DEAR DR. DONOHUE: Please say something about vasculitis. My sister has it, but she’s so vague about it that I really don’t understand what she has or how it affects her life. Does it run in families? What treats it? Does anything prevent it? – R.K.

ANSWER: Vasculitis is blood-vessel inflammation. It’s a word that encompasses at least 13 different diseases, each with its own symptoms, many with their own distinctive treatment and all with different significance.

Vasculitis illnesses, however, do share two common features. One is that the inflamed blood vessels make it difficult to impossible for blood to flow through them. Organs or tissues supplied by those vessels suffer. The other common feature is that antibodies, produced by the immune system, are found in almost all the vasculitis varieties.

If your sister can provide you with the name of her vasculitis, I can make the information more pertinent to her.

Let me give you a brief rundown of one kind of vasculitis – polyarteritis (that’s “arteritis” for arteries and not “arthritis” for joints) nodosa. Arteries going to skin, heart, digestive tract, kidneys, joints and nerves are targets of inflammation. Kidney involvement is quite common and leads to high blood pressure and often kidney failure. Joints can become painful. Inflamed digestive tract arteries cause stomach pain, bleeding and possible death of sections of the intestines. Affected heart arteries might bring on heart failure.

Prednisone, one of the most important anti-inflammation drugs available, is standard treatment, and it’s often combined with cyclophosphamide, a medicine that can restore sanity to the immune system that’s producing harmful antibodies.

There’s a genetic predisposition to this illness, but that’s far from saying it runs in families. Prevention isn’t possible.

DEAR DR. DONOHUE: In my younger days, I was a very sexually liberated woman. I took birth control pills and believed I could have sex whenever I wanted and with whomever I met. I must not have realized that the pills don’t protect against infections. I had a case of pelvic inflammatory disease that landed me in the hospital, where I had to have intravenous antibiotics. I have changed my ways. Could PID have made me infertile? I want to settle down with one man and have a family. – S.O.

ANSWER: Pelvic inflammatory disease is a serious and painful infection that can be acquired through sexual relations, but that’s not the only way it’s caught. More than a million Canadian and American women are treated for it yearly.

The pelvis is the part of the body just beneath the abdomen. The pelvic bones are its boundaries. They make a deep bowl that contains the uterus, the ovaries and the bladder. You can feel those bones by putting your hands on your waist at or just below the beltline.

Infection of the pelvis and its organs often make an infected woman double over in pain. She has a high fever and frequently a vaginal discharge.

If the pain isn’t too terrible, the infection can be treated on an outpatient basis with antibiotics. In more serious infections, hospitalization is necessary with intravenous antibiotics.

One episode of pelvic inflammatory disease can make a woman infertile, but it doesn’t ordinarily do so. Three episodes of PID, however, increase the chances of infertility to 50 percent.

DEAR DR. DONOHUE: I have a white blood cell count of 4,000. I know the normal is 10,000. My doctor is indifferent to this. What should I do? – M.A.

ANSWER: The normal lower limit for white blood cells is 4,500. You are not far off the mark. White blood cells are infection fighters. You haven’t suffered any infections, have you? If you haven’t, you don’t need to do a thing. Many people have a count similar to yours and don’t run into any trouble.

DEAR DR. DONOHUE: A 29-year-old family member has been diagnosed with ITP (low platelets) and has been treated with three medicines. Nothing holds her count up for very long. Her doctors say the next step is to remove the spleen. What are your thoughts on this? What are the repercussions of not having a spleen? – S.V.

ANSWER: ITP – idiopathic thrombocytopenic purpura – is a deficit of platelets, also known as thrombocytes. “Penic” indicates deficiency, and “purpura” are the bruises that appear when there are too few platelets. Platelets are the smallest blood cells, the ones intimately involved in forming clots.

In children, ITP often follows a viral infection like a cold, and most children’s platelet numbers are restored to normal in a relatively brief time. In adults, ITP follows a more chronic course. Usually it happens to women between the ages of 20 and 40, and most often a cause isn’t found.

The spleen has a ravenous appetite for platelets that have been coated with antibodies, as they are in ITP. Medicines – prednisone is often the first one chosen – can often dampen the antibody-coating action and restore platelet numbers. When medicines fail to achieve a sustained increase in their numbers, then removing the spleen is a logical step.

Thousands of people live healthy, long lives without their spleens. Many professional athletes have had to have a ruptured spleen removed. Contact sports can split the spleen, which has to be promptly taken out to prevent life-threatening hemorrhage. These athletes continue to play their sports. Without a spleen, people are at an increased risk for certain infections. The chief such infection is one with the pneumococcus germ, a germ that causes pneumonia, meningitis and blood poisoning. There is an effective vaccine for prevention of pneumococcal infections. Your relative will be given that vaccine and other vaccines that confer immunity against the common infections spleenless people can fall victim to.

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