$11.00
Priced per marker, with baseline labs included. You’ll see your total before you pay.
Brain & nervous system
Magnesium (red blood cell) test
Magnesium inside red cells; may reflect long-term tissue stores better than serum magnesium.
At a glance
In about 5 days
Most results are ready in about 5 days. Some specialty markers can take up to 21 days.
Check before your draw
This marker has no preparation tag, but it can still need preparation. Contact us before your draw if you’re not sure.
Walk in at Quest
Your lab order arrives by email. Most Quest locations take walk-ins, so bring it with a photo ID.
What it measures
Rather than the fluid part of your blood, this measures magnesium inside your red blood cells. Some doctors use it to get a fuller sense of your body’s magnesium stores.
Why it matters for women
Migraines are far more common in women, and low magnesium may be linked to them as well as to muscle cramps. A standard magnesium test can look normal even when stores run low, so this test may add another view. There’s no single perfect measure of magnesium, so results are best read with your symptoms.
You might check it if…
- your regular magnesium result was normal but cramps or twitches continue
- you get frequent migraines
- you’ve taken heartburn medicine or water pills for a long time
What your result may mean
High Magnesium (red blood cell): what it may mean
High RBC magnesium can reflect supplement use or a steady, healthy intake of magnesium over time. This test looks inside red blood cells rather than in the fluid part of your blood, so it may not match a standard serum result. Magnesium antacids and laxatives can add to your intake, and kidney disease can make extra magnesium harder to clear. A high value may not be worrying by itself, and you may feel nothing. If you take magnesium for migraines, cramps or PMS, a clinician may want to know how much.
Low Magnesium (red blood cell): what it may mean
Low RBC magnesium may mean your body's magnesium stores are running low (tissue-level deficiency), even when a standard serum result looks normal. It can happen with long-term poor intake, alcohol, water pills (diuretics), proton pump inhibitors or ongoing stomach and bowel losses. Some people may notice muscle cramps or tiredness, and low magnesium may be linked to migraines and PMS in women. There is no single perfect measure of magnesium, so a clinician may read this result with your symptoms and serum level.
Get started
Stop guessing. Start testing.
Answer a few questions. We’ll suggest tests linked to how you feel, with a clear price for every test.
No insurance required · HSA/FSA eligible · No subscription
These notes provide context and do not diagnose a condition. Not yet available in NY, NJ, RI, HI, ND, SD or WV.