What Causes Abnormal Potassium Levels?

If you have elevated potassium (K+) levels and are put onto a low potassium diet, how long would it take to see results in your lab work?

A mineral crucial to all life. potassium  (or K+) is the principle cation (positively charged mineral ion) inside our cells. In the blood and other fluids outside of cells, potassium concentration is much lower than it is inside the cells. Other important cations are sodium (Na+), calcium (Ca++), iron (Fe++) and magnesium (Mg++). The major cation in the blood is sodium, which is present in low concentrations inside cells.

Measurement of sodium and potassium is commonly included in the panels of chemical tests that doctors routinely do, although many doctors — myself included — would question whether this practice is a good one. The potassium concentration in blood is generally closely regulated and kept between 3.5 – 5mEq/L. Our kidneys are very efficient at excreting potassium when the level is too high, so it would be most unusual for someone who is otherwise healthy and not on any medication to have an elevated K+ level in the blood.

Keeping the K+ level within the normal range is crucially important because high K+ levels can cause abnormal cardiac or heart rhythms, and sudden death. I believe that the drug used in executions by lethal injection is potassium chloride (KCl).

It may seem like you have a serious problem and really need to work on it, but I doubt if you have any illness at all unless it is kidney failure, which you would have known and mentioned, and which would have produced many other abnormalities on your blood tests; or you are on one of the drugs that can raise potassium. I say this with some assurance because a high K+ level on routine tests is probably the most common false positive test result that we see. Since potassium is high inside cells, and low in the serum (the non-cellular liquid part of the blood), if any of the red cells which make up about 40 percent of the blood volume have broken up, spilling out their potassium, the test will be falsely high.

This is common if the blood tube is shaken vigorously, or allowed to sit around for awhile before the cells and the serum are separated. Good laboratories will often comment on their reports that a specimen was hemolyzed, meaning that many red cells had broken up, and that some test results might be affected.

Drugs that can lead to high K+ levels include ACE inhibitors and beta blockers, both of which are commonly used to treat hypertension, and non- steroidal anti-inflammatory. It would be possible for someone to have a truly elevated K+ level if they were on one or several of these drugs, and consumed a high potassium meal (lots of meat) especially if a salt substitute which contains KCl were used on the food, and then went in for their blood test. Even this combination would be unlikely though to raise the level to a dangerous degree, and if the person had normal kidneys, they would quickly correct the problem.

I have only seen this type of elevation once in an elderly woman who did have considerable kidney failure, and a change in her medications was all that was necessary to bring the K+ back in line. Advanced Addison’s disease, caused by destruction of the adrenal glands, is commonly associated with a high serum K+ level, but the weakness, darkening of the skin and weight loss caused by this disease would make the diagnosis pretty obvious.

A much more common problem is low K+ (hypokalemia), usually as a result of diuretic treatment of hypertension. Some diuretics, commonly referred to as “water pills” cause the kidneys to excrete too much potassium. Doctors will often prescribe a potassium supplement to replace this loss. Other causes are diarrhea, vomiting and laxative abuse. It is not uncommon to see a low K+ in bulimic people who are abusing laxatives and diuretics to lose weight. The first symptom of low K+ is weakness, which may become severe.

Unless you have kidney failure, or are on some of the drugs I mentioned I doubt that you have a true elevation of the K+. Checking with your doctor about your kidney function should be reassuring, and if it is normal, a repeat test with care to separate the serum and the cells promptly will probably come back with a normal level of K+.

The information provided on Health Search Online is for educational purposes only and is not a substitute for medical advice, diagnosis or treatment.