Physiological Role of Magnesium in the Body
Magnesium is a vital macromineral absolutely essential for maintaining normal cellular activity. First and foremost, it is required for glycolysis. In addition, magnesium is a structural component of thirteen different metalloproteins and acts as a cofactor for more than two hundred enzymes, ensuring their biological activity.
Of particular importance is the physiological effect of magnesium in the nervous system. This ion possesses pronounced neurosedative properties. In a healthy organism, it functions as a unique natural "insulator" situated along the pathway of nerve impulse conduction, thereby preventing excessive excitability of nervous tissue.
Etiology: Why Does Magnesium Level Rise?
The development of hypermagnesemia is associated with an imbalance between the intake, distribution, and excretion of this ion. There are three main groups of causes:
- Decreased renal excretion of magnesium. This is a consequence of impaired renal excretory function. This mechanism is primary in pathologies such as chronic diffuse glomerulonephritis, various nephroses, pyelonephritis, and renal failure. When the kidneys lose their ability to adequately filter blood, magnesium begins to accumulate in the body.
- Excessive external intake of magnesium. Most commonly, this is an iatrogenic cause. It occurs with the intake of high doses of magnesium-containing medications (e.g., laxatives or magnesium oxide). A sharp spike in magnesium levels is also possible with intravenous administration of its salts, which is frequently practiced in the management of preeclampsia.
- Redistribution of magnesium from cells. Normally, magnesium is predominantly intracellular. However, under certain pathological conditions, it begins to shift into the extracellular fluid and blood. This pathological shift is characteristic of chronic acidosis (often accompanying diabetes mellitus) and hypothyroidism.
Pathogenesis and Clinical Manifestations
The fundamental basis of all symptoms in hypermagnesemia is inhibition of neuromuscular transmission, leading to a global decrease in nerve and muscle excitability.
The ionic mechanism of this inhibition consists of a severe electrolyte imbalance: there is a pathological decrease in the intracellular content of potassium (K+) and calcium (Ca2+) ions. Simultaneously, their levels, along with the concentration of magnesium itself (Mg2+), increase in the extracellular fluid.
This imbalance forms four main clinical syndromes:
- Depression of higher nervous activity (HNA). Due to a gross disruption of transmembrane ion distribution, brain functions are suppressed. In severe cases, the condition progresses to complete loss of consciousness, leading to so-called "magnesium coma/sleep."
- Alveolar hypoventilation. Excess magnesium causes a decrease in the activity of respiratory center neurons, leading to respiratory depression.
- Muscle hypotonia and hypokinesia. Decreased excitability affects not only skeletal muscles but also the smooth muscle of internal organs (particularly affecting the gastrointestinal tract).
- Arterial hypotension. Suppression of nerve impulses naturally leads to a drop in blood pressure.
Principles of Hypermagnesemia Management
Treatment of this electrolyte disorder requires a comprehensive approach and always begins with treating the underlying disease that caused it.
The second crucial stage is eliminating the cause of hypermagnesemia. To achieve this, it is necessary to:
- Provide adequate management of renal failure.
- Correct metabolic shifts: compensate for hypothyroidism and correct chronic acidosis.
- Ensure cessation or strict limitation of the use of any magnesium-containing medications.