From the Guidelines
Hypomagnesemia is most commonly caused by decreased absorption or increased loss of magnesium from either the kidneys or intestines, as well as alterations in thyroid hormone function, certain medications, and malnourishment. The primary causes of hypomagnesemia include inadequate dietary intake of magnesium, increased gastrointestinal losses through diarrhea or vomiting, alcoholism, certain medications (especially proton pump inhibitors like omeprazole, diuretics like furosemide, and some antibiotics like aminoglycosides), malabsorption syndromes, chronic kidney disease, diabetic ketoacidosis, and endocrine disorders like hyperparathyroidism or hyperthyroidism 1.
Common Causes of Hypomagnesemia
- Inadequate dietary intake of magnesium
- Increased gastrointestinal losses through diarrhea or vomiting
- Alcoholism
- Certain medications (especially proton pump inhibitors, diuretics, and some antibiotics)
- Malabsorption syndromes
- Chronic kidney disease
- Diabetic ketoacidosis
- Endocrine disorders like hyperparathyroidism or hyperthyroidism
Prolonged use of magnesium-free intravenous fluids can also lead to hypomagnesemia, particularly in critically ill patients 1. Certain genetic disorders affecting magnesium transport in the kidneys, such as Gitelman syndrome, can cause chronic hypomagnesemia. Treatment depends on the underlying cause but often includes oral magnesium supplements like magnesium oxide (400-800 mg daily) or magnesium citrate for mild cases, while severe symptomatic cases may require intravenous magnesium sulfate 1. Hypomagnesemia is clinically significant because magnesium is essential for numerous enzymatic reactions, neuromuscular function, and cardiac electrical stability, with deficiency potentially causing symptoms ranging from muscle cramps and weakness to cardiac arrhythmias and seizures.
From the FDA Drug Label
As plasma magnesium rises above 4 mEq/L, the deep tendon reflexes are first decreased and then disappear as the plasma level approaches 10 mEq/L. At this level respiratory paralysis may occur. Heart block also may occur at this or lower plasma levels of magnesium. Serum magnesium concentrations in excess of 12 mEq/L may be fatal. Early symptoms of hypomagnesemia (less than 1. 5 mEq/L) may develop as early as three to four days or within weeks. Predominant deficiency effects are neurological, e.g., muscle irritability, clonic twitching and tremors. Hypocalcemia and hypokalemia often follow low serum levels of magnesium.
The causes of hypomagnesemia are not directly stated in the provided drug labels. However, the labels do mention that hypomagnesemia can arise during the course of total parenteral nutrition (TPN) therapy 2. Additionally, the labels describe the effects of low serum magnesium levels, including neurological symptoms such as muscle irritability, clonic twitching, and tremors, as well as the potential for hypocalcemia and hypokalemia to follow low serum levels of magnesium 2.
From the Research
Causes of Hypomagnesemia
- Inadequate magnesium intake 3, 4, 5
- Increased gastrointestinal losses, such as:
- Increased renal losses, such as:
- Redistribution from extracellular to intracellular space 3, 4
- Cellular redistribution of Mg, such as in alcoholics and diabetic patients 4
Clinical Presentations of Hypomagnesemia
- Neuromuscular irritability 4
- Cardiac arrhythmias, including ventricular arrhythmia 3, 4
- Increased sensitivity to digoxin 4
- Refractory hypokalemia and hypocalcemia 4