Magnesium is a blood test that measures magnesium levels in the blood. Normal range: Serum magnesium is typically 0.70-1.10 mmol/L. A limitation worth knowing: blood magnesium can look normal while total body stores are depleted, because most magnesium is held inside cells and bone rather than in the bloodstream.. It is commonly used to important for energy production, muscle function, and nervous system regulation..
What is Magnesium?
A mineral essential for over 300 biochemical reactions in the body.
Why is it measured?
Important for energy production, muscle function, and nervous system regulation.
Normal Reference Range
Serum magnesium is typically 0.70-1.10 mmol/L. A limitation worth knowing: blood magnesium can look normal while total body stores are depleted, because most magnesium is held inside cells and bone rather than in the bloodstream.
Note: Reference ranges may vary between laboratories. Always consult your healthcare provider for interpretation.
What Causes High MAGNESIUM?
High magnesium is uncommon and is usually caused by reduced kidney clearance (chronic kidney disease or kidney failure) combined with magnesium-containing antacids or laxatives. It can also occur with adrenal insufficiency (Addison's disease). Marked elevation depresses reflexes, lowers blood pressure and, when severe, affects heart rhythm and breathing.
What Causes Low MAGNESIUM?
Low magnesium is far more common and frequently overlooked. Causes include gastrointestinal losses (chronic diarrhoea, vomiting, malabsorption), excess alcohol, poor intake, and medications — particularly proton-pump inhibitors (long-term PPIs), diuretics and some chemotherapy. Low magnesium causes muscle cramps, tremor and arrhythmias, and characteristically makes low potassium and low calcium resistant to correction until the magnesium is replaced.
How Often Should MAGNESIUM Be Tested?
Magnesium is checked when someone has unexplained low potassium or calcium, cardiac arrhythmias, muscle cramps or tremor, heavy alcohol use, or is on long-term PPIs or diuretics. It is monitored in chronic kidney disease and during magnesium replacement. It is not part of every routine panel.
Related Blood Markers
Magnesium is closely linked to potassium and calcium — all three are often abnormal together, and magnesium must be corrected first. Kidney function (creatinine and eGFR) explains high levels.
Key Facts
- •Category: Nutritional Status
- •Unit of Measurement: mmol/L
- •Test Code: MAGNESIUM
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