Magnesium, RBC Blood Test
Measures magnesium in red blood cells as one laboratory view of magnesium status.
- No doctor visit or referral needed
- Members pay our cost on every test, never a markup
- Tracked over time alongside your other results
- HSA/FSA eligible
- Typical results in 2-4 days · Reviewed by a real clinician
- Drawn at a CLIA/CAP-accredited lab near you · Find labs
Why people order the Magnesium, RBC Blood Test
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Weakness, cramps, tremor, palpitations, nausea, or fatigue
These symptoms are nonspecific. Acute or severe symptoms may require prompt clinician-directed serum electrolyte testing rather than RBC magnesium alone.
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Assess red-cell magnesium rather than serum magnesium
RBC magnesium is an alternative intracellular measurement with its own limitations. It is not proven to be superior to serum magnesium or to measure total-body stores.
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Follow a prior RBC magnesium result under comparable conditions
Using the same laboratory, unit, preparation, and supplement routine makes serial results easier to compare.
Who may consider the Magnesium, RBC Blood Test
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Low magnesium intake, gastrointestinal loss, or malabsorption
Diet and gastrointestinal conditions can contribute to low magnesium status, but no single magnesium test provides a complete assessment.
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Renal losses, poorly controlled diabetes, or heavy alcohol use
These contexts can affect magnesium balance and should be considered alongside kidney function, other electrolytes, and clinical history.
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Long-term proton-pump inhibitor use, certain diuretics, or other medicine-related loss
Some medicines are associated with magnesium depletion. Do not stop a prescribed medicine based on this test without clinician guidance.
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Monitor a clinician-directed magnesium plan when RBC magnesium is the selected marker
Interpret the result with diet, supplements, kidney function, gastrointestinal and urinary losses, medicines, symptoms, and other laboratory findings.
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Use extra caution when kidney function is reduced
Impaired magnesium excretion can increase the risk of accumulation, so supplement changes should not be based on this result alone.
Should I order RBC magnesium or standard serum magnesium?
Choose serum magnesium for the conventional measurement used in routine and acute clinical settings. RBC magnesium is a different red-cell measurement that may be considered for a selected intracellular or trend question. RBC magnesium is not proven to be a universally superior measure of magnesium status.
Is RBC magnesium appropriate for an acute electrolyte problem or for someone with kidney disease?
Not as a self-directed substitute for clinical evaluation. Acute symptoms, significant kidney disease, or a suspected serious electrolyte disturbance require clinician-directed testing, usually with serum electrolytes and kidney-function context. Do not wait for a routine RBC magnesium test when urgent assessment may be needed.
Should I add serum magnesium and kidney-function tests?
Add them when the goal includes conventional magnesium status, kidney handling, or a broader electrolyte assessment. Serum magnesium and kidney-function tests provide context that RBC magnesium does not. The appropriate combination depends on the clinical question rather than one universal panel.
Do I need to fast or change magnesium supplements before testing?
There is no universal fasting instruction for this product. Record magnesium-containing supplements, antacids, laxatives, and multivitamins, including their timing. Keep supplement timing and your usual routine consistent when following a trend unless a clinician intentionally changes them.
What members say on Trustpilot
What the Magnesium, RBC Blood Test measures
Measures magnesium in red blood cells as one laboratory view of magnesium status.
This test measures magnesium in packed red blood cells rather than serum or plasma. Current Labcorp, Quest, and BioReference mappings use LOINC 26746-8 and report mg/dL. Methods include inductively coupled plasma mass spectrometry and atomic absorption spectrometry. The unusual specimen is part of the product definition: the laboratory separates or processes red cells from an anticoagulated blood sample.
RBC magnesium is an alternative magnesium-status measure, not a direct measure of total-body magnesium stores and not a proven “long-term average” over the 120-day red-cell lifespan. Most magnesium is inside cells or bone, serum magnesium correlates poorly with total-body stores, and no single available method is considered satisfactory. NIH describes erythrocyte magnesium as one option among several and recommends combining laboratory results with clinical assessment.
This product is not serum magnesium, ionized magnesium, urinary magnesium, a magnesium-loading test, or a mineral panel. It does not determine the cause of an abnormal result and does not by itself establish magnesium deficiency or excess.
- Specimen
- Red blood cells
- Measures
- Mass concentration
- Reported biomarkers
- Magnesium
- Biomarker count
- 1 biomarker
- Fasting
- Special preparation needed (follow order instructions)
- Results
- On your Mito dashboard in 2-4 days, with your range explained
- Reference ranges
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Labcorp Test 080283 selected Quest Diagnostics Test 623 selected
Labcorp Test 080283
- All published populations 3.7-7.0 mg/dL
Quest Diagnostics Test 623
- All published populations 4.0-6.4 mg/dL
Your results
How to understand your Magnesium, RBC Blood Test result
Use the unit and RBC magnesium interval printed on the final laboratory report. Quest and Labcorp publish different method-specific intervals, and BioReference does not publish a numeric interval in its current public directory. Keep the same laboratory and assay when trending when practical. RBC and serum magnesium measure different compartments and use different specimen processing and reference ranges. Do not compare their ranges directly or convert between them.
Low RBC magnesium
A low result may support concern about low magnesium status, but it does not establish the cause or confirm whole-body magnesium deficiency. Interpret it with diet, supplements, kidney function, gastrointestinal and urinary losses, medicines, symptoms, serum electrolytes, and other relevant tests.
Within the provider's RBC magnesium interval
An in-range result describes this red-cell measurement under the performing laboratory's method and reference context. It does not prove ideal tissue magnesium or rule out every clinically important magnesium problem. No single available magnesium measure is definitive.
High RBC magnesium
A high result may reflect supplementation, altered handling or excretion, specimen or method factors, or another clinical context. It does not diagnose magnesium toxicity by itself. Reduced kidney function or acute symptoms increase the need for prompt medical interpretation before taking more magnesium.
How much the Magnesium, RBC Blood Test costs
Compare exact Mito member and non-member prices with recently checked comparable offers. Collection and lab fees are shown separately.
| Lab | Test price | Collection or lab fee |
|---|---|---|
| Mito member | $5.44 | $11.50 Added once per order |
| Mito non-member | $7.62 | $11.50 Added once per order |
| Goodlabs | $8.00 | $12.00 $12 per visit, included in the final checkout total |
| Marek Diagnostics | $20.00 | $10.00 $10 added at checkout for an individual biomarker or custom panel |
| DrSays | $19.99 | $9.99 $9.99 collection fee per order |
| Jason Health | $25.00 | $18.00 $18 lab collection fee per order |
| Ulta Lab Tests | $31.95 | $12.95 $12.95 standard draw fee; some locations may charge more |
| Walk-In Lab | $49.00 | $6.00 $6 per-order physician fee |
Mito prices come from the live catalog for the selected provider. Competitor prices were checked August 22, 2026. Published standalone item price plus the separately disclosed collection or checkout fee.
See the full Magnesium, RBC Blood Test cost comparison for provider details and comparison notes.
How it works
What to expect from your Magnesium, RBC Blood Test
- 1 Book instantly
Click, book, done. Choose a convenient lab location near you. Transparent, up-front pricing.
- 2 Quick lab visit
Testing to fit your schedule, usually 15 minutes or less. Walk-in and appointments available. Follow the preparation instructions for your order.
- 3 Results in 2-4 days
Your result posts straight to your dashboard as soon as the lab completes it.
- 4 Expert guidance
With membership, a clinician reviews your result and a personalized action plan follows, with clear next steps.
Every result comes with a plan
A number on its own does not tell you much. Membership is what turns it into next steps, and keeps track of what changes.
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Insights that connect the dots. A clinician reads your whole picture, not one result in isolation, connecting family history, past results, and lifestyle into clear next steps.
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Your personalized action plan. Nutrition, supplements, and training in one clinician-reviewed protocol, updated as your results change.
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Track your trends. Upload results from any lab and see each biomarker trend over time, so you know what is working.
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Never miss a recheck. Mito tells you what is worth retesting and when, then reminds you so nothing slips.
Magnesium, RBC Blood Test testing you can trust
Run to clinical-grade standards
- Processed at the same CLIA and CAP-accredited national labs your doctor uses
- Order online, no doctor visit or referral needed
- Your data is encrypted, handled under HIPAA, and never sold
Overseen by our Care Team Lead
Every result, including your Mito Brain analysis, is checked by Rhonda Collins, FNP-C, our Care Team Lead and a board-certified Family Nurse Practitioner with over 15 years of nursing experience across cardiac ICU, primary care, and dermatology.
Meet RhondaEverything your health needs,
in one membership
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Every test at our cost
Members pay our cost on every test, with lab fees passed straight through. The full receipt is itemized, never padded.
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Continuous tracking, all in one place
Upload past labs and watch your trends over time. Every marker and visit lives in one longitudinal record, so all your care stays together.
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Year-round clinician support
Text anytime and get clinician-reviewed answers. When you want to go deeper, 1:1 consultations are available at affordable rates.
Common Magnesium, RBC Blood Test questions
Is RBC magnesium better than serum magnesium?
Does a normal serum magnesium mean RBC magnesium will be normal?
Does this test measure magnesium stored throughout the body?
Can this result determine a supplement dose?
Do I need to fast?
Can I compare results from different laboratories?
What if the result is very high or I have kidney disease?
Can specimen handling affect the result?
How do availability and prices vary by state?
Available in all 50 states and Washington, DC.
| States | Provider | Availability | Member price | Non-member price |
|---|---|---|---|---|
| All states and DC except NJ, NY, and RI | Labcorp | Available | $5.44 | $7.62 |
| All states and DC except NJ, NY, and RI | Quest Diagnostics | Available | $8.77 | $12.28 |
| NJ, NY, and RI | BioReference | Available | $12.96 | $18.15 |