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Magnesium deficiency

When can magnesium deficiency occur?

Even though dietary surveys suggest that many Americans do not consume recommended amounts of magnesium, symptoms of magnesium deficiency are rarely seen in the US. However, there is concern about the prevalence of sub-optimal magnesium stores in the body. For many people, dietary intake may not be high enough to promote an optimal magnesium status, which may be protective against disorders such as cardiovascular disease and immune dysfunction .

The health status of the digestive system and the kidneys significantly influence magnesium status. Magnesium is absorbed in the intestines and then transported through the blood to cells and tissues. Chronic or excessive vomiting and diarrhea may also result in magnesium depletion

Healthy kidneys are able to limit urinary excretion of magnesium to compensate for low dietary intake. However, excessive loss of magnesium in urine can be a side effect of some medications and can also occur in cases of poorly-controlled diabetes and alcohol abuse .

Early signs of magnesium deficiency include loss of appetite, nausea, vomiting, fatigue, and weakness. As magnesium deficiency worsens, numbness, tingling, muscle contractions and cramps, seizures, personality changes, abnormal heart rhythms, and coronary spasms can occur . Severe magnesium deficiency can result in low levels of calcium in the blood (hypocalcemia). Magnesium deficiency is also associated with low levels of potassium in the blood (hypokalemia) .
 

Who may need extra magnesium?

Magnesium supplementation may be indicated when a specific health problem or condition causes an excessive loss of magnesium or limits magnesium absorption .
 Doctors can evaluate magnesium status when above-mentioned medical problems occur, and determine the need for magnesium supplementation.

Table 4 describes some important interactions between certain drugs and magnesium. These interactions may result in higher or lower levels of magnesium, or may influence absorption of the medication.

Table 4: Common and important magnesium/drug interactions
DrugPotential Interaction
  • Loop and thiazide diuretics (e.g. lasix, bumex, edecrin, and hydrochlorthiazide
  • Anti-neoplastic drugs (e.g. cisplatin)
  • Antibiotics (e.g. gentamicin and amphotericin)
  • These drugs may increase the loss of magnesium in urine. Thus, taking these medications for long periods of time may contribute to magnesium depletion 
  • Tetracycline antibiotics
  • Magnesium binds tetracycline in the gut and decreases the absorption of tetracycline .
  • Magnesium-containing antacids and laxatives
  • Many antacids and laxatives contain magnesium. When frequently taken in large doses, these drugs can inadvertently lead to excessive magnesium consumption  and hypermagnesemia, which refers to elevated levels of magnesium in blood.

     
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