DEAR DR. DONOHUE: I am 82 and in good health for my age, but recently I have been experiencing fatigue and shortness of breath when I do anything of a physical nature, like walking too fast or too far. I consulted a physician, and a blood test showed a high white blood cell count and a thyroid condition for which I was given thyroid hormone.

I have been a nonsmoker for more than 50 years. My heart was checked and said to be OK, and there was no indication of a lung problem. My blood pressure is normal. If you’d address my condition, I would appreciate it. – J.H.

ANSWER: Your symptoms could indicate a heart that isn’t pumping as forcefully as it should. Exercise intolerance, breathlessness and fatigue are three cardinal signs of heart failure.

So this is something to be kept in mind even though your heart was declared healthy.

Another important place to look is the lungs. Aging causes a drop in the amount of oxygen that gets from the air in your lungs to your blood. If the blood oxygen content falls below a critical level, people fatigue easily and are hungry for air.

A chest X-ray or listening to the chest with a stethoscope can’t diagnose this. Blood tests for oxygen and lung function tests are needed. This might be a place where some more attention can be paid.

Anemias cause these symptoms. You had a blood count. Apparently you have an ample supply of red blood cells or you would have been informed that you’re anemic. I don’t know what to make of the high white blood cell count. How high was it?

A low level of thyroid hormone makes people tire quickly and sometimes makes them short of breath. People with too little thyroid hormone have dry skin and feel cold. They’re often constipated. Do you have any of these symptoms?

Your tests show you lacked thyroid hormone, so this might be the answer for you. It takes four to six weeks before replacement hormone improves symptoms. It might just be a matter of time before you’re feeling more energetic.

Congestive heart failure is a common condition whose understanding is often poor. The booklet on that topic can clear the issue for people.

To order a copy, write to: Dr. Donohue – No. 103, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6.75 Can. with the recipient’s printed name and address.

Please allow four weeks for delivery.

DEAR DR. DONOHUE: I do not recall if I ever had chickenpox. I think I did. My parents have passed on, and my early-childhood medical records are no longer available.

I will be 60 years old next year. I would like to know if it is OK to get the shingles vaccine whether or not one has had the chickenpox. – A.K.

ANSWER: Readers who are puzzled by this question need an explanation. Once infected with the chickenpox virus, a person retains the virus in the body until death.

Later in life, the virus emerges from its sanctuary inside nerve cells, travels down nerve roots to the skin and causes the skin outbreak and pain called shingles.

Most older people, even if they cannot remember having had chickenpox, have been infected with the chickenpox virus. Infection with the virus doesn’t always bring the overt signs of chickenpox. Or the infection can be so mild that it was never recognized as chickenpox.

The short answer to your question is that you can get the vaccine and you should.

DEAR DR. DONOHUE: I am 71 years old. When I was 5 or 6, I had a smallpox vaccination. It did not take. I had another one a year later, and it did not take.

The doctor told my mother I was immune. My current doctor wants me to take the shingles shot. Do I need to take it, or am I immune? – N.T.

ANSWER: You’re not immune to shingles. You’re not immune to other infectious diseases.

The smallpox vaccination might not have taken because it wasn’t properly given or because your body simply doesn’t react to that vaccine. You should have all the immunizations that older people need. You need the shingles vaccine.

As an aside, did you know that smallpox has been eradicated from the Earth? It’s one of medicine’s biggest accomplishments.

DEAR DR. DONOHUE: I would like your opinion on my granddaughter, a 15-year-old girl, a dancer, who has not yet had a period. – W.G.

ANSWER: The average age for a first period is 12.3. There’s a wide variation to that average. If a girl hasn’t menstruated by 16, then an investigation into what’s causing the delay is begun. Your granddaughter has some time before that investigation in undertaken.

Your granddaughter is a dancer. Is she quite thin? Female dancers and gymnasts prize being on the lean side. A girl has to have a certain amount of body fat to have periods.

If your granddaughter is strictly watching her calories, she would be wise to liberalize her diet a bit. A calorie-deficient diet is often at the bottom of delayed menstruation.

If she’s not deliberately keeping herself thin, then she still has time to menstruate and be considered in the normal range of things. If, at 16, it turns out that she’s not producing enough estrogen to have periods, that’s something that has to be corrected. Estrogen production is needed not only for periods but also for strong bones.

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