Magnesium plays an important role in the function of nerve and muscle cells. According to "Fluids and Electrolytes DeMystified," the normal range of magnesium in the bloodstream is 1.3 to 2.5 mEq/L. An excess or decreased level of magnesium icould lead to abnormal heart rhythms or cardiac arrest.
History
Magnesium is an important electrolyte that helps with nerve and muscle function. Excessive amounts of magnesium or decreased levels can severely disrupt body function. As magnesium levels increase, reflexes are lost and progress from loss of deep tendon reflexes to sleepiness, then ultimately to respiratory and cardiac arrest. If levels are too low, cardiac and nerve muscles are irritated and have abnormal excitability.
Regulation of Magnesium
Magnesium is regulated by the kidney functioning and their ability to excrete excess magnesium through urine output. Any patient who has decreased kidney function is at risk for developing hypermagnesemia, which is elevated magnesium. Patients who may be on medications to increase urine output and do not replace magnesium by diet or supplements, could develop hypomagnesemia, which is low magnesium.
Magnesium's Effect On Heart
According to "Fluids and Electrolytes DeMystified," high levels of magnesium will cause the patient's heartbeat to slow down, which could lead to cardiac arrest. Magnesium, in high levels, has a sedative effect. Hypomagnesemia has the opposite effect and can stimulate heart muscle causing irritability. The heightened electrical stimulation and muscle excitability precipitate abnormal heart rhythms that require treatment.
Identification
Magnesium levels can be monitored through blood tests. In addition to blood levels, there are patient populations who are at higher risk of developing an imbalance. Patients who have a history of alcohol abuse are at risk for having low levels of magnesium because of liver dysfunction, vomiting and diarrhea. Hypermagnesemia is common in elderly patients with decreased kidney function or those taking over-the-counter magnesium containing antacids or cathartics. In these patient populations, a high suspicion of magnesium imbalance should be considered and watched for.
Symptoms and Treatments
Symptoms of low magnesium may include tremors, seizures and muscle twitching in addition to the abnormal heart rhythms. High magnesium will cause low blood pressure, drowsiness and loss of reflexes in addition to respiratory and cardiac arrest. Treatment for low magnesium may include stopping medications that may be increasing urine output, dietary modifications and magnesium supplements. High levels of magnesium may include hydrating the patient with intravenous fluids, giving diuretic medications and in some cases calcium, which counteracts the effect of magnesium may be necessary.
References
- "Fluids and Electrolytes DeMystified"; McGraw Hill; 2008
- "American Journal of Health System Pharamists": Magnesium in carrdiovascular and other disorders; Gums; Aug 2004
