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Are You Missing Magnesium Because of Meds?

When is the last time you were tested for magnesium? Doctors don't always check for missing magnesium. This mineral is crucial for good health

When you go to see a doctor for a routine physical, you can expect basic tests. You will be weighed and have your blood pressure measured. The doctor or nurse practitioner will listen to your heart and lungs and check reflexes. Chances are good you will have blood drawn to check for blood cell abnormalities, cholesterol, blood glucose and electrolytes like sodium and potassium. Sadly, routine electrolyte panels are often missing magnesium.

Potassium Gets Plenty of Attention:

Medical students are taught the importance of minerals such as sodium and potassium. They learn to advise patients to lower their salt intake to keep their blood pressure under control.

When doctors prescribe diuretics for hypertension or heart failure, they are supposed to monitor potassium levels. That’s because such medications can deplete the body of potassium along with excess fluid.

Maintaining potassium within a narrow range is essential for good health. Too much or too little can lead to fatal heart rhythm changes. Muscles and nerves also require the right amount of potassium to function normally.

Missing Magnesium Is a BIG Ooops!

The mineral that often gets overlooked is magnesium. It is not part of a routine blood test and it is often forgotten during an annual physical.

We don’t understand why magnesium doesn’t get the respect it deserves.

According to the National Institutes of Health Office of Dietary Supplements:

“Magnesium is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation.”

That’s just for openers. Magnesium is essential for proper carbohydrate metabolism. For your muscles to contract optimally you need magnesium. This mineral plays a powerful role in cardiovascular health.

And let’s not forget bone health. Most people think of calcium when they think of bones.

But according to our colleague, Tieraona Low Dog, MD:

“Magnesium is important for bone health, in part because of its role in the regulation and metabolism of calcium and vitamin D, but also because it is one of the key minerals that make up our bones. As magnesium levels in bone decrease, bones become more brittle.”

Testing for Missing Magnesium:

Doctors may request a serum magnesium test if they suspect deficiency. Some experts argue, however, that measuring magnesium in red blood cells gives a more accurate assessment.

We can’t resolve the controversy in this article.

However, here are some key points from an article published in the journal Open Heart (Jan. 13, 2018)

“Because serum magnesium does not reflect intracellular magnesium, the latter making up more than 99% of total body magnesium, most cases of magnesium deficiency are undiagnosed.

“Magnesium deficiency can be present despite normal serum magnesium levels…our normal range of serum magnesium is inaccurate and that serum magnesium levels at the lower end of normal likely suggest marginal magnesium deficiency. Indeed, ‘The magnesium content of the plasma is an unreliable guide to body stores: muscle is a more accurate guide to the body content of this intracellular cation’.”

“Magnesium deficiency is extremely hard to diagnose since symptoms are generally non-specific, there are numerous contributing factors, and there is no simple easy way to diagnose magnesium deficiency.”

The authors suggest ways to measure magnesium deficiency. They state that:

“retention of magnesium load (intravenous or oral) after its administration is likely the best indicator of magnesium deficiency.”

This retention test requires normal kidney function, though. People with abnormal kidney function should NOT get this test!

According to these authors, a muscle biopsy to determine muscle magnesium content is the second favorite test, though it seems a bit invasive to me.

Less reliable, but positioned above serum magnesium is a hair test for magnesium. If you go to the original article you will discover several other ways doctors can test for magnesium levels.

Are You Missing Magnesium?

Nearly half of American adults got less magnesium than recommended in their diets in a large survey (Nutrition Reviews, March 2012). Unfortunately, magnesium-deficient people may be more prone to type 2 diabetes, metabolic syndrome, high blood pressure, cardiovascular complications, menstrual cramps, migraines, depression, osteoporosis, asthma and colon cancer.

When Magnesium Levels Are Low:

Symptoms of missing magnesium can be subtle. They may include weakness, palpitations, insulin resistance, fatigue, migraines, slightly elevated blood pressure, muscle cramps and menstrual cramps.

When the deficiency is pronounced, the symptoms can become more severe. They may include dangerous heart rhythm disturbances, heart disease, heart failure, calcification of soft tissue, cataracts, nausea, vomiting, numbness or tingling of hands or feet, seizures, personality changes, depression and coronary spasms.

Dietary Sources of Magnesium:

The food sources richest in magnesium may not be on everyone’s menu: pumpkin seeds, chia seeds, almonds, spinach, cashews, peanuts, shredded wheat and soy milk. In general, legumes, nuts, seeds and whole grains are good sources. Oh, and let’s not forget dark chocolate!

Drugs That Lead to Missing Magnesium:

Even when people are very conscientious about their diets, they may be taking medications that can undermine healthy magnesium levels. Diuretics like furosemide (Lasix), bumetanide, chlorthalidone and hydrochlorothiazide often deplete magnesium along with potassium.

Proton pump inhibitors (PPIs) for acid reflux such as dexlansoprazole (Dexilant), esomeprazole (Nexium), lansoprazole (Prevacid), omeprazole (Prilosec), pantoprazole (Protonix) and rabeprazole (Aciphex) can also lead to low magnesium levels, presumably because they interfere with absorption.

Immunosuppressants such as sirolimus (Rapamune), tacrolimus (Astagraf XL, Envarsus XR and Prograf) and cyclosporine (Neoral, Sandimmune) increase magnesium excretion by the kidneys. This results in lower levels of magnesium in the body.

The heart medicine digoxin (Lanoxin) can also reduce magnesium levels. This could become especially dangerous in combination with PPIs or diuretics (Nephron, Feb. 2018). 

Readers who are taking any of these medications should ask about magnesium monitoring. Magnesium supplements may be necessary. Anyone with impaired kidney function, however, should not take magnesium supplements!

Dr. Low Dog’s Wonderful Book:

If you would like to learn more about magnesium and medications that can deplete the body of this essential mineral we encourage you to check out Dr. Low Dog’s wonderful Book:

Fortify Your Life: Your Guide to Vitamins, Minerals and More

In it you will learn which medications deplete the body of essential nutrients. You will also learn more than you can ever imagine about nutraceuticals, supplements and laboratory tests. If it is not in your local library, you can find the paperback edition at this link.

You can also listen to Dr. Low Dog and Dr. Carolyn Dean (author of The Magnesium Miracle) on our podcast:

Show 969: Magnesium the Neglected Mineral
Magnesium is essential for good health, yet it gets too little attention and ordinary diets may come up short.

Share Your Story About Missing Magnesium:

Have you ever been tested for magnesium levels? Were you ever found to be low? Do you take magnesium supplements? If so, have they made a difference? Please add to our database by putting your story in the comment section below. If you think this article might be helpful for someone, please share it via email, Facebook or Twitter by scrolling to the top of the page and clicking on the appropriate icon. Thank you for supporting our work.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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  • DiNicolantonio, J.J., et al, "Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis," Open Heart, Jan. 13, 2018, doi: 10.1136/openhrt-2017-000668
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