Mg & K serum v. Intracellular?

Just a quick Q in light of current discourse here and in the CR where there is lots of talk about the importance of K and various individuals are discussing their own serum levels of K. I think we all appreciate the fact that a serum Mg offers little in the way of an indication as to one's intracellular stores of Mag - Is this also the case for K?? My last serum K was OK at 4.3 but I'm left wondering whether this reading could be masking an intracellular deficiency.

TIA,

Mike F.

Mike,

This question has come up before. Are blood K levels representative of intracellular K levels?

I don't think the problem with K is as significant as with Mg, but it's not as solid an indicator of intracellular levels as blood Na and Ca are.

There has been a general trend in mainstream medicine to raise the acceptable range of normal wrt serum K. Please visit
[www.medscape.com]|1343260868989756938/184161393/6/7001/7001/7002/7002/7001/-1
for an excellent discussion of this in an article entitled
Importance of Potassium in Cardiovascular Disease

To further underscore this growing sentiment (less concern about excess K and more about insufficient K), I might mention that Dr. Lam (www.lammd.com) in his recent book states that daily intake up to 15 gm of K is OK.

PC

PC - 15 grams via food sources or chemicals? Jackie

For anyone who had trouble [as i did] highlighting this very long URL so as to cut and paste it, the article can be found by typing the title into google, in double quotation marks.
PeggyM

Jackie,

That's a good question. Unfortunately in preparation for our move a lot of things have been already packed, including Lam's book.

However, I'm sure none of the experts would be comfortable, much less recommend, popping 150 99mg tabs of K+. But supplementing something in the range of 500-1000 mg during the day, assuming normal renal function, should be OK. Although natural sources would be best, K is K, whether eating a 5 inch banana (1 milliequivalent K/inch of banana) or popping two tabs of K. This translates to only 200 mg K, since 1 meq of K = 40 mg K.

Although I try to eat several bananas/day, I supplement with something under a gram of "chemicals"/day.

I'm not sure what would happen if I did a Paul Newman (Cool Hand Luke)and ingested 15 gms K from natural sources. Although this was Dr. Lam's upper limit, he doesn't seem to be too worried about such a thing.

PC

PS Excellent post on potassium, Jackie. This is the real culprit as far as AF is concerned. It's just that magnesium is so critical in maintaining the right K balance.

PC - Well thanks to you and Hans for hammering away at the reason why we become deficient.

On the supplement portion of potassium.... I think Dr. Murray or someone says the problem with any large quantity of chemically-derived potassium, it is the chloride or bicarbonate portion from the complex....that becomes the problem, so if one takes supplements... is it best to look for a form such as potassium citrate?

What form do you use?

I haven't seen Cool Hand Luke in many, many years... what did he do OD on potassium? Bananas? Enlighten.


Even your 1,000 mg range with the bananas and the supplements falls very short of what Dr. Murray suggests our daily needs are. If one goes to the food values and adds up K, that's alot of groceries required to = 4 - 5 grams a day.

Jackie

PC - another question on serum levels of potassium. You mentioned they were probably reliable indicators versus serum magnesium which is not...

I recall you checked into the Exatest method of magnesium evaluation, do you remember if they claimed that potassium could also be evaluated that way and if it was more indicative of cellular levels?

And..one more.... there has been discussion about red blood cell analysis for magnesium.... I believe they call it packed RBC..... can you offer an opinion as to the reliability of that say versus... Exatest?

Thanks

Jackie

Jackie, what we got here is a failure to communicate. I bet ol Luke could eat 60 hard boiled eggs in an hour. It was eggs, not potassium!

Anyway, the potassium has sure helped my "flutters"! I'm a believer.

John

Jackie,

Thank you.

Dr. Murray may well be right, especially wrt KHCO3. I suppose it is best to mix your forms of K supplements (and others as well). I usually take potassium gluconate, but also have potassium chloride. The latter comes in 20 meq tabs (=800 mg K/tab) and requires a prescription. I'm a little surprised that the prescription form containing that much K would be in the KCl form, if KCl were a possible problem. However, I plead ignorance on that.

Cool Hand Luke was a classic movie set in the old South in which Paul Newman was serving time on a chain gang. Back in the prisoner bunkhouse there was a scene in which Paul and some other prisoner worked a bet with the others on how many hard boiled eggs he could eat in one sitting. I don't remember the exact number, but it was way over 50.

I know I couldn't possibly put away forty 10 inch bananas (the equivalent of about 15 gm of K) in 24 hours much less one sitting.

So, you're absolutely right. Even though I eat plenty of other K containing foods (esp. avocados, cantalope, mushrooms, oranges), I fall way short of the recommended dietary intake of K. But I'm a lot better than I used to be and I suspect better than most in the general population.

That's why urinary Mg and K wasting has got to be occurring. The only way to really nail this down is to compare a critical mass of LAFers and normals. Measure intracellular levels before a designated IM or IV dose of Mg and monitor subsequent 24 hour urinary Mg excretion. Dietary intake would have to be nil or evaluated separately.

This approach is close to the 24 hour Mg challenge test, which seems to be highly regarded as a method for determining Mg deficiency. I believe intracellular analysis is more accurate than evaluating Mg in packed rbcs and offers the best of both worlds when combined with the 24 hour Mg challenge test.

But alas, such an approach would be fairly expensive. The intracellular Mg alone would run $175 US and is not even available in Canada. My email entreaty to Burton Silver last summer to do just such a trial fell on deaf ears.

Regarding intracellular K, I lifted the following from the exatest site:

"The extent of potassium loss in tissue cannot be accurately assessed by serum measurements alone. Adequate measurements of TISSUE and serum potassium are essential in determining cellular fluid balance. Maintenance of cardiac skeletal and smooth muscle and nerve function depends on adequate potassium gradients between intra and extracellular spaces. All neuromuscular activity is dependent on both sodium and potassium for maintaining the electro-potential in both nerves and muscle. The major means of regulation of potassium is though the kidneys, as well as the gastrointestinal tract and skin. Serum potassium may not reflect the tissue levels, when potassium is given. EXA testing provides information before a crisis of potassium loss or excess is identified in serum. Lack of magnesium is a major factor in loss of potassium. RDA for POTASSIUM is 1875-5625 mg."

It would be nice if there were such a thing as a 24 hour K challenge test, but I don't think many will feel comfortable injecting any significant amount of K IV. After all, it is used on death row as a lethal injectable.

So, there you have it.

PC

Cool Hand Luke ate eggs, not bananas. Loved the movie, and I hope we don't have "a failure to communicate" about potassium.

Jackie,

That was supposed to be a thank "YOU", not a thank you.

PC

Okay - to all - it was eggs. I can't remember that portion of the movie and I haven't seen any of the reruns on video. I do remember that Paul was very handsome! Haven't forgotten that.

Either way, eggs or bananas...thatsalotafood. Thanks for telling me how it was.


The point being here then - is it is unlikely that many of us consume
4 or 5 grams of food based potassium in a day. Possibly, we don't need that much to stay out of arrhythmia, but to correct a deficiency problem and get the heart stable, it may be necessary to do some heroics with potassium intake be it from food, supplements or a combination.
Jackie