DEAR DR. DONOHUE: I have Klinefelter’s syndrome. I have information that unless you take testosterone before you hit 30, you’ll never make it past 30. I am 34 and am the oldest person living with this syndrome. – D.N.

ANSWER: Chromosomes are long strands of genes. Each of us has 46. Half come from the mother and half from the father. Two of those chromosomes determine a person’s sex. A woman has a pair of XX chromosomes; a man has XY sex chromosomes.

In Klinefelter’s syndrome, the baby is born with three sex chromosomes: XXY. (There are variations on this combination.) The infant looks like and is raised as a boy.

Often, overt signs of the syndrome aren’t recognized until puberty, and sometimes they are never recognized. They can be quite subtle. Many Klinefelter’s children have difficulty learning. They often are not as coordinated as their peers. At puberty, the testes fail to grow. Most are infertile. Facial and chest hair is scanty. These boys are tall but have poor muscle development. The breasts may enlarge.

When the syndrome is recognized early, the male hormone testosterone is started around age 12 and promotes typical male features. It can even be given much later if there is a delay in recognizing the syndrome.

Klinefelter’s syndrome does not cause death at an early age. That is a piece of misinformation someone has fed you.

You can obtain valuable information on this condition by connecting with the Klinefelter Syndrome and Associates Web site, at www.genetic.org.

DEAR DR. DONOHUE: Under what circumstances is a pacemaker installed to regulate the heart? – J.Y.

ANSWER: The heart’s pacemaker is a tiny island of specialized cells in the upper right heart chamber that generates electrical blips. The electric current is conducted to the lower heart chambers – the ventricles, the pumping chambers of the heart. When it arrives there, they contract and empty the heart of blood. Doctors install a pacemaker when the heart’s natural pacemaker fails or when there is damage done to the conducting cables leading to the lower ventricles and no electric signals reach them.

Pacemakers are also used to regulate some irregular heart rhythms.

Today, a new use for pacemakers is in congestive heart failure. If the two ventricles contract out of sync, a pacemaker can put them back in time with each other. This doesn’t apply to all people with heart failure.

The heartbeat booklet doesn’t describe pacemakers, but it does give an overview of heartbeat irregularities, some of which need a pacemaker. Readers can obtain a copy by writing: Dr. Donohue – No. 107, 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: Can people who lead active lives get bedsores? I am 81. I do sit while reading or working on my hobby, but never for more than two hours at a time. I work in my garden and attend an exercise class. On two occasions, I have had what my doctor called bedsores at the base of my spine. – G.G.

ANSWER: It’s most unusual for bedsores to occur in someone as active as you. Bedsores are really pressure sores. When a person lies in bed or sits in a chair without changing position frequently, an unyielding mattress compresses the skin between itself and underlying bone. Blood supply to the skin is cut off. The skin dies, and a bedsore is created. The base of the spine is a common site for this to happen.

Friction from sliding down in bed and dampness also contribute to the formation of bedsores.

In hospitals and nursing homes, immobile patients are turned every two hours or more frequently to prevent such sores.

I suppose it’s possible that you might be extremely susceptible to them, but I am scratching my head to come up with a reasonable explanation. I cannot.

If you get another, why not get a second opinion?

DEAR DR. DONOHUE: I have been doing a lot of outdoor work. I rest my elbow on the ground. Now I have a large, fluid-filled sac over my elbow. It is not particularly painful, and I have stopped the activity.

The swelling has stayed the same size, about that of a pingpong ball, for at least a week.

Will it go away by itself? Is it a bursa? – J.L.

ANSWER: It is a bursa filled with fluid. Constant irritation is the cause. Rest, heat and anti-inflammatory medicines like ibuprofen, if you can take them, can help it shrink more quickly.

If it hasn’t gone away in another week, do see a doctor. There are other things that look like olecranon bursitis – the official name of this condition. Long-distance diagnoses need an up-close and personal examination for confirmation.

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.