemia in metabolic disorders. We show that blood NEFA level affects the free Mg2+ concentration, and therefore, our data challenge how the fractional excretion of Mg2+ is calculated and interpreted in the clinic.

Summary of the 2018 ISN Frontiers Meeting: Kidney Disease and Cardiovascular Disease

International Society of Nephrology (ISN) Frontiers meetings build on the success of the ISN Nexus and Forefronts series by bringing together basic scientists, clinicians, and practitioners in a unique setting. This new event was organized to make more innovative science available to a global audience by removing regional barriers in accessing the latest knowledge. The first ISN Frontiers meeting was organized in partnership between the Japanese Society of Nephrology and the Japanese Society for Dialysis Therapy, which was held in Tokyo in February 2018. The meeting focused on the topic “Kidney Disease & Cardiovascular Disease,” which covered a broad range of scientific and clinical fields, including nephrology, cardiovascular diseases, dialysis, transplantation, chronic kidney disease (CKD)–mineral bone disease (MBD), diabetes, pediatric nephrology, nutrition, pharmacology, and nursing. A total of 1584 active physicians and scientists from 64 countries attended the meeting, and a number of leading physician scientists from different and related disciplines of clinical and basic research described and reviewed recent discoveries. This report summarizes the main highlights of the meeting lectures.

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.

Magnesium and Progression of Chronic Kidney Disease: Benefits Beyond Cardiovascular Protection?

Experimental and clinical studies have demonstrated that magnesium deficiency leads to hypertension, insulin resistance, and endothelial dysfunction, and is associated with an increased risk of cardiovascular events. Given that cardiovascular disease and CKD share similar risk factors, the low magnesium status may also contribute to CKD progression. In fact, lower serum magnesium levels and lower dietary magnesium intake are associated with an increased risk of incident CKD and progression to end-stage kidney disease. Because these associations are independent of traditional risk factors, other pathways might be involved in the relationship between magnesium deficiency and the risk of CKD progression. Recent evidence has shown that magnesium suppresses phosphate-induced vascular calcification. Magnesium impairs the crystallization of calcium phosphate-more specifically, the maturation of calciprotein particles. Considering that phosphate overload causes kidney damage, magnesium might counteract the phosphate toxicity to the kidney, as in the case of vascular calcification. This hypothesis is supported by an in vitro observation that magnesium alleviates proximal tubular cell injury induced by high phosphate. Potential usefulness of magnesium as a treatment option for phosphate toxicity in CKD should be further investigated by intervention studies.

Prognostic importance of plasma total magnesium in a cohort of cats with azotemic chronic kidney disease

Background

Hypomagnesemia is associated with increased mortality and renal function decline in humans with chronic kidney disease (CKD). Magnesium is furthermore inversely associated with fibroblast growth factor 23 (FGF23), an important prognostic factor in CKD in cats. However, the prognostic significance of plasma magnesium in cats with CKD is unknown.

Objectives

To explore associations of plasma total magnesium concentration (tMg) with plasma FGF23 concentration, all‐cause mortality, and disease progression in cats with azotemic CKD.

Animals

Records of 174 client‐owned cats with IRIS stage 2‐4 CKD.

Methods

Cohort study. Cats with azotemic CKD were identified from the records of two London‐based first opinion practices (1999–2013). Possible associations of baseline plasma tMg with FGF23 concentration and risks of death and progression were explored using, respectively, linear, Cox, and logistic regression.

Results

Plasma tMg (reference interval, 1.73–2.57 mg/dL) was inversely associated with plasma FGF23 when controlling for plasma creatinine and phosphate concentrations (partial correlation coefficient, −0.50; P < .001). Hypomagnesemia was observed in 12% (20/174) of cats, and independently associated with increased risk of death (adjusted hazard ratio, 2.74; 95% confidence interval [CI], 1.35–5.55; P = .005). The unadjusted associations of hypermagnesemia (prevalence, 6%; 11/174 cats) with survival (hazard ratio, 2.88; 95% CI, 1.54–5.38; P = .001), and hypomagnesemia with progressive CKD (odds ratio, 17.7; 95% CI, 2.04–154; P = .009) lost significance in multivariable analysis.

Conclusions and Clinical Importance

Hypomagnesemia was associated with higher plasma FGF23 concentrations and increased risk of death. Measurement of plasma tMg augments prognostic information in cats with CKD, but whether these observations are associations or causations warrants further investigation.

Association of proton pump inhibitor use with the risk of the development or progression of albuminuria among Japanese patients with diabetes: A prospective cohort study [Diabetes Distress and Care Registry at Tenri (DDCRT 16)]

AIMS

We aimed to determine the prospective association between proton pump inhibitor (PPI) use and the subsequent risk of the development or progression of albuminuria or eGFR.

METHODS

Longitudinal data of patients with diabetes were obtained from a large Japanese diabetes registry. To assess the independent correlation between PPI use and the development or progression of urine microalbuminuria, the time-varying Cox proportional hazards model was used with adjustment for potential confounders.

RESULTS

The mean patient age, body-mass index (BMI), and hemoglobin A1c (HbA1c) levels were 65.7 y, 24.5 kg/m², and 7.5% (57.9 mmol/mol), respectively. In 1711 patients without albuminuria, we observed 599 cases with development of albuminuria over median follow-up of 4.0 years, and in 1279 patients with microalbuminuria, 290 cases with urinary albuminuria progression over 4.0 years, and 257 eGFR decline cases over 3.8 years. PPI use was not associated with the development of albuminuria (HR = 0.88; 95%CI, 0.77-1.01; p = .058), progression of albuminuria (HR = 1.24; 95%CI, 0.87-1.79; p = .236), nor eGFR decline (HR = 1.05; 95%CI, 0.81-1.34; p = .973) even in a propensity score-adjusted model with time-varyingly updating PPI use information.

CONCLUSIONS

In conclusion, PPI use was not associated with the subsequent risk of development or progression of albuminuria, or eGFR decline in patients with diabetes.

Increased circulating magnesium concentrations after Roux-en-Y gastric bypass surgery in patients with type 2 diabetes

BACKGROUND

Low circulating magnesium concentrations predict cardiovascular and all-cause mortality in patients with type 2 diabetes (T2D). Epidemiologic and clinical studies have indicated lower extra- and intracellular magnesium concentrations in patients with diabetes.

OBJECTIVE

We aimed to describe alterations, if any, in circulating magnesium concentrations after laparoscopic Roux-en-Y gastric bypass surgery (LRYGB) in patients with obesity and T2D.

SETTING

Outpatient clinic of obesity and central hospital.

METHODS

Retrospective analysis of 1-year outcome of plasma magnesium (p-Mg) and glucometabolic status in all consecutive patients who underwent primary LRYGBP and who completed the follow-up visits, including biochemical test panels 6 and 12 months after surgery.

RESULTS

LRYGBP and complete follow-up visits were performed in 51 patients with T2D and 86 patients without T2D. All patients were given similar dietary advice and multivitamin and mineral supplementation after surgery. Before RYGB, the patients with T2D showed lower p-Mg compared with patients without T2D (.79 ± .06 mM and .82 ± .05 mM, respectively, P<.01). P-Mg was inversely correlated to fasting blood glucose and glycosylated hemoglobin levels. After surgery, mean p-Mg increased by 5.2% in the group with T2D compared with 1.4% in the patients without T2D (P<.01), ending at an equal level of .83 mM. The alterations in p-Mg were inversely related to the changes in fasting glucose and glycosylated hemoglobin concentrations.

CONCLUSION

The lowered p-Mg associated with impaired glucometabolic status in patients with T2D was increased after LRYGBP, reaching similar concentrations as in patients without T2D.

Magnesium Replacement Improves the Metabolic Profile in Obese and Pre-Diabetic Patients with Mild-to-Moderate Chronic Kidney Disease: A 3-Month, Randomised, Double-Blind, Placebo-Controlled Study

BACKGROUND/AIMS

Magnesium is an essential mineral for many metabolic functions. There is very little information on the effect of magnesium supplementation on metabolic profiles of chronic kidney disease (CKD) patients. The aim of this study was to assess the influence of magnesium supplementation on metabolic profiles of pre-diabetic, obese and mild-to-moderate CKD patients with hypomagnesemia.

METHODS

A total of 128 hypomagnesemic, pre-diabetic and obese patients with an estimated glomerular filtration rate between 90 and 30 ml/min/1.73m2 were enrolled in a randomised, double-blind, placebo-controlled trial. Patients in the magnesium group received 365 mg of oral magnesium (n = 57) once daily for 3 months, while patients in the control group received a placebo (n = 61), also once daily for 3 months. Hypomagnesemia is defined by a serum magnesium level <1.8 mg/dl in males and <1.9 mg/dl in females; obesity is defined as a body mass index ≥30 kg/m2; and pre-diabetes is defined as fasting plasma glucose ≥100 but <126 mg/dl. The primary end point of the study was the change in insulin resistance measured by the homeostastic model assessment for insulin resistance (HOMA-IR).

RESULTS

At the end of follow-up, insulin resistance (-24.5 vs. -8.2%, P = 0.007), HOMA-IR index (-31.9 vs. -3.3%, P < 0.001), hemoglobin A1c (-6.6 vs. -0.16%, P < 0.001), insulin (-29.6 vs. -2.66%, P < 0.001), waist circumference (-4.8 vs. 0.55%, P < 0.001) and uric acid (-0.8 vs. 2.2%, P = 0.004) were significantly decreased in terms of mean changes; albumin (0.91 vs. -2.91%, P = 0.007) and magnesium (0.21 ± 0.18 vs. -0.04 ± 0.05 mg/dl, P < 0.001) were significantly increased in those taking magnesium compared with a placebo. The decrease in metabolic syndrome (-10.5 vs. -4.9%, P = 0.183), obesity (-15.7 vs. -8.2%, P = 0.131), pre-diabetes (-17.5 vs. -9.8%, P = 0.140), and systolic (-5.0 ± 14.8 vs. 0.22 ± 14.9 mm Hg, P = 0.053) and diastolic (-3.07 ± 9.7 vs. 0.07 ± 9.6 mm Hg, P = 0.071) blood pressure did not achieve to a significant level after study.

CONCLUSION

Our data support the argument that magnesium supplementation improves the metabolic status in hypomagnesemic CKD patients with pre-diabetes and obesity.

Magnesium Replacement to Protect Cardiovascular and Kidney Damage? Lack of Prospective Clinical Trials

Patients with advanced chronic kidney disease exhibit an increase in cardiovascular mortality. Recent works have shown that low levels of magnesium are associated with increased cardiovascular and all-cause mortality in hemodialysis patients. Epidemiological studies suggest an influence of low levels of magnesium on the occurrence of cardiovascular disease, which is also observed in the normal population. Magnesium is involved in critical cellular events such as apoptosis and oxidative stress. It also participates in a number of enzymatic reactions. In animal models of uremia, dietary supplementation of magnesium reduces vascular calcifications and mortality; in vitro, an increase of magnesium concentration decreases osteogenic transdifferentiation of vascular smooth muscle cells. Therefore, it may be appropriate to evaluate whether magnesium replacement should be administered in an attempt to reduce vascular damage and mortality in the uremic population In the present manuscript, we will review the magnesium homeostasis, the involvement of magnesium in enzymatic reactions, apoptosis and oxidative stress and the clinical association between magnesium and cardiovascular disease in the general population and in the context of chronic kidney disease. We will also analyze the role of magnesium on kidney function. Finally, the experimental evidence of the beneficial effects of magnesium replacement in chronic kidney disease will be thoroughly described.