When is Magnesium Test actually useful?

A magnesium test (e.g., serum magnesium) is clinically useful when deficiency is suspected (symptoms like muscle cramps, fatigue, arrhythmias) or in risk groups (elderly, diabetics, chronic illness, alcoholics, certain medications). In healthy individuals without symptoms, routine testing is often not beneficial because the body tightly regulates serum levels, and deficiency may only be detectable in tissues or intracellularly. Direct-to-consumer DNA tests for magnesium-related genes (e.g., TRPM6) have limited evidence and are not clinically recommended. A targeted history and possibly a 24-hour urine magnesium or RBC magnesium test are more informative. Caveat: many commercial tests overstate usefulness. Evidence: human-moderate.