DEAR DR. DONOHUE: Do people ever completely get over mono? My daughter, a high-school junior, came down with it in December. She has gone back to school, but she’s not her same self. I am beginning to wonder if she will ever fully recover. What do you think? – A.A.

If your daughter is like most people, she will get over mono – infectious mononucleosis – completely.

The Epstein-Barr virus causes mono. In the very young, mono infections produce mild signs and symptoms unlike the signs of symptoms that occur during the teens and early 20s. In those years, mono brings a sore throat, an elevated temperature and swollen lymph nodes, particularly neck nodes. The illness saps the body of energy. The mono virus infects the liver, but in most instances, the only sign of liver infection is an abnormal liver blood test.

Saliva spreads the virus, and an actively infected person usually isn’t the one who transmits it. The virus is found in saliva for a long time after all mono signs and symptoms have disappeared. It’s the walking well who disseminate the illness.

As far as duration of illness, most are over and done with it in three or four weeks. In fact, the mono sore throat is usually gone in five to 10 days, and fever leaves in a week or two.

Fatigue, however, is another story. It can remain for some time. Quite often, during convalescence a person will feel super one day but draggy the next. Lymph nodes take a fairly long time to return to normal. Your daughter might be in this phase right now. She shouldn’t push herself to perform all the activities she used to take part in until she feels up to it.

DEAR DR. DONOHUE: I was diagnosed with essential thrombocytosis nine months ago and have since tried to find out all I can about it. The condition was diagnosed because my platelet count was high and I had the gene marker JAK2V617F. I was put on hydroxyurea.

What is this gene mutation? When did it happen? Have I always had it? Does it affect my prognosis? Is this condition passed on to my children and grandchildren? Not understanding genes, I feel woefully ignorant. – B.V.

Essential thrombocytosis is an increased number of blood platelets, the blood cells involved in forming clots. “Thrombocyte” is another name for platelet. The “essential” in the name indicates that the basic cause of this condition remains a puzzle.

In the bone marrow – the place for the production of all blood cells – a platelet parent cell starts reproducing these clot-forming cells in great abundance. The result can be unwanted clots or, paradoxically, bleeding. Hydroxyurea reduces the number of platelets.

The gene change occurred in the parent platelet cell long after you were born, probably in the past few years. Genes are always mutating. Sometimes the body annihilates the mutant. Sometimes the cell with the new gene propagates and leads to a disorder like yours or, in some, to cancer. Not all people with this illness have the mutant gene. Therefore, it is not the sole cause of this disorder, but it might have a hand in your coming down with it. You did not pass the gene to your children. It doesn’t alter your prognosis. It serves as an identification of this illness.

Essential thrombocytosis is a rare illness. There is a variant of it that is passed in families. That’s an even rarer illness. You do not have that kind of thrombocytosis.

DEAR DR. DONOHUE: I am 63. In checking my blood pressure, the readings are higher in my left arm. Why? Which reading should I go by? – J.H.

Take the higher reading as your blood pressure. There should not be more than a 10-point difference in blood pressure in the two arms. If there is, it can indicate a narrowing of the artery in the arm with the higher blood pressure, or it can be nothing more than a quirk.

DEAR DR. DONOHUE: I work hard cleaning other people’s homes as well as my own. I also raise vegetables in a large garden. I am tired at night. Am I supposed to exercise on top of all this? My weight is fine, and I feel fine. – R.G.

Not many people perform as much physical labor as you do. You’re getting the required amount of exercise, but let me explain a few points worth emphasizing.

Aerobic exercise is the kind that keeps the heart and blood vessels healthy. Large muscles – the arms or legs – have to work continuously for at least 20 minutes to qualify an exercise as aerobic. Furthermore, the heart has to beat at a certain rate during the exercise. A very rough guide in determining what the heart rate ought to be is to subtract your age from 220 to obtain your maximum heart rate. If you’re 40, your maximum heart rate is 180 beats a minute. To reach the aerobic zone, the heart must beat 60 percent to 80 percent of its maximum rate. For a 40-year-old that would be a heart rate of 108 to 144 beats a minute. It is not hard while doing housework to reach a heart rate of 108 beats, but it would be hard to reach 144 beats a minute. So long as you meet the minimum, you’re getting aerobic exercise.

You can forget all this and make a subjective judgment about the intensity of your work. If you can honestly say it is moderately hard, then you’ve reached the aerobic threshold.

As for calorie burning, scrubbing floors is on the same level as playing singles tennis. Housecleaning is about equal to a brisk walk. Digging a garden – your hobby – is the equivalent of cross-country skiing, one of the most demanding of all exercises.

A point about strength training also needs to be made. The same amount of work, day in and day out, does not make muscles stronger or larger. The load on muscles must constantly increase. If your goal is not bulging muscles, then you can forget this aspect of conditioning.

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

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