Magnesium measures the serum concentration of a mineral that acts as a cofactor in hundreds of enzyme reactions and stabilises nerve and cardiac muscle excitability. Most of the body's magnesium sits inside cells and bone, so serum reflects only a small pool. It speaks mainly for gut absorption and kidney handling.
No readings for this marker yet.
Lowered magnesium most often follows poor intake, chronic alcohol use, diarrhoea or malabsorption, loop and thiazide diuretics, or long-term proton pump inhibitor use. Raised values are less common and most often reflect reduced kidney clearance or magnesium-containing antacids and laxatives. Low magnesium can itself keep calcium and potassium from normalising, which is why it is checked when those fail to correct. A single result outside range warrants a repeat and a doctor's reading.
Haemolysis in the sample falsely raises the value, since red cells are magnesium-rich, and a normal serum level does not exclude depleted intracellular stores. Recent supplementation or antacid use shifts the result upward. Magnesium is interpreted together with potassium, calcium (total and ionized), phosphorus and kidney function.
Reference ranges are general adult values and depend on lab, assay, age and sex. For orientation, not diagnosis — discuss results with your doctor.