What is Hypomagnesemia?

The normal concentration of serum magnesium is 0.75 to 1.25 mmol / L. Its regulation is mainly done by the kidneys. The kidneys excrete magnesium and potassium similarly, that is, despite the decrease in serum magnesium concentration, the renal magnesium excretion does not stop. In many diseases, abnormal magnesium metabolism can often occur. Serum magnesium <0.75mmol / L is called hypomagnesemia.

Basic Information

English name

Hypomagnesemia

Visiting department

Internal medicine

Common causes

Excessive digestive tract and kidney loss, insufficient supplementation, and primary hyperparathyroidism can cause symptomatic magnesium deficiency

Common symptoms

Early anorexia, nausea, vomiting, weakness and indifference, memory loss, nervousness, irritability, unconsciousness, and epileptic seizures in severe cases

Causes of hypomagnesemia

Common reasons are:

1. Excessive loss of digestive tract

Because magnesium is absorbed in the small intestine and part of the colon, hypomagnesemia can be caused by severe diarrhea, fatty diarrhea, malabsorption, intestinal fistula, and major small bowel resection.

2. Excessive kidney loss

Such as chronic pyelonephritis, renal tubular acidosis, polyuria during acute renal failure, or long-term application of diuretics, thiazines, and osmotic diuretics, which causes renal loss of magnesium and hypomagnesemia.

3. Insufficient supplement

In malnutrition, magnesium deficiency in nutritional support fluids for some diseases, or even long-term application of magnesium-free solutions.

4. Hyperthyroidism patients are often accompanied by hypomagnesemia and negative nitrogen balance

Primary hyperparathyroidism can cause symptomatic magnesium deficiency.

Clinical manifestations of hypomagnesemia

Early manifestations of magnesium deficiency often include anorexia, nausea, vomiting, weakness and apathy. Aggravated magnesium deficiency may have memory loss, nervousness, irritability, unconsciousness, irritability, and hand, foot, and throbbing movements. In severe magnesium deficiency, seizures may occur. In addition, arrhythmia can be caused during hypomagnesemia. Magnesium is a substance necessary for activating Na + -K + -ATPase. Deficiency of magnesium can cause myocardial cells to lose potassium. The electrocardiogram can show that the PR and QT intervals are prolonged, the QRS wave is widened, the ST segment is decreased, and the T wave is widened. Inverted, occasionally U-waves, confused with hypokalemia, or related to changes in serum potassium and calcium.

Hypomagnesemia test

1. Determination of serum magnesium.

2. Magnesium load test.

Diagnosis of hypomagnesemia

The easiest method is to measure serum magnesium. However, the diagnosis of magnesium deficiency is sometimes difficult, and sometimes serum magnesium is normal. Hypomagnesemia cannot be denied because it is affected by changes in pH, protein, and other factors.

For some patients who have hypoglycemia due to predisposing factors, their symptoms are difficult to distinguish from hypokalemia. If the situation does not improve after potassium supplementation, hypomagnesemia should be considered. In addition, in patients with convulsions and suspected to be associated with calcium deficiency, magnesium deficiency should also be suspected when convulsions cannot be relieved after calcium injection.

Hypomagnesemia Treatment

Prevention and treatment of primary diseases

Prevent or eliminate the cause of hypomagnesemia.

2. Magnesium supplement

Severe hypomagnesemia and symptoms, especially when various types of arrhythmia must be supplemented with magnesium in a timely manner. For severe arrhythmias caused by magnesium deficiency, other treatments are often ineffective. Only slow intravenous injection or infusion of magnesium salts (usually magnesium sulfate) will work. Intravenous magnesium supplements should be used with caution, especially if the patient's renal function is impaired. In the process of magnesium supplementation, the serum magnesium concentration must be measured frequently, and it must be prevented from turning into hypermagnesemia due to excessive magnesium supplementation. Intravenous magnesium supplementation in children should also pay special attention to prevent the occurrence of hypotension, because magnesium can expand blood vessels such as peripheral arteries. For mild hypomagnesemia, magnesium can be supplemented by intramuscular injection. The dose of magnesium supplement depends on the degree of magnesium deficiency and the severity of the symptoms.

3. Correct water and electrolyte metabolism disorders

Including hydration, especially potassium and calcium, because hypomagnesemia is often accompanied by dehydration, hypokalemia, and hypocalcemia.