RBC magnesium test comparisons

The RBC magnesium test provides useful but limited information as a guide to magnesium therapy. Here's the logic: when the RBCs are formed in the bone marrow (2 1/2 million per second!!) they incorporate the mag that is in the marrow blood. Whatever magnesium is there at that time is the magnesium the RBCs will have, and will even lose some as they age (1). Unlike 'metabolically active' cells, RBCs have no 'mechanism' for accumulating more mag (2). RBC mag status does not correlate with 'metabolically-active' cells' mag status, e.g. atrial muscle cells.

The magnesium in a blood sample taken from a vein is in equilibrium with mag in bone and usually varies little (homeostasis). More than half of the body's mag is in bone, only 0.3% is in the serum (3). Furthermore, a significant percentage of blood mag is bound to substances such as proteins, and is therefor metabolically inactive (4). Unless the active, ionized Mg++ fraction is measured, this test has little or no meaning.

Intracellular magnesium (mag in metabolically-active cells) is difficult to assess. ExaTest (5) by Intracellular Diagnostics, Inc. employs excellent science and non-invasive methodology, but unfortunately their quality-control is lacking, making results difficult and dangerous to trust. Another way is to measure mag in metabolically-active WBCs (leukocytes - white blood cells), but lack information about availability, also a reference range.

Comparing reference ranges for these three magnesium status tests:

- Venous blood mag test. 1.7 - 2.5 mg/dl: level in sample drawn from a vein. Total of free (active) and bound (inactive).
- RBC mag test.......... 4.0 - 6.4 mg/dl: level in bone marrow blood at the time RBCs were formed.
- Exatest IC mag test. 41.2 - 48.6 mg/dl: level within 'metabolically active' cells.

1. "Young RBCs contain more magnesium than do old RBCs". Drs. Mildred Seelig and Andrea Rosanoff, The Magnesium Factor, p. 31.
2. For complete information on RBCs: [en.wikipedia.org]
3. Herbert Mansmann, MD [barttersite.org]
4. [www.clinchem.org]
5. [exatest.com]

Hello Erling,

I can't query what you have said but in the end in an imperfect world I have chosen RBC due to lacking a better practical choice..

I often think of the saying''in the land of the blind the one eyed man is king''

Alex

Exatest IC mag test. 41.2 - 48.6 mg/dl:

Erling, when I took the Exatest 6 or so years ago, the bottom end of the range was 33 or 34, as I recall. Ditto, from memory, what Mike F posted when he took his test more recently.

George

Hi George,

Thanks for checking. Exatest shows the range to be 33.9 - 40 mEq/L. Converting this to mg/dl for comparing with the other ranges it comes out just a bit higher. The multiplier 1.215 is from Dr. Mansmann's site. I was lazy and just assumed he was right. I do appreciate his comment: "The situation is somewhat confusing because laboratories and medical writers use three different unit methods to record the values of Mg in tests." Why?

This way the steepness of the EC to IC concentration gradient becomes obvious, maybe about 20:1?

Erling

Thanks, I wasn't focused on the different units!

Erling - thanks for taking the time to post this for us.

I'm confused as to how one draws blood and then gets a RBC bone marrow blood result. I thought RBC bone marrow involved extraction directly from the marrow itself in a painful process. I'm confused at item #2 in your list.

In the magnesium by Dr. Burford-Mason on magnesium, she says:

" No studies have shown that red blood cell magnesium or serum Mg either one are good reflectors of whole body magnesium status. In fact if you talk to biochemists in hospital laboratories, they’ll tell you the only people who ever have a low serum magnesium are those who are very, very ill or are in bed all the time. Physical activity recycles magnesium out of bones as well.

If extremely low – be concerned but if high or mid-range, it doesn’t tell much because 5 minutes late, it can be completely different. So it’s much easier – no waiting on lab results to just question patients and you can determine from physical signs – all related to full function or mal-function of skeletal, smooth or cardiac muscle … if they have constipation, muscle cramps, fasciculations…you just know they need more Mg. (I add AF to this list- J )

The Mg doesn’t stay put in a red cell once the red cells is formed so it isn’t a long-standing indicator of Mg status – it’s only 1% of magnesium in blood; the rest is divided between bone and about 30% in bone can be quickly released and dumped into blood if needed for balance if that 1% goes down. "

As we have discussed, the ExaTest seems to be the most accurate reflection of magnesium, especially in cardiac cells which is our target interest... but as we've previously discussed, there is concern with the management at Intracellular Diagnostics.

Another clip by Dr. Burford-Mason:

Because magnesium moves between compartments and across membranes, laboratory assessment of magnesium status is notoriously difficult.68 A drop in serum magnesium is quickly normalized from bone or intracellular stores. Therefore, serum or plasma magnesium is not a reliable indicator of magnesium status. Depletion of muscle magnesium has been shown in the presence of normal plasma, red blood cell, or mononuclear blood cell magnesium concentrations.68,69

Intracellular ionized magnesium measured in sublingual epithelial cells has been promoted as a reliable marker of tissue magnesium stores.70 Sublingual epithelial cells are thought to approximate tissue stores because of their rapid turnover time (<3 days), and are easy to access. In cardiac patients undergoing bypass surgery, magnesium was lower in such cells compared to healthy controls, where no difference in serum measurements was observed. Magnesium content of sublingual cells correlated well with atrial biopsy specimens taken from the same patients during surgery.70

However, the test is not routinely available, and as yet there are
no published data to support the reliability of the test in less seriously ill patients. "

68. Dewitte, K., Stockl, D., Van de Velde, M., and Thienpont, L.M., Evaluation of intrinsic and routine quality of serum total magnesium measurement, Clin. Chim. Acta., 292, 55–68, 2000.
69. Arnold, A., Tovey, J., Mangat, P., Penny, W., and Jacobs, S., Magnesium deficiency in critically ill patients, Anaesthesia, 50, 203–205, 1995.
70. Haigney, M.C., Silver, B., Tanglao, E., Silverman, H.S., Hill, J.D., Shapiro, E., Gerstenblith, G., and Schulman, S.P., Noninvasive measurement of tissue magnesium and correlation with cardiac levels, Circulation, 92, 2190–2197, 1995.

Erling - sorry... I either read too quickly or with eyes half open this morning...
I now see what it says about bone marrow blood collected.. Sorry for confusing this issue. Jackie

Jackie, thanks for your replies -

In the Burford-Mason quote there is a part that needs updating, as it was obviously written before the advent of ExaTest as a means for assaying intracellular magnesium. Note Dr. Burton Silver's name as author of the referenced 1995 journal article, the founder of Intracellular Diagnostics/ExaTest:

"Intracellular ionized magnesium measured in sublingual epithelial cells has been promoted as a reliable marker of tissue magnesium stores.[70] Sublingual epithelial cells are thought to approximate tissue stores because of their rapid turnover time (<3 days), and are easy to access. In cardiac patients undergoing bypass surgery, magnesium was lower in such cells compared to healthy controls, where no difference in serum measurements was observed. Magnesium content of sublingual cells correlated well with atrial biopsy specimens taken from the same patients during surgery.[70]

However, the test is not routinely available, and as yet there are
no published data to support the reliability of the test in less seriously ill patients. "


70. Haigney, M.C., Silver, B., Tanglao, E., Silverman, H.S., Hill, J.D., Shapiro, E., Gerstenblith, G., and Schulman, S.P., Noninvasive measurement of tissue magnesium and correlation with cardiac levels, Circulation, 92, 2190–2197, 1995.

(The full text of this article is available at the ExaTest website along with many others of relevant scientific interest: [www.exatest.com])

Erling - the piece quoted was written for a 2009 publication. Dr. Burford-Mason practices in Canada which may account for the lack of her experience with Exatext since they can't order it there. I'm just guessing about why she made that observation. Jackie

Thanks Jackie -

More important: Dr. Burford-Mason was wrong in saying (in 2009) that "as yet there are no published data to support the reliability of the test in less seriously ill patients." How can that be?

It seems that ExaTest technology has been in continuous use by astronaut crews on the International Space Station ever since its first occupation in '99, based on science published in 1990* and earlier. It was experimentally used on space-based Skylab in the '80s. By now this is old, proven, extremely beneficial technology. I sure do wish they'd get their QC act together so we could recommend it's use.

*Application of a Novel Method to Measure IntraCellular Ions as Applied to Space Flight, NASA, 1990:
[www.exatest.com]



Erling

Don't know. What can I say? One published study by Silver and group - maybe she was suspect of that study? I have no way of knowing. Jackie

Any other source of an Exatest-like magnesium count? Or are they the only game in town? If not available in Canada I am happy to visit a stateside MD (we have several in the family) to get the test done but it is at my sole expense; whereas a similar test north of the 49th. in Canada would be covered by government and/or private health insurance if prescribed my an MD. Out of interest and budgeting, what is the cost of the EXA test for cellular magnesium?
Thanks in advance.

Murray - Last February, there were some threads running on Exatest...
go back to the BB session before this current one... You should do a search to call up the many opinions on Exatest.

Here's one link where the costs at that point in time were outlined.

There have been people in Canada who have tried to get Extests and apparently it's not possible to transmit across the border.

<[www.afibbers.org];

Jackie

Jackie
Thank you for that reference and I am pouring over the information; I think that I am on the right track but am unsure of dosing quantities. I am thinking that it will take some messing around with in order to bring things together. Tooo much toooo fast.

I can tell you that my pulse graphic on the pulse oximeter has changed for the better, showing a more steady rhythm and volume although not by any means corrected. But something MUST be happening here, as I am also noting that my diabetes, incredibly, is melting away as well. Go figure. I am getting confused. Blood glucose levels that were all over the place are now settling in at around 6 which is about perfection. I may have to eliminate the Metformin completely (I am down to 500 mg b.i.d. which is a less than therapeutic dosage already) as my blood glucose level set off the alarm on the glucometer at 3.9 shortly after my experiment this evening; eating a whack of rice and a whack of Italian fruitcake (which I never do but it was yummy). I had to go and eat some more (not great) in an attempt to bring the blood glucose level up and I think I am fine now. I am off to check it again.

I honestly believe that this Janumet and Caduet that my endocronologist pushed on me (replacing Metformin) both dropped my BP as low as it has ever been and may have irritated my pancreas, letting loose Lord knows what sort of domino effect. I had symptoms of Pancreatitis when he first pushed it on me... three months later it was essentially "I have thousands of patients on it. Take it or find another endocronologist". I should have run but I stuck it out on Janumet/Caduet for three weeks, felt so awful after the three weeks that I stopped taking it, went back to Metformin and Gluconorm as required and asked my GP to monitor my Hemoglobin A1c for me. And lo and behold my blood glucose is not only as good as it has ever been; my diabetes may be about gone!? I can't figure this one out.

The problem is that I have gone back to Metformin AND have begun the supplements program. I am strongly believing that the supplements are having a huge positive effect on my diabetes. And something is having a positive effect on my AFib although it is very early to really tell.... I'd bet money on it.

The second half of the supplements, which I describe in my thread "supplements/diabetes?" have arrived and I am unsure of where to go with this next. Sit tight and see what happens or begin using the second half of the supplements and see what happens.

The book reference on that old thread is fascinating and I need to spend time consuming and digesting it.... But like I say, I'd be betting my last dollar that I have been magnesium shy for years as well as dehydrated and potassium shy, etc.

My post on the other thread will show you all of the medications that I have been taking/am taking as well as the supplements.

It's off to bed for me. A good night of sleep is needed at this end and our 17 year old, who has his pilot's wings and is up for an instructor rating in the spring when he turns 18.... is taking driving lessons! And is a holy terror on the roads as there are no rudder peddles in the car. And our 19 year old daughter is home from university for the holidays and break. And the wife is booked for surgery in February immediately following ME being paddled, etc. Lots of excitement to come.

My main project for tomorrow is to log onto the website for the guys that manufacture daily pill organizers and find one large enough to hold all of the supplements for each day. The pharmacy has one but it is organized by the week (go figure - they have tons of them and the Dollar Store has the same ones they are selling for $10 for $1.... methinks they don't sell too well and I can't find daily organizers in any of the stores; thank goodness for the internet and online shopping.)

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