Magnesium
A mineral involved in hundreds of enzyme reactions, including energy production, muscle and nerve function.
| Typical reference range | 1.5–2.5 mg/dL |
| Commonly cited optimal range | 2–2.4 mg/dL |
Ranges vary by laboratory, method, age and sex: always use the range printed on your own report. Why labs differ.
What it measures
Magnesium is a cofactor for over 300 enzymes, including those that make ATP, DNA and proteins. Only about 1% of the body's magnesium is in blood; most is in bone and inside cells.
Why it matters
Low magnesium can cause muscle cramps, arrhythmias and low potassium and calcium that do not correct until magnesium is replaced. Serum levels are a late and insensitive marker of whole-body stores.
What a high result can mean
High magnesium is uncommon and usually seen with kidney failure or heavy use of magnesium-containing laxatives or antacids.
What a low result can mean
Low magnesium can result from low dietary intake, alcohol use, diarrhea or malabsorption, diuretics, proton pump inhibitors, poorly controlled diabetes and some chemotherapy drugs.
What affects the result
Serum magnesium can be normal despite low tissue stores; RBC magnesium is sometimes used as an alternative indicator. Leafy greens, nuts, seeds, legumes and whole grains are good sources. Hemolysis falsely raises the result.
Units and conversion
Usually reported in mg/dL.
- From mmol/L: multiply by 2.431 to get mg/dL
- From mEq/L: multiply by 1.215 to get mg/dL
Also called on lab reports
Mg, Magnesium, Serum, Serum Magnesium
Related tests: Electrolytes & Minerals
This page is educational and does not replace advice from a healthcare professional.