Hypermagnesemia : Causes, Symptoms, Diagnosis & Treatment

Last Updated: 19/07/2022

Hypermagnesemia is a pathological condition characterized by an increase in the concentration of magnesium in the blood serum of more than 1.1 mmol / l. The most common cause of this deviation is kidney disease with impaired excretory function, taking magnesium-containing drugs. Clinical manifestations include depression of the nervous system, decreased muscle tone and blood pressure. The level of magnesium is examined during a biochemical blood test. Treatment of this condition is to eliminate the cause, the introduction of calcium preparations, isotonic solutions and diuretics.

Magnesium is one of the main macroelements of the human body. Along with potassium, magnesium is located predominantly intracellularly. Mg is involved in maintaining the membrane potential, the transmission of nerve excitation in cells, and the activation of many enzymes. Together with calcium, magnesium regulates the processes of muscle contraction and relaxation. Also, this electrolyte is part of the bone tissue and ATP molecules - the main "energy carrier". Hypermagnesemia is predominantly found in patients with nephrological hospitals. Accurate information about the prevalence of this pathology is not available.

Causes of hypermagnesemia

Hypermagnesemia is a fairly rare violation of electrolyte metabolism. There are no physiological reasons for this laboratory phenomenon, so its detection always (with the exception of the drug form) indicates the presence of some kind of pathology. Etiological factors of hypermagnesemia:

  • Renal failure. The most common cause of an increase in the concentration of magnesium in the blood. About 80% of all Mg is removed from the body through the kidneys. Hypermagnesemia develops in the end stage of renal failure, when the glomerular filtration rate falls below 15 ml/min. Hypermagnesemia in acute renal failure is possible, but much less common.
  • Taking medications. To hypermagnesemia leads to the intake of a large number of drugs containing magnesium - magnesium oxide (antacid) for gastric ulcer and 12 duodenal ulcer, laxative enemas with magnesium for the treatment of constipation. The most pronounced hypermagnesemia occurs with parenteral administration of solutions with magnesium, as well as with long-term treatment of preeclampsia in pregnant women with magnesium sulfate (magnesium sulfate).
  • Diseases of the gastrointestinal tract. In some patients suffering from inflammatory diseases of the gastrointestinal tract (gastritis, enteritis, colitis), hypermagnesemia may occur due to increased absorption of magnesium.
  • Diabetic ketoacidosis. In ketoacidosis, there are two pathogenetic mechanisms that together lead to hypermagnesemia: an active exchange of hydrogen ions for magnesium ions in the distal tubules of the kidneys and a significant decrease in intravascular volume.
  • Other hormonal disorders. In some endocrine diseases, Mg excretion decreases and its redistribution between the intra- and extracellular space also occurs. These pathologies include hypothyroidism, hypocorticism (Addison's disease), hypoaldosteronism.

Pathogenesis

An increase in the concentration of magnesium in the serum most of all affects the nervous system. The transmission of nerve impulses is slowed down or blocked. In neuromuscular synapses, the release of the mediator acetylcholine is suppressed. The tone of skeletal muscles, vascular smooth muscles and myocardium decreases. The transmembrane distribution of potassium and calcium ions is disturbed.

All higher nervous activity is suppressed. The activity of neurons of the respiratory center weakens most of all, alveolar hypoventilation occurs. The synthesis of parathyroid hormone is inhibited, which leads to hypocalcemia. It also reduces the production of ATP molecules. As a result of slowing down the impulse transmission in the conduction system of the heart, the heart rate decreases.

hypermagnesemia

 

Symptoms of hypermagnesemia

Distinct clinical signs begin to appear at magnesium levels above 2 mmol/L. One of the earliest symptoms of a high magnesium concentration is the weakening or disappearance of deep tendon reflexes (knee, Achilles). Paresthesia of the face (feeling of crawling, tingling) is characteristic. Many patients experience nausea and vomiting. With the aggravation of hypermagnesemia, muscle weakness joins, the severity of which correlates with the level of Mg.

The inhibition of the functioning of the central nervous system is evidenced by the appearance of drowsiness, lethargy of the patient, deterioration in concentration. Patients may feel a slow heartbeat. Due to a decrease in blood pressure, dizziness, blurred vision, and possible loss of consciousness occur. Due to paralysis of the smooth muscles of the stomach and intestines, there is a feeling of heaviness, discomfort in the abdomen, sometimes patients complain of constipation.

Complications

Hypermagnesemia is characterized by a large number of adverse effects. The most common of these is a violation of breathing, which is associated with weakness of the respiratory muscles and inhibition of the nerve cells of the respiratory center. The resulting dysregulation of spontaneous autonomous breathing can cause it to stop, which often occurs during sleep.

A slowdown in the conduction of impulses to the heart muscle can lead to life-threatening cardiac arrhythmias up to asystole, a sharp decrease in cardiac output can lead to the development of collapse. Food may enter the respiratory tract (aspiration) due to difficulty swallowing. Extremely rarely, in isolated cases, there is a "magnesian sleep" (coma) and dynamic intestinal obstruction.

Diagnostics

The profile of a specialist who supervises a patient with hypermagnesemia is determined by the pathology against which this condition developed. Most often, such patients are under the supervision of nephrologists. When collecting an anamnesis, the doctor clarifies whether a person has chronic diseases, is interested in what medications he takes.

During a general examination, attention is drawn to the level of consciousness, reaction to external stimuli, muscle hypotension and weakening of reflexes. Measured blood pressure, heart rate and respiratory movements at rest. To clarify the diagnosis, as well as for the differential diagnosis of the cause of hypermagnesemia, an additional examination is prescribed, including:

  • Laboratory research. To assess the excretory function of the kidneys in a biochemical blood test, the level of urea, creatinine is examined, the glomerular filtration rate is calculated using the Cockcroft-Gault and CKD-EPI formulas. For the diagnosis of kidney diseases in the general analysis of urine, protein concentration, relative density, the presence of erythrocytes, leukocytes are determined. With acute renal failure, markers of acute kidney injury, cystatin C and neutrophil-gelatinase-associated lipocaine (NGAL), will be elevated in the blood.
  • Gas and electrolyte composition of blood. In addition to magnesium, the level of other electrolytes is checked - potassium, calcium, sodium. If hypermagnesemia has developed against the background of ketoacidosis, the content of bicarbonates and chlorides is measured, the effective plasma osmolarity is calculated, and blood pH is studied.
  • Hormonal studies. If other endocrine diseases are suspected, the level of thyroid hormones (thyroxine, triiodothyronine), adrenal cortex (cortisol, aldosterone), pituitary gland (thyrotropic and adrenocorticotropic) is checked.
  • ECG. The electrocardiogram reveals a prolongation of the PR, QT interval, an expansion of the QRS complex, an increase in the amplitude of the T wave. Intra-atrial blockades are also noted. With extremely pronounced hypermagnesemia, atrioventricular blockades are found.

Determination of magnesium in blood plasma

 

Treatment of hypermagnesemia

Depending on the severity of hypermagnesemia and the patient's condition, treatment can take place both on an outpatient basis and in a hospital. For successful therapy, it is necessary to treat the underlying pathology. If an increase in the level of magnesium is provoked by taking medications, they must be urgently canceled. With a mild form, this is enough to quickly normalize Mg in the blood.

For the treatment of preeclampsia, pregnant women should replace magnesium sulfate with other antihypertensive drugs approved for use during pregnancy - nifedipine, methyldopa, metoprolol. In more severe situations, the following methods for eliminating hypermagnesemia are used:

  • Calcium preparations. Calcium, being a functional magnesium antagonist, is able to stop the most dangerous manifestations of excess magnesium - arrhythmias, respiratory depression. Calcium gluconate or calcium chloride is administered intravenously.
  • Forced diuresis. To accelerate the excretion of magnesium from the systemic circulation, infusions of isotonic sodium chloride solution and loop diuretics (furosemide) are prescribed.
  • Hemodialysis. In the case of severe hypermagnesemia, a rapid decrease in the concentration of Mg can be achieved by hemodialysis. Hemodialysis is the most optimal treatment option for hypermagnesemia in patients with terminal chronic renal failure.
  • Dealing with complications. With the development of respiratory failure, the patient is connected to a ventilator, with AV blockade of II and III degrees, a temporary pacemaker is installed through intravenous access.

Forecast and prevention

Severe hypermagnesemia is a serious pathological condition that, without timely medical intervention, can be fatal. The most common causes of death are respiratory arrest and cardiac arrhythmias. However, in most cases, the prognosis for this laboratory deviation is favorable and severe complications can almost always be avoided.

Prevention of hypermagnesemia consists in the timely diagnosis and treatment of those diseases that can serve as a background for its development. In patients with confirmed chronic renal failure, it is necessary to regularly monitor the level of magnesium, and also recommend avoiding the use of foods rich in magnesium (bananas, nuts).

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