Magnesium is a positively charged electrolyte found within the cells. Magnesium is found primarily within the bones, soft tissues and muscle cells. It plays a major role in the excitability of nerves and muscles, including the heart's conduction system. The kidneys assist in conserving magnesium when levels are low and excrete magnesium when levels are high.
According to "Fluids and Electrolytes DeMystified," the regulation and balance of magnesium, potassium and calcium are interrelated. Symptoms of magnesium imbalance are often mixed with symptoms of calcium or potassium imbalances. Potassium and calcium also play a role in the excitability of nerves and muscle cells. With magnesium, as levels increase, neuromuscular function is depressed, whereas a deficient level of magnesium results in increased excitability. Magnesium reserves are stored in bones and some in the kidneys.
Low magnesium, also called hypomagnesemia, occurs when the concentration in the bloodstream falls below 1.5 mEq/L, according to "Current Diagnosis and Treatment Emergency Medicine." Hypomagnesemia is common and occurs in approximately 12 percent of hospitalized patients. Symptoms are rare until levels fall below 1 mEq/L. Symptoms are often nonspecific and may mimic those of low calcium and low potassium.
Low levels of magnesium are primarily caused from decreased absorption in the gastrointestinal tract or excessive excretion of magnesium in the urine. Malnutrition often associated with alcohol abuse can cause decreased absorption. Increased demands during pregnancy can contribute to decreased absorption. Patients who take medications called diuretics to help increase urine excretion are at risk for hypomagnesemia.
Hypomagnesemia will cause increased irritability of nerves and muscles. Patients may have muscle tremors, hyperactive reflexes and involuntary contraction of the muscles. Other symptoms may include twitching of the eye, loss of appetite, restlessness and confusion. In severe cases of hypomagnesemia, patients may hallucinate and have seizures and irregular heart rhythms.
The primary treatment for hypomagnesemia is oral supplements and increased dietary intake of foods containing magnesium. Foods rich in magnesium include dark-green vegetables, nuts and chocolate. Magnesium supplements can also include magnesium-containing antacids. If magnesium levels are extremely low, intravenous or intramuscular injections may be required. Patients receiving intravenous supplements need to be monitored closely because rapid administration can result in cardiac or respiratory arrest.
- "Fluids and Electrolytes DeMystified"; McGraw Hill; 2008
- "Current Diagnosis and Treatment Emergency Medicine"; McGraw Hill; 2008