Low Magnesium: 9 Important Signs & Symptoms to Know

You are in the hospital, and the doctor says your magnesium level is low. They order an IV containing magnesium sulfate to bring your magnesium level back to a normal level. You wonder if this IV infusion was needed but don’t ask the doctor to explain the importance of magnesium sulfate. Is the hospital trying to run up my bill?

You will get magnesium sulfate only if you need it, say Jay Harold.

Low levels of magnesium, calcium, and potassium are commonly found in hospitalized patients. They are corrected with IV infusions. Jay Harold has previously talked about potassium and calcium imbalances.

MedlinePlus states that Electrolytes are minerals in your body that have an electric charge. They are in your blood, urine and body fluids. Maintaining the right balance of electrolytes helps your body’s blood chemistry, muscle action, and other processes. Sodium, potassium, chloride, calcium, phosphate, and magnesium are all electrolytes.

Magnesium1 is the fourth most abundant mineral in the body. It has been recognized as a cofactor for more than 300 enzymatic reactions, where it is crucial for adenosine triphosphate (ATP stores and transfers energy in cells) metabolism. Magnesium is required for DNA and RNA synthesis, reproduction, and protein synthesis. Moreover, magnesium is essential for the regulation of muscular contraction, blood pressure, insulin metabolism, cardiac excitability, vasomotor tone, nerve transmission and neuromuscular conduction. Imbalances in magnesium status—primarily hypomagnesemia (low) as it is seen more common than hypermagnesemia (high)—might result in unwanted neuromuscular, cardiac or nervous disorders. Based on magnesium’s many functions within the human body, it plays a major role in prevention and treatment of many diseases.

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An adult body contains approximately 25 g magnesium, with 50% to 60% present in the bones and most of the rest in soft tissues. Less than 1% of total magnesium is in blood serum, and these levels are kept under tight control. Normal serum magnesium concentrations range between 0.75 and 0.95 millimoles (mmol)/L. Hypomagnesemia is defined as a serum magnesium level less than 0.75 mmol/L. Magnesium homeostasis (the body seeks to maintain a condition of balance) is largely controlled by the kidney, which typically excretes about 120 mg magnesium into the urine each day. Urinary excretion is reduced when magnesium status is low. Your doctor will monitor magnesium levels from lab results of blood tests.

Common causes2 of low magnesium include:

  • Alcoholism
  • Burns that affect a large area of the body
  • Chronic diarrhea
  • Excessive urination (polyuria), such as in uncontrolled diabetes and during recovery from acute kidney failure
  • High blood calcium level (hypercalcemia)
  • Hyperaldosteronism. Hyperaldosteronism is a disorder in which the adrenal gland releases too much of the hormone aldosterone into the blood. (MedlinePlus)
  • Malabsorption syndromes, such as celiac disease and inflammatory bowel disease. (MedlinePlus)
  • Malnutrition
  • Medicines including amphotericin, cisplatin, cyclosporine, diuretics, proton pump inhibitors, and aminoglycoside antibiotics.

Low levels of Magnesium have been associated with:

  1. Alzheimer’s disease
  2. insulin resistance and type-2 diabetes mellitus
  3. hypertension
  4. cardiovascular disease (e.g., stroke)
  5. migraine headaches
  6. attention deficit hyperactivity disorder (ADHD)

Low magnesium levels can be a medical emergency.

Magnesium: Deficiency signs and symptoms(Table 2) 

1. General: Anxiety, lethargy, weakness, agitation, depression, dysmenorrhea, hyperactivity, headache, irritability, dysacusis, low-stress tolerance, loss of appetite, nausea, sleep disorders, impaired athletic performance.
2. Musculature: Muscle spasm, cramps in the soles of the feet, leg cramps, facial muscles, masticatory muscles, and calves, carpopedal spasm, back aches, neck pain, urinary spasms, magnesium deficiency tetany.
3. Nerves/CNS: Nervousness, increased sensitivity of NMDA receptors to excitatory neurotransmitters, migraine, depression, nystagmus, paraesthesia, poor memory, seizures, tremor, vertigo.
4. Gastrointestinal tract: Constipation.
5. Cardiovascular system: Risk of arrhythmias, supraventricular or ventricular arrhythmias, hypertension, coronary spasm, decreased myocardial pump function, digitalis sensitivity, Torsade de pointes, death from heart disease.
6. Electrolytes: Hypokalaemia, hypocalcemia, retention of sodium.
7. Metabolism: Dyslipoproteinemia (increased blood triglycerides and cholesterol), decreased glucose tolerance, insulin resistance, increased risk of metabolic syndrome, disturbances of bone and vitamin D metabolism, resistance to PTH, low circulating levels of PTH, resistance to vitamin D, low circulating levels of 25(OH)D, recurrence of calcium oxalate calculi.
8. Miscellaneous: Asthma, chronic fatigue syndrome, osteoporosis, hypertension, altered glucose homeostasis.
9. Pregnancy: Pregnancy complications (e.g., miscarriage, premature labor, eclampsia).
Low Magnesium: 9 Important Signs & symptoms to Know

Magnesium Sulfate may prevent pre-term labor for 2 to 7 days.

Magnesium Sulfate delays Preterm Labor

Drugs called tocolytics (pronounced toh-coh-LIT-iks) can be given to many women with symptoms of preterm labor. These drugs can slow or stop contractions of the uterus and may prevent labor for 2 to 7 days. One common treatment for delaying labor is magnesium sulfate4 (pronounced mag-NEEZ-ee-um SUL-fate), given to the pregnant woman intravenously through a needle inserted into an arm vein. Intravenously delivered magnesium sulfate may also reduce the risk of cerebral palsy if the child is born early

Sources of Magnesium2


Magnesium is widely distributed in plant and animal foods and beverages. Green leafy vegetables, such as spinach, legumes, nuts, seeds, and whole grains, are good sources. In general, foods containing dietary fiber provide magnesium. Magnesium is also added to some breakfast cereals and other fortified foods. Some types of food processing, such as refining grains in ways that remove the nutrient-rich germ and bran, lower magnesium content substantially. Selected food sources of magnesium are listed in Table 2.

Tap, mineral, and bottled waters can also be sources of magnesium, but the amount of magnesium in water varies by source and brand (ranging from 1 mg/L to more than 120 mg/L).

Approximately 30% to 40% of the dietary magnesium consumed is typically absorbed by the body.

Dietary supplements

Magnesium supplements are available in a variety of forms, including magnesium oxide, citrate, and chloride. The Supplement Facts panel on a dietary supplement label declares the amount of elemental magnesium in the product, not the weight of the entire magnesium-containing compound.

Low Magnesium: 9 Important Signs & symptoms to Know

Magnesium is a primary ingredient in some laxatives.

Absorption of magnesium from different kinds of magnesium supplements varies. Forms of magnesium that dissolve well in liquid are more completely absorbed in the gut than less soluble forms. Small studies have found that magnesium in the aspartate, citrate, lactate, and chloride forms is absorbed more completely and is more bioavailable than magnesium oxide and magnesium sulfate. One study found that very high doses of zinc from supplements (142 mg/day) can interfere with magnesium absorption and disrupt the magnesium balance in the body.


Magnesium is a primary ingredient in some laxatives. Phillips’ Milk of Magnesia®, for example, provides 500 mg elemental magnesium (as magnesium hydroxide) per tablespoon; the directions advise taking up to 4 tablespoons/day for adolescents and adults. (Although such a dose of magnesium is well above the safe upper level, some of the magnesium is not absorbed because of the medication’s laxative effect.) Magnesium is also included in some remedies for heartburn and upset stomach due to acid indigestion. Extra-strength Rolaids®, for example, provides 55 mg elemental magnesium (as magnesium hydroxide) per tablet, although Tums® is magnesium free.

It’s easy to feel overwhelmed by medical talk, but you need to have some knowledge of what’s hanging on that pole beside the hospital bed. Use MedlinePlus as a free reference.

Enjoyed this post? Share it and read more here.  Jay Harold has put together a Resource page that you may find useful when trying to improve your health and wealth. Please take this advice of  Muhammad Ali and give back to others. “Service to others is the rent you pay for your room here on earth.” ~ Muhammad Ali


  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4586582/
  2. https://medlineplus.gov/ency/article/000315.htm
  3. https://www.nichd.nih.gov/health/topics/preterm/conditioninfo/Pages/reduce.aspx
  4. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/

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