hypomagnesemia



OVERVIEW

Definition.

Hypomagnesemia is a pathologic condition in which the serum magnesium ion concentration is <0.75 mmol/L.

The normal concentration of serum magnesium ion is 0.75～1.25mmol/L. When magnesium is deficient, the stress of nerves, muscles, and cardiac muscle is enhanced, and the acute symptoms of hypomagnesemia may include tremor, twitching of hands and feet, and panic attacks, etc., while the symptoms of chronic hypomagnesemia may not be obvious [1-2].

Treatment of primary disease is the main focus to remove the cause of low magnesium, most patients have a good prognosis after timely treatment.

Morbidity

Hypomagnesemia occurs in about 12% of hospitalized patients in clinical practice [3]. The incidence is higher in intensive care unit patients, up to 60%-65% [4].

Etiology.

Causes of hypomagnesemia include inadequate magnesium intake, excessive loss, and intracellular transfer of serum magnesium.

Pathogenic causes

Inadequate magnesium intake

It is seen in old and frail people who eat little, or patients who have been fasting for a long time, anorexia or long-term intravenous nutrition without magnesium supplementation.

Excessive magnesium loss

Hypomagnesemia is often secondary to gastrointestinal, endocrine, renal or other metabolic diseases, and magnesium is mainly lost through the gastrointestinal tract and kidneys.

Under normal circumstances, magnesium is absorbed in the small intestine and part of the colon. When small intestinal pathology occurs, such as surgical resection of the small intestine, severe diarrhea, or prolonged gastrointestinal decompression and drainage, magnesium absorption in the digestive tract decreases and excretion increases, causing hypomagnesemia.

Drugs or endocrine and renal diseases can cause renal loss of magnesium.

Drugs: furosemide can inhibit the reabsorption of magnesium in renal tubules, osmotic diuretics mannitol, urea or hypertonic glucose can also increase magnesium excretion with urine, and other drugs such as aminoglycosides, cisplatin, amphotericin B, cyclosporine can also cause hypomagnesemia.

Diabetic ketoacidosis: on the one hand, acidosis can obviously hinder the reabsorption of magnesium in renal tubules, on the other hand, high blood sugar makes magnesium increase with urinary excretion.

Hypoparathyroidism: due to the decreased secretion of parathyroid hormone, the tubular reabsorption of magnesium and phosphate is reduced, thus the renal excretion of magnesium is increased.

Hyperthyroidism: thyroid hormones inhibit tubular reabsorption of magnesium.

Renal disease: acute organic renal failure with polyuric stage, chronic pyelonephritis, etc., can cause osmotic diuresis and impaired renal tubular function, resulting in increased renal excretion of magnesium.

Hypercalcemia: calcium and magnesium are reabsorbed in the renal tubules with a competitive effect on each other, so hypercalcemia due to any cause can reduce the reabsorption of magnesium in the renal tubules.

Extracellular magnesium is transferred to intracellular

When insulin is used to treat diabetic ketoacidosis, excessive magnesium is transferred to intracellular and extracellular fluid magnesium is reduced due to the promotion of glycogen synthesis, causing a decrease in serum magnesium [5-6].

Hereditary renal defects

Genetic disorders such as Gitelman syndrome, familial hypomagnesemia with hypercalciuria, and Kearns-Sells syndrome can also cause hypomagnesemia.

Symptoms

Acute clinical manifestations of hypomagnesemia include neuromuscular hyperexcitability and cardiac arrhythmias, but hypomagnesemia can also have a chronic course with no specific symptoms. Chronic magnesium depletion may lead to hypertension, atherosclerotic vascular disease, and metabolic bone disease.

Major Symptoms

Neuromuscular symptoms

Neuromuscular hyperexcitability is manifested by tremor, hand and foot twitching, and convulsions.

It may be accompanied by symptoms such as emotional apathy, anxiety, agitation, etc. In severe cases, it may cause epileptic seizures, mental confusion and coma.

Cardiovascular symptoms

In patients with acute ischemic events, congestive heart failure, etc., magnesium deficiency can easily induce arrhythmia.

In more severe cases of magnesium deficiency, there is prolongation of the PR interval, progressive widening of the QRS complex and flattening of the T wave, frequent atrial and ventricular pre-systole, and persistent atrial fibrillation, with symptoms such as missed beats and panic attacks.

In the general population, low serum magnesium levels may be a risk factor for heart failure, coronary artery disease, and hypertension [6-8].

Metabolic abnormalities

Hypomagnesemia can lead to abnormalities in calcium metabolism, including hypocalcemia, hypoparathyroidism, parathyroid hormone resistance, and decreased synthesis of osteotriol, which may further lead to osteoporosis, low back pain, and fractures [9].

Medical treatment

Department of Medicine

Endocrinology

If labs indicate decreased blood magnesium without specific symptoms, endocrinology may be consulted.

Emergency Medicine

If there are symptoms such as tremor, convulsions of hands and feet, blurred consciousness, coma, etc., it is recommended to consult the Department of Emergency Medicine.

Cardiovascular Medicine

If you experience symptoms of arrhythmia such as chest tightness and panic attacks, we recommend consulting the Department of Cardiovascular Medicine.

Preparation

Preparation for consultation: registration, preparation of documents, common problems

Tips for the doctor

Wear clothes that are easy to put on and take off for the doctor’s examination.

It is recommended to keep a record of the date of onset of symptoms and the duration of the attack for the doctor’s reference.

Preparation Checklist

Pay particular attention to the time of onset of symptoms, special manifestations, etc.

Are there any symptoms such as emotional apathy, anxiety, agitation, tremor, twitching of hands and feet?

Are there any symptoms such as self-consciousness of chest tightness, panic attacks, etc.?

When did the above symptoms start? How long have they lasted?

Is there any history of hypokalemia?

Is there any long-term fasting, anorexia, or long-term intravenous nutrition?

Is there any surgical resection of small intestine, severe diarrhea or long-term gastrointestinal decompression and drainage?

Are there any endocrine diseases such as hyperthyroidism, parathyroidism, diabetic ketoacidosis, etc.?

Are there conditions such as chronic pyelonephritis or acute organic renal failure?

Are there any hereditary diseases such as Gitelman syndrome, familial hypomagnesemia with hypercalciuria, Kearns-Searle syndrome, etc.?

Any medications such as diuretics, cisplatin, amphotericin B, cyclosporine, etc.?

Test results in the last 1 week that can be brought to the doctor’s office

Laboratory tests: blood test, liver and kidney function, blood electrolytes, urine electrolytes, thyroid hormone, etc.

Auxiliary tests: electrocardiogram, head CT, etc.

Diagnosis

Symptoms and signs of hypomagnesemia are very atypical and easily hidden by its primary diseases, which need to be analyzed comprehensively with medical history, symptoms, laboratory tests, etc.

Diagnosis

Medical history

Patients with this disease may have a history of the following

A history of prolonged fasting, anorexia, or prolonged intravenous nutrition.

There is surgical resection of the small intestine, severe diarrhea, or prolonged gastrointestinal decompression and drainage.

Have endocrine disorders such as hyperthyroidism, parathyroidism, or diabetic ketoacidosis.

There are diseases such as chronic pyelonephritis and acute organic renal failure.

There are genetic diseases such as Gitelman syndrome, familial hypomagnesemia with hypercalciuria, and Kearns-Searle syndrome.

There are taking drugs such as diuretics, cisplatin, amphotericin B, cyclosporine.

Clinical manifestations

Hypomagnesemia may have symptoms such as emotional apathy, anxiety, agitation, tremor, hand and foot twitching, or symptoms of cardiac arrhythmia such as chest tightness and panic.

Hypomagnesemia may also have no specific symptoms.

Laboratory Tests

A serum magnesium concentration of less than 0.75 mmol/L and a 24-hour urinary excretion of less than 36 mg of magnesium are diagnostic of magnesium deficiency.

Magnesium is administered intravenously and the percentage of magnesium retained is calculated; a magnesium retention index >50% is considered magnesium deficiency [6].

Differential diagnosis

Hypokalemia, hypocalcemia and hypomagnesemia have similar symptoms and need to be differentiated as follows.

Hypokalemia

Hypokalemia is characterized by weakness, arrhythmia, abdominal distension, muscle weakness, etc. The serum potassium ion concentration is <3.5 mmol/L, which can be identified by combining with blood biochemistry or electrolyte test.

It should be noted that hypomagnesemia is often accompanied by hypokalemia, and it is difficult to restore potassium to normal if hypokalemia is not corrected, so the treatment should pay attention to the simultaneous treatment of both.

Hypocalcemia

Hypocalcemia refers to blood calcium ≤2.13mmol/L with normal serum protein concentration, which is mainly manifested by different degrees of muscle spasms, tetany, dry skin, etc. It is often caused by vitamin D metabolism disorder, hypoparathyroidism, chronic renal failure and so on.

Treatment

Aim of treatment: to relieve symptoms and correct hypomagnesemia.

Treatment principle: acute symptoms caused by magnesium deficiency require urgent intravenous magnesium supplementation, and effective treatment should be directed at the cause of hypomagnesemia.

General treatment

Active treatment of primary disease: such as hyperthyroidism, hypoparathyroidism, diabetic ketoacidosis, malnutrition, renal failure.

Nutritional support: eat more magnesium-rich foods, such as moss cabbage, sea cucumber, pine nuts, watermelon seeds, pumpkin seeds, etc [6].

Adjustment of drugs: if long-term application of diuretics, cisplatin, amphotericin B, etc., the drugs can be adjusted according to the doctor’s requirements.

Drug treatment

Intravenous or intramuscular magnesium sulfate should be used when urgent correction of hypomagnesemia is required, such as in the case of convulsions, myocardial ischemia, and tip-twist ventricular tachycardia. Treatment often requires 5 consecutive days to stabilize blood magnesium in the normal range, and oral magnesium therapy can be switched when blood magnesium returns to normal levels.

Mild to moderate hypomagnesemia can be treated with oral replacement medications such as magnesium oxide, magnesium sulfate, magnesium lactate, magnesium hydroxide, and magnesium chloride are available. Often start with a small dose, and then gradually increase, in order not to cause diarrhea is appropriate, daily divided service can make the diarrhea reduce.

If the patient’s renal function is not good, easy to occur hypermagnesemia. The therapeutic dose should be appropriately reduced. Blood magnesium needs to be measured during magnesium supplementation to guide the dosage of magnesium.

Patients with concomitant hypocalcemia and hypokalemia usually need to be supplemented with both calcium and potassium to facilitate improvement of hypomagnesemia [6,10-12].

Questions you may be concerned about

How to supplement magnesium in hypomagnesemia

Patients with hypomagnesemia can be supplemented with magnesium ions through oral or intravenous routes, such as potassium magnesium menthylate and magnesium sulfate injection.

Hypomagnesemia is a medical condition in which the patient’s serum magnesium concentration is less than 0.75 mmol/L. It is usually supplemented by oral magnesium, such as magnesium oxide, magnesium hydroxide, magnesium acetate, etc. Severe patients can be supplemented intravenously, such as potassium magnesium menthionate, magnesium sulfate injection and so on. While supplementing magnesium intravenously, blood magnesium concentration should be monitored to prevent hypermagnesemia.

Magnesium supplementation should be accompanied by monitoring the concentration of electrolytes such as calcium and potassium to prevent electrolyte disorders. Patients with hypomagnesemia should also be treated for the cause of the disease. The main causes of hypomagnesemia include excessive loss from the digestive tract, excessive loss from the kidneys, inadequate supplementation, and primary hyperparathyroidism. Treatment includes prevention and treatment of primary diseases, magnesium supplementation, and correction of disorders of water-electrolyte metabolism.

Since some adverse reactions may occur during magnesium supplementation, it is recommended that magnesium supplementation therapy be carried out under the supervision of a physician.

Prognosis

The prognosis of hypomagnesemia depends on the cause of the disease and the severity of the disease, and the prognosis of each patient may be different, which needs to be judged according to the specific situation.

Cure

When magnesium deficiency causes acute symptoms, aggressive intravenous magnesium supplementation usually results in improvement.

Hypomagnesemia caused by endocrine diseases (e.g., hyperthyroidism, hypoparathyroidism) may improve after elimination of the primary disease.

Other diseases such as small bowel resection, chronic pyelonephritis, renal failure, etc., the disease is difficult to cure, mainly through long-term oral magnesium symptomatic treatment.

In general, the cure rate of mild hypomagnesemia is high, and the cure rate of severe hypomagnesemia is low, which may cause serious complications.

Hazards

Acute hypomagnesemia can cause conditions such as convulsions and tip-twist ventricular tachycardia, which may be life-threatening.

Long-term chronic magnesium deficiency may lead to hypertension, atherosclerotic vascular disease, heart failure, and metabolic bone disease.

Daily

Patients with hypomagnesemia can basically return to normal life after treatment. A healthy lifestyle is needed on a daily basis, and the general population is advised to be proactive in the prevention and treatment of primary illnesses.

Daily management

Dietary management

Maintain a normal diet without picking and choosing food.

Eat more magnesium-rich foods, such as beans, dried fruits, grains and meat.

Life management

In case of twitching of hands and feet, etc., bed rest is recommended to prevent falls and injuries.

Quit smoking and limit alcohol.

Increase sunlight, regular rest and avoid overwork.

Avoid bad emotions such as tension, anxiety, anger and depression.

Prevention

Ensure a balanced diet with a variety of food types and moderate intake of dairy products.

When long-term use of diuretics, mannitol, amphotericin B and other drugs, should pay attention to the monitoring of blood and urine electrolytes, and follow the doctor’s instructions to adjust the use of drugs or magnesium supplements.

Active treatment of related diseases, such as chronic diarrhea, hyperthyroidism, renal failure.