Hypomagnesemia : Causes, Symptoms, Diagnosis & Treatment

• Causes Of Hypomagnesemia
• Risk Factors
• Pathogenesis
• Symptoms Of Hypomagnesemia
• Complications
• Diagnostics
• Treatment Of Hypomagnesemia
• Forecast And Prevention

Hypomagnesemia is a pathological condition that is characterized by a decrease in the concentration of magnesium in the blood below 0.6 mmol / l. This deviation can occur as a result of insufficient intake of magnesium in the body, with violations of its absorption in the digestive tract or excessive losses through the kidneys. The main clinical manifestations include increased neuromuscular excitability, disruption of the cardiovascular system, and changes in calcium metabolism. The level of magnesium is examined during a biochemical blood test. Treatment is carried out by the appointment of oral or parenteral forms of magnesium preparations.

Magnesium is one of the 4 major macronutrients in the human body. It is predominantly an intracellular cation. Mg is necessary for the functioning of about 30 different enzymes involved in glycolysis, transmembrane ion transport, protein synthesis, ATP, etc. Also, thanks to this electrolyte, the ability of nerve and muscle cells to excitability and conductivity is maintained. Hypomagnesemia occurs in approximately 12% of hospitalized patients, 60-65% of whom are intensive care patients. Hypomagnesemia is often associated with hypokalemia and hypocalcemia.

Causes of hypomagnesemia

There are many causes of hypomagnesemia. Benign and physiological etiological factors can be considered insufficient intake of magnesium from food, as well as emotional stress, pregnancy and lactation, when the need for magnesium increases. The causes of pathological hypomagnesemia are listed below:

• Diseases of the gastrointestinal tract. Pathologies of the gastrointestinal tract, accompanied by diarrhea and malabsorption, lead to loss of magnesium, as well as to a violation of its absorption. These include chronic pancreatitis, celiac disease, celiac disease, previous surgery with resection of the small intestine or gastro-iliac bypass.
• Chronic alcoholism. A fairly common cause of hypomagnesemia. In people who abuse alcohol for a long time, magnesium deficiency is formed by several mechanisms - suppression of Mg reabsorption in the renal tubules and absorption in the intestine by ethanol, poor and monotonous nutrition.
• Taking medications. Many drugs, acting on the tubules of the kidneys, can provoke a significant loss of Mg in the urine. These drugs include loop and thiazide diuretics (furosemide, hydrochlorothiazide), antibiotics from the aminoglycoside group (gentamicin), antifungals (amphotericin B), anticancer drugs (cisplatin). Proton pump inhibitors (omeprazole) and laxative drugs impair the absorption of magnesium in the gastrointestinal tract.
• Diseases of the kidneys. In some kidney diseases, the transport of many electrolytes through the renal tubules, including magnesium, is affected. These include interstitial nephritis, renal tubular acidosis, salt-losing kidney, congenital tubulopathies (Gitelman's syndrome, Bartter's syndrome).
• endocrine disorders. Hypomagnesemia can occur in diseases of the endocrine system: decompensated diabetes mellitus with high glycemia, hyperparathyroidism, primary hyperaldosteronism. With intensive treatment of diabetic ketoacidosis, there is a sharp movement of Mg ions from the interstitial space into the cells, which leads to hypomagnesemia.

Risk factors

Risk factors for hypomagnesemia include taking dietary supplements and multivitamin complexes, where magnesium, calcium and iron are simultaneously contained in one tablet or capsule. Ca and Fe compete with Mg for intestinal absorption. Rare causes of hypomagnesemia include:

• Familial renal magnesium deficiency.
• Genetic mutations of Na/K-ATPase.
• Mutation of hepatic nuclear factor 1β genes.
• Familial nephrocalcinosis.
• Sarcoidosis.
• Respiratory alkalosis.
• Undifferentiated connective tissue dysplasia.
• Refeeding syndrome (refeeding syndrome) after prolonged fasting.
• Hungry bones syndrome after surgical treatment of primary hyperparathyroidism (removal of parathyroid adenoma).

Determination of magnesium in blood plasma

Pathogenesis

As a result of a decrease in the concentration of magnesium in the plasma, the excitability of muscle and nerve cells increases. Involuntary muscle contractions are promoted by concomitant hypocalcemia, which occurs due to resistance of peripheral tissues to parathyroid hormone. Calcium channels are activated, Ca ions actively enter the smooth muscles of blood vessels and bronchi, which increases their tone (arterial hypertension, bronchoconstriction).

Myocardial hyperexcitability leads to an increase in heart rate, the appearance of extrasystoles. Due to the disruption of the functioning of magnesium-dependent enzymes, tissue degeneration develops. Due to the accelerated entry of calcium into tissues, their calcification is possible, especially in the vascular walls and nephron tubules.

Symptoms of hypomagnesemia

With a slight magnesium deficiency, there may be no symptoms. Before all, there are nonspecific complaints - general weakness, fatigue, combined with irritability. The most striking clinical signs are associated with increased neuromuscular excitability: there is a tremor, especially pronounced in the hands and tongue, involuntary muscle twitches (fasciculations), painful muscle spasms of the muscles of the extremities.

Excessive excitability of the cardiovascular system is manifested by an increase in heart rate, extrasystole, an increase in blood pressure - patients experience headaches, unpleasant sensations of interruptions in the work of the heart. In some patients, neuropsychiatric symptoms join - mood changes, apathy, anxiety-depressive states.

Due to spasms in the gastrointestinal tract, abdominal pain, nausea and vomiting can be disturbing. With a deep magnesium deficiency, especially in early childhood, there may be impaired coordination of movements, nystagmus, generalized tonic-clonic convulsions. Extremely rarely there are psychoses, erosions and ulcers on the skin.

Complications

Serious life-threatening complications with hypomagnesemia develop infrequently. The most dangerous is atrial fibrillation, which can significantly improve hemodynamics and contribute to the formation of blood clots in the heart chambers. In addition, hypomagnesemia increases the toxic effect of cardiac glycosides on the myocardial conduction system.

Due to an increase in the tone of the bronchi and blood vessels, magnesium deficiency can worsen the course of hypertension, bronchial asthma, and also increase the severity of migraine headaches. During pregnancy, severe magnesium deficiency can provoke premature birth and spontaneous miscarriage. With a long course of hypomagnesemia in children, growth retardation is observed.

Diagnostics

Due to the wide range of causes that cause hypomagnesemia, gastroenterologists, narcologists, nephrologists, etc. can deal with such patients. When collecting an anamnesis, it is necessary to specify which medications the patient is taking. During physical examination, attention is drawn to the objective signs of chronic alcoholism (nasal hyperemia, palmar erythema, telangiectasias), hyperreflexia, muscle spasms.

Latent tetany can be detected using tests for the Chvostek symptom (involuntary contraction of facial muscles when a neurological hammer is tapped on the facial nerve) and Trousseau (the occurrence of spasm in the muscles of the hand when the shoulder is compressed with a tonometer cuff). To clarify the diagnosis and differential diagnosis of the cause of hypomagnesemia, the following examination is prescribed:

• Identification of magnesium deficiency. The level of Mg is determined in the blood plasma. It should be borne in mind that normomagnesemia in the blood is possible with its true deficiency in the body. In such cases, a load test is performed - the patient is given 4 g of MgSO4 dissolved in 5% glucose, magnesiumuria less than 15 mmol / l indicates a deficiency. Urinary filtered Mg (FEMg) excretion is calculated to differentiate between renal and extrarenal magnesium loss.
• Blood chemistry. In persons with kidney disease or taking nephrotoxic drugs in the blood, an increase in the content of creatinine, urea is found, in chronic alcoholism - an increase in hepatic transaminases, gamma-glutamyl transpeptidase, carbohydrate-deficient transferrin (CDT).
• Determination of other electrolytes. In addition to hypomagnesemia, patients almost always have a low concentration of calcium and potassium in the blood.
• Stool analyses. In chronic pancreatitis, the coprogram reveals signs of exocrine pancreatic insufficiency - amylorrhea, steatorrhea, creatorrhea, and a decrease in the level of pancreatic elastase. In inflammatory bowel disease, the content of fecal calprotectin is increased in feces.
• Hormonal studies. If there are suspicions of endocrine pathology, the degree of glycemia, glucosuria, indicators of glycated hemoglobin, parathyroid hormone, renin-aldosterone ratio are determined.
• ECG. The electrocardiogram reveals prolongation of the QT interval, flattening of the T wave, the appearance of an abnormal U wave, atrial and ventricular extrasystoles, and atrial fibrillation.
• ultrasound. When conducting ultrasound of the abdominal organs in people with chronic pancreatitis, an increase in the size of the pancreas, a decrease in its echogenicity, the presence of cysts, with alcoholic liver damage - an increase in its size, diffuse changes in the parenchyma.

Foods rich in magnesium

Treatment of hypomagnesemia

In the vast majority of cases, patients can be treated on an outpatient basis. The need for hospitalization is rare. In parallel with the elimination of hypomagnesemia, the underlying disease is treated and hypokalemia and hypocalcemia are corrected. If hypomagnesemia is caused by taking a drug, then the decision to cancel it should be made by the attending physician strictly individually, depending on the degree of Mg deficiency and the patient's need for this drug.

First of all, a diet is prescribed with the inclusion in the diet of foods rich in magnesium - bananas, nuts, beans. Sometimes this is enough to normalize Mg levels in the blood. If this does not happen, the following drugs are used:

• oral forms. With moderate hypomagnesemia, tablet forms are used - magnesium lactate, orotate, gluconate. It should be borne in mind that diarrhea is a common side effect of these drugs, so they are not recommended for patients with intestinal diseases and malabsorption.
• parenteral forms. In severe hypomagnesemia, magnesium sulfate is administered intravenously at first once, then by infusion, previously diluted in saline NaCl (0.9%). In violation of the excretory function of the kidneys, it is necessary to use smaller doses and reduce the rate of administration to avoid hypermagnesemia. If a patient develops sudden nausea and weakening of tendon reflexes, the administration of the drug should be stopped immediately.

Forecast and prevention

Hypomagnesemia can be considered a relatively benign condition. In most cases, the prognosis for this laboratory syndrome is favorable. Fatal outcomes are extremely rare and are caused by heart rhythm disturbances. However, hypomagnesaemia almost always develops gradually and these complications can be prevented.

Prevention consists in the timely diagnosis and treatment of those diseases against which Mg deficiency may occur. It is necessary to regularly monitor the concentration of magnesium in people suffering from chronic alcoholism, prolonged diarrhea, cardiac patients taking diuretics.