DEAR DR. DONOHUE: In the past you raised the subject of a high potassium reading and said it could come from the way blood was collected. Will you repeat that for me? If I remember correctly, it was caused by the method used in collecting the blood.

Is there an explanation for a high reading to persist? Every food seems to have potassium in it. What is the acceptable potassium level? What underlying conditions cause it to rise? — D.P.

ANSWER: If you’re into looking things up on the Internet, high blood potassium is hyperkalemia. It spawns a number of problems. Heartbeat abnormalities are one of them. It changes the appearance of the EKG. Very high levels stop all heart action. High potassium leads to muscle weakness and even paralysis. It upsets the body’s normal acid-base balance.

The reference you want repeated was on pseudohyperkalemia (false high blood potassium). It’s a release of potassium from blood cells during or shortly after blood is collected in a tube. Clenching the hands into a fist too forcefully or too repeatedly can lead to potassium leak from blood cells. Fist-clenching makes veins stand out so obtaining the specimen is easier and less painful. Cooling of the tube on its way to the lab is another source for false potassium elevation. These are not common occurrences. A second sample solves any confusion arising from a false elevation of potassium.

Potassium is found in many foods. We’re encouraged to get 4,700 mg of it daily. It keeps blood pressure on the low side. Dietary potassium is seldom the cause of persistent blood elevation of it. The kidneys are expert chemists and get rid of any dietary overloads. Conditions associated with a rise in potassium include muscle injury, strenuous exercise, heart failure, overuse of nonsteroidal anti-inflammatory drugs (Aleve, Advil, Motrin, etc.), failing adrenal glands and kidney malfunction. Don’t get involved in tracking the cause of high potassium. That’s something your doctor has to do.

The normal reading for potassium is 3.5 to 5.0 mEq/L. Symptoms don’t appear until the value is 6.

DEAR DR. DONOHUE: My dad died of diverticulitis at age 58. I live in fear of it. Is it inherited? — F.W.

ANSWER: Heredity has little, if anything, to do with diverticulosis or diverticulitis. Diverticulosis is the presence of many tiny pouches protruding from the wall of the colon. Diverticulitis is inflammation of those diverticula. Death from diverticulitis is quite rare.

Diverticulosis is common in North America. One reason is the lack of dietary fiber. Our grains (flour) are refined. The refining process removes fiber from the grains. The best way to prevent diverticulosis is to increase fiber with whole-grain cereals and breads, vegetables and fruits.

The booklet on diverticulosis/itis explains it and how to prevent and treat it. Readers can obtain a copy by writing: Dr. Donohue — No. 502, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I notice that I get migraine headaches when my periods come. Is this just my imagination or is it real? I’ve asked others, and they say they’ve not heard of it happening. — N.D.

ANSWER: Menstrual periods trigger migraine headaches in women who suffer from migraines. That’s a well-known fact.

Apparently, the hormonal changes at the time of periods are responsible.

If the headaches come predictably, you can prevent them by taking migraine medicine a day or two before your periods. That means you have to keep a record of your periods and the number of days between periods so you can dose yourself on the appropriate day.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.