RBC Mg
A more accurate measure of true magnesium status than serum magnesium.
What is it
Red blood cell magnesium reflects intracellular magnesium stores and is considered more accurate than serum magnesium, which represents only a small fraction of total body magnesium.
Why it's measured
RBC magnesium has been studied as a marker of functional magnesium status in research on cardiovascular health, neuromuscular function, and sleep.
Reference range
Standard laboratory reference
4.2 – 6.8 mg/dL
Reference ranges vary by laboratory. Your individual reference range will appear on your test report and should be interpreted by your physician in the context of your overall health profile.
Where does your number land?
—
Drag to your own RBC Magnesium result.
Educational only, not a diagnosis. Ranges vary by laboratory. See which panel includes RBC Magnesium.
What results may indicate
Elevated
Generally not clinically concerning.
Lower
Has been associated with neuromuscular symptoms, sleep disturbance, and cardiac arrhythmia susceptibility in research literature.
These associations are general. They are not a personal diagnosis or prediction. Discuss your individual results with your physician in the context of your full health profile.
When it's measured
Used when functional magnesium deficiency is suspected and serum magnesium is unclear.
Related markers
Common questions
Red blood cell magnesium reflects intracellular magnesium stores and is considered more accurate than serum magnesium, which represents only a small fraction of total body magnesium.
It's one of the markers used to build a fuller picture of your health. On its own it tells you very little, so it's most informative when reviewed alongside related markers.
It's measured from a standard blood draw at Quest or LabCorp. RBC Magnesium is one of the markers included in the OPTML Apex Panel, where your results are read across systems and reviewed by a U.S.-licensed physician.
Reference ranges vary by laboratory, and a single value rarely tells the whole story. Review your result with a physician in the context of your other markers, symptoms, and history.
RBC Magnesium is one signal among many. Answer a few quick questions and we’ll point you to the panel that fits.
Related symptoms
A symptom is a signal, not a diagnosis. These guides explain what the evidence shows and the blood markers, including this one, that help find the cause.
Measured in
A complete look at your heart, hormones, metabolism, inflammation, and longevity systems — drawn at Quest or LabCorp, reviewed by a U.S.-licensed physician.
Find the right panel →This information is for general educational purposes only and is not medical advice. Lab results alone are not intended to diagnose, treat, or cure any condition and do not replace the advice of a healthcare provider. OPTML does not offer medical advice, a diagnosis, medical treatment, or any form of medical opinion.
OPTML offers compounded semaglutide and tirzepatide, prescribed and overseen by U.S.-licensed physicians. Compounded drug products are not approved or evaluated for safety, effectiveness, or quality by the FDA. OPTML is not associated with, endorsed by, or affiliated with the manufacturers of FDA-approved branded weight-loss medications, and does not sell or supply those branded products. Anyone interested in an FDA-approved branded medication should consult a licensed healthcare provider or pharmacist. Individual results vary; no specific result is promised, and weight management requires ongoing medical guidance.
The whole picture in one sitting: who it suits, what the labs decide, what the first year actually looks like. Every clinical claim is cited.
How to protect lean mass while losing weight on a GLP-1.
Double-check your email. A typo means we cannot reach you or resend your guide.
We will send occasional emails you can unsubscribe from at any time. See our Privacy Policy.