Magnesium (Mg)

Your body needs magnesium to help your muscles, nerves, and heart work properly. Magnesium also helps control blood pressure and blood glucose, also called blood sugar. It's important for building strong bones, and it supports your immune system.

Magnesium is a type of electrolyte. Electrolytes are electrically charged minerals. They help control the amount of fluid and the balance of acids and bases (pH balance) in your body.

Most of your body's magnesium is stored in your bones, organs, and other body tissue. Only a small amount is found in your blood. Your body tightly controls the amount of magnesium in your blood.

If the results of your magnesium blood test are abnormal, your provider will use your medical history and the results of other tests to diagnose the cause. Many different conditions can affect magnesium levels, so ask your provider to explain what your test results mean.

Lower than normal magnesium can be linked to long-standing kidney inflammation, sudden inflammation of the pancreas, and liver damage from heavy alcohol use. Other health conditions linked to low magnesium include underactive parathyroid glands and pregnancy, which increases the need for magnesium. When magnesium runs low, it can also cause symptoms like irritability, muscle and nerve problems, and effects on the heart and kidneys. Symptoms of low magnesium often don't appear until the level falls to about 1.2 mg/dL or below.

Higher than normal magnesium levels can occur with sudden or long-term kidney failure and with Addison's disease (an adrenal gland disorder), and may need follow-up testing to determine the cause. Very high magnesium can depress the central nervous system, leading to muscle weakness and, in severe cases, breathing or heart problems. Levels around 9.0 mg/dL and higher can be life-threatening.