DEAR DR. DONOHUE: My husband just returned from the doctor with a possible diagnosis of polycythemia. Neither he nor I know anything about this. Would you tell us its significance? Is it a form of cancer? I suspect it might be. – W.B.

ANSWER: Polycythemia (POWL-ee-sigh-THEME-ee-uh) isn’t cancer. It comes from a bone marrow that makes too many blood cells – red, white and platelets. Most attention is directed to the red blood cells. What pushed the marrow into this overproduction mode is something that has yet to be explained.

I’ll bet the doctor discovered it not from symptoms your husband might have, but from blood work that showed a high red blood cell count.

Too many red blood cells can cause as much trouble as too few. People with too many red blood cells are often dizzy and have ringing of the ears or hear other noises. They frequently complain of headaches. Blood pressure might rise. Itching is another common symptom. The blood – crowded with red blood cells – thickens, and heart attacks are a danger. Blood uric acid levels can rise and bring on a gout attack.

The numbers of red blood cells can increase for reasons other than polycythemia. Cigarette smokers often have a higher-than-normal count. Your husband’s doctor gave your husband a tentative diagnosis while he investigates the other causes of his increased red blood cells.

Treatment is straightforward – removal of blood. Blood is taken until the count approaches normal. When it has, removal is less frequent, maybe four times a year.

If blood removal doesn’t keep the red blood cell count at normal levels, the medicine hydroxyurea often can.

DEAR DR. DONOHUE: I had taken a water pill every day to control my blood pressure. It worked, but it also caused a drop in my potassium. I didn’t have any symptoms, but my doctor gave me a potassium supplement to take. That didn’t raise my blood potassium level, so he took me off the water pill. My potassium didn’t come back to normal. Now I have been on potassium without any water pill for two months, and my potassium level still runs low. What might be going on? – L.C.

ANSWER: Yours is an unusual situation. Almost 100 percent of the time, diuretic-caused low blood potassium comes back when the diuretic is stopped and potassium is given. When it stays low in these circumstances, you have to start looking for seldom-seen causes.

Among those causes is an adrenal gland tumor that makes too much of the hormone aldosterone. It’s involved in raising blood pressure and regulating potassium. Cushing’s disease, another adrenal gland problem, depletes potassium. So can a narrow kidney artery.

After two months of having a low potassium level that doesn’t respond to treatment, it’s time someone started looking for rare causes. Something funny is going on. You should consult a nephrologist (a kidney specialist) or an endocrinologist, a doctor whose specialty includes the adrenal gland.

DEAR DR. DONOHUE: I take my temperature every day. I take it first thing in the morning after I wake up. It’s around 97.5 F. Isn’t this abnormally low? I don’t have much energy, and I wonder if it might be related to this low temperature that I run. Do you think so? – P.G.

ANSWER: Body temperature doesn’t stay at 98.6 (37 C) throughout the day and night. It fluctuates depending on the time of day and what we’re doing. It hits a low point in early morning and a high point in early evening.

I can’t tell you what’s causing your lack of energy, but it’s not related to your temperature. You have to look for a different explanation.

Why are you taking your temperature every day? It’s not necessary, and it’s worrying you without being a cause for worry.

DEAR DR. DONOHUE: I get unsightly bruises, even from bumps that are so minor I hardly notice them. They’re mostly on my arms. My doctor said it was due to old age. I refuse to accept that. I am 79. Isn’t there another explanation? – P.G.

ANSWER: The age explanation is a reasonable one. Aging thins skin, and it undermines the support of blood vessels. They aren’t as protected as they were in youth. Slight trauma breaks delicate vessels. The blood leaks into the skin, and a bruise is born.

The only solution to the problem is to wear clothes that protect the arms. That’s not a genius statement on my part, and it’s often hard to do, but I don’t know any other satisfactory answer.

If you’re bleeding from any other place – frequent nosebleeds, for example – then thoughts turn to the possibility of clotting disorders. One of those disorders is a deficit of blood platelets, the tiny blood cells that form clots to plug broken blood vessels. Laboratory tests reveal platelet status and the status of other clotting factors.

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