What it is: A magnesium blood test measures the level of magnesium, an electrolyte important for nerve, muscle, and heart function, in the blood.
Why it's ordered: Ordered when symptoms like muscle cramps, weakness, irregular heartbeat, or unexplained potassium abnormalities raise concern, or to monitor kidney disease or chronic alcohol use.
What it detects: Magnesium supports hundreds of enzyme reactions and works closely with potassium; abnormal potassium that won't correct on its own often points to an underlying magnesium problem.
Collection & prep: A standard blood draw from a vein in the arm. No special preparation is typically required.
Results:
Low – can cause muscle cramps, weakness, or heart rhythm problems; linked to poor intake, GI losses, or certain medications
High – less common; usually linked to kidney disease or excess magnesium intake (e.g., certain antacids or laxatives)
Normal – magnesium levels appear balanced
Possible complications of low magnesium: Significant magnesium deficiency can cause muscle spasms, seizures, or dangerous heart rhythms, and can make it difficult to correct low potassium until magnesium is also replaced.
Statements made in the Clinical Manual have not been evaluated by the FDA. The products mentioned are not intended to diagnose, treat, cure or prevent any disease.
