Impact of Dysmagnesemia on Atrial Fibrillation in Maintenance Hemodialysis Patients: A Nationwide Study

INTRODUCTION

The dose-response relationship between serum magnesium (sMg) and atrial fibrillation (AF) and the contribution of dysmagnesemia to AF among hemodialysis patients remain unknown. Hence, we examined the dose-response correlation between sMg and AF and estimated the extent of the contribution of dysmagnesemia to AF in this population.

METHODS

This was a nationwide cross-sectional study on the Japanese Society for Dialysis Therapy registry, also known as Japanese Renal Data Registry (JRDR), encompassing a nationwide population of dialysis centers, as of the end of 2019. Eligible participants were adult patients undergoing hemodialysis three times per week. The main exposure was sMg, categorized into seven categories (≤1.5, >1.5-≤2, >2-≤2.5, >2.5-≤3, >3-≤3.5, >3.5-≤4, and ≥4.0 mg/dL). The outcome was AF reported by dialysis facilities. The independent contribution to AF was assessed via logistic regression to generate population-attributable fractions, assuming a causal relationship between sMg and AF.

RESULTS

Total 165,926 patients from 2,549 facilities were investigated. AF prevalence was 7.9%. Compared with the reference (>2.5-≤3 mg/dL), lower sMg was associated with increased AF (adjusted odds ratios (ORs) (95% confidence interval, CI) of 1.49 (1.19-1.85), 1.24 (1.17-1.32), and 1.11 (1.06-1.16) for sMg of ≤1.5, >1.5-≤2.0, and >2.0-≤2.5 mg/dL categories, respectively). Elevated sMg was associated with fewer AF (adjusted OR 0.87 [95% CI, 0.79-0.96] for sMg of >3.0-≤3.5 mg/dL). The adjusted population-attributable fraction of lower sMg and higher and lower sMg for AF was 7.4% and 6.9%, respectively. An association did indeed exist between lower sMg and AF, with the lowest percentages of AF at sMg levels above the reference range for the general population.

CONCLUSION

Dysmagnesemia may be an important contributor to AF among adult hemodialysis patients. Further, longitudinal studies are warranted to determine whether sMg correction reduces the AF incidence.

Ionized or Total Magnesium levels, what should we measure in critical ill patients?

Monitoring and measuring magnesium (Mg) values are essential to prevent the development of numerous complications in perioperative medicine and critically ill patients. Although previous studies suggest that measuring free ionized magnesium (iMg) is more useful for estimating Mg status, clinicians currently rely on measurement of total serum magnesium to determine if supplemental magnesium is needed. In this review, we analyzed the recent literature to decide whether it is better to measure ionized serum Mg or total serum Mg when assessing magnesium status, whether iMg predicts clinical outcome, and what are the difficulties in measuring serum iMg levels in intensive care patients and perioperative medicine.

Acid-Base and Electrolyte Disorders in Patients with and without Chronic Kidney Disease: An Update

Kidneys play a pivotal role in the maintenance and regulation of acid-base and electrolyte homeostasis, which is the prerequisite for numerous metabolic processes and organ functions in the human body. Chronic kidney diseases compromise the regulatory functions, resulting in alterations in electrolyte and acid-base balance that can be life-threatening. In this review, we discuss the renal regulations of electrolyte and acid-base balance and several common disorders including metabolic acidosis, alkalosis, dysnatremia, dyskalemia, and dysmagnesemia. Common disorders in chronic kidney disease are also discussed. The most recent and relevant advances on pathophysiology, clinical characteristics, diagnosis, and management of these conditions have been incorporated.

Genetics of Magnesium Disorders

Background

Magnesium (Mg²⁺), the second most abundant cation in the cell, is woven into a multitude of cellular functions. Dysmagnesemia is associated with multiple diseases and, when severe, can be life-threatening.

Summary

This review discusses Mg²⁺ homeostasis and function with specific focus on renal Mg²⁺ handling. Intrarenal channels and transporters related to Mg²⁺ absorption are discussed. Unraveling the rare genetic diseases with manifestations of dysmagnesemia has greatly increased our understanding of the complex and intricate regulatory network in the kidney, specifically, functions of tight junction proteins including claudin-14, -16, -19, and -10; apical ion channels including: TRPM6, K_v1.1, and ROMK; small regulatory proteins including AC3 and ANK3; and basolateral proteins including EGF receptor, γ-subunit (FXYD2) of Na-K-ATPase, K_ir4.1, CaSR, CNNM2, and SLC41A. Although our understanding of Mg²⁺ handling of the kidney has expanded considerably in the last two decades, many questions remain. Future studies are needed to elucidate a multitude of unknown aspects of Mg²⁺ handling in the kidney.

Key Message

Understanding rare and genetic diseases of Mg²⁺ dysregulation has expanded our knowledge and furthers the development of strategies for preventing and managing dysmagnesemia.