From the Guidelines
Chronic hypomagnesemia has severe consequences on morbidity, mortality, and quality of life, leading to neuromuscular, cardiovascular, and metabolic complications, and should be treated promptly with oral magnesium supplements, such as magnesium oxide 12-24 mmol daily, as recommended by the most recent guidelines 1. The effects of chronic hypomagnesemia are multifaceted, affecting various bodily systems. Neuromuscular symptoms include tremors, muscle cramps, tetany, and seizures due to increased neuronal excitability. Cardiovascular manifestations include arrhythmias, hypertension, and increased risk of coronary artery disease. Metabolically, hypomagnesemia causes hypocalcemia and hypokalemia that resist correction until magnesium is repleted, as magnesium is needed for proper calcium regulation and potassium channel function. It contributes to insulin resistance and can worsen diabetes control. Chronic low magnesium also weakens bones by affecting parathyroid hormone secretion and vitamin D metabolism, potentially leading to osteoporosis. Psychiatric symptoms like anxiety, depression, and cognitive changes may occur.
Treatment and Management
Treatment requires identifying and addressing the underlying cause (such as medications, malabsorption, or alcoholism) while supplementing with oral magnesium. The most effective treatment, according to the latest evidence 1, involves oral magnesium oxide 12-24 mmol daily. Severe cases may require IV magnesium sulfate. Dietary changes to include magnesium-rich foods like leafy greens, nuts, seeds, and whole grains are also important for long-term management. It is essential to monitor serum calcium levels when using oral 1-alpha hydroxy-cholecalciferol to improve magnesium balance, as recommended by earlier guidelines 1.
Key Considerations
- Magnesium deficiency is common and has been associated with poor prognosis in cardiac arrest patients 1.
- Magnesium levels of 2.5 to 5 mmol/L may manifest as prolonged PR, QRS, and QT intervals; severely elevated levels of 6 to 10 mmol/L may result in atrioventricular nodal conduction block, bradycardia, hypotension, and cardiac arrest 1.
- The use of electrocardiographic monitoring among hospitalized patients with moderate and severe imbalances of potassium or magnesium facilitates the use of published algorithms to prevent or intervene for lethal cardiac rhythms 1.
From the Research
Effects of Chronic Hypomagnesemia
The effects of chronic hypomagnesemia (low magnesium levels) can be severe and potentially fatal if not timely diagnosed and properly treated 2. Some of the key effects include:
- Secondary hypokalemia and hypocalcemia
- Severe neuromuscular and cardiovascular clinical manifestations
- Increased mortality
Associated Chronic Diseases
Chronic low magnesium state has been associated with a number of chronic diseases, including:
- Diabetes 3, 4, 5
- Hypertension 3, 4, 5
- Coronary heart disease 3, 4
- Osteoporosis 3
- Alzheimer's disease 5
- Insulin resistance and type-2 diabetes mellitus 5
- Cardiovascular disease (e.g., stroke) 5
- Migraine headaches 5
- Attention deficit hyperactivity disorder (ADHD) 5
Mechanisms and Pathobiology
The mechanisms by which magnesium deficiency plays detrimental roles in cardiovascular diseases are complex and involve:
- Neuronal sources of the neuropeptide, substance P (SP), contributing to early prooxidant/proinflammatory changes during Mg deficiency 6
- Systemic neurogenic inflammation affecting blood cells, cardiovascular, intestinal, and other tissues 6
- Impaired cardiac contractility similar to that seen in patients with heart failure 6
Clinical Implications
The clinical implications of chronic hypomagnesemia are significant, and patients at risk of Mg deficiency should be considered for treatment even with serum Mg within the normal range 2. Additionally, treating Mg deficiency may help prevent cardiovascular disease 4.