Magnesium is a mineral found in the blood and bones. Magnesium plays an important role in the control of the neuromuscular junction, which is where the nervous system is able to connect to the muscular system. Low magnesium can be caused by abnormally high calcium levels (which will cause the body to eliminate magnesium) or by poor nutrition. It can also be caused by alcoholism or severe diarrhea. Hypomagnesemia is a serious condition that can be life-threatening if not immediately treated.
Muscular Problems
Some of the earliest symptoms of low magnesium levels are manifested in problems with the muscular system. Specifically, patients with hypomagnesemia commonly experience muscle cramps and spontaneous muscle spasming (also known as muscular fibrillation) that stems from the muscles being unusually excitable. Patients also will have increased deep tendon reflexes (such as patellar reflex in which the tendon below the kneecap is lightly tapped with a hammer, causing the leg to kick). Patients may also have problems swallowing as a result of spasm of the esophageal muscles.
Nervous System Excitability
Hypomagnesemia can also have effects on the nervous system. Patients with low levels of magnesium can become abnormally combative and are easily irritated. They may also experience disorientation, which can proceed to psychosis. If magnesium levels get severely low, they can cause vertigo, nyastagmus (uncontrollable eye movements) and seizures.
Cardiac Problems
Low levels of magnesium can also cause problems with the heart. Typically this causes arrythmias, which can lead to a sensation that the patient's heart is skipping a beat. Some patients also feel like their heart is racing or pounding. If untreated, these arrythmias can disrupt the heart's function, leading to a heart attack.
Side Effects in Babies
Because it can be difficult to observe some of the muscular excitability in newly born babies, doctors typically look for some specific neonatal side effects of hypomagenesemia. These include long pauses in breathing (apnea) as well as weakness (most commonly observed by difficulty grasping a finger). Neonates may also seem unusually agitated or experience seizures.
Other Side Effects
Doctors may also test for hypomagnesemia by looking for Trousseau's and Chvostek's signs, which are side effects caused by muscular excitability. Trouseau's sign is elicited by inflating a blood pressure cuff above the patient's systolic blood pressure level and leaving it at that pressure for three minutes. Patients with hypomagnesemia will develop uncontrollable muscle contractions, including flexion of the thumb and extension of the fingers. Chvostek's sign involves tapping the patient at a specific spot on their face (just in front of the ear) and seeing if the muscles on that side of their face twitch.
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