What Is Magnesium in a Blood Test?

Magnesium is essential for over 300 enzymatic reactions, including muscle and nerve function, blood glucose control, and blood pressure regulation.

Normal Range

• 1.7–2.2 mg/dL
• Hypomagnesemia: below 1.7 mg/dL
• Hypermagnesemia: above 2.2 mg/dL (rare, usually kidney disease)

Low Magnesium Causes

• GI losses — diarrhea, vomiting, malabsorption
• Renal losses — diuretics, alcohol, uncontrolled diabetes
• Inadequate intake — poor diet, alcoholism
• Medications — PPIs (omeprazole), diuretics, aminoglycosides

Symptoms of Low Magnesium

• Muscle cramps and tremors
• Cardiac arrhythmias
• Weakness
• Numbness/tingling
• Seizures (severe)
• Personality changes

Why Serum Magnesium Has Limitations

• Only 1% of body magnesium is in the blood
• 99% is stored in bones and inside cells
• Serum level may be normal even with total body depletion
• RBC magnesium or 24-hour urine magnesium may be more accurate