QUESTION: I have polyarteritis nodosa. What causes it? How does it affect the body? I know there is no cure, but I am taking prednisone and get frequent sed rate tests. - D.M.

ANSWER: Polyarteritis means inflammation of many arteries. The inflamed arteries may include those serving many organs, including the skin, kidneys, heart, liver and digestive tract. The symptoms, of course, reflect just which organs are involved.Symptoms most often reported are fever, weight loss, muscle pain and abdominal pain. I'm afraid I cannot tell you the cause of the inflammation. In the 124 years since polyarteritis was first described, the cause has remained a mystery. However, evidence now points to something that's gone a bit haywire in the body's immunity system. It has been misled into attacking the person's artery tissue.

Cortisone drugs, like your prednisone, are mainstays in controlling the inflammation. If they are not working, the doctor may consider a combination of drugs that suppresses the immune system sufficiently to halt the immunity attack I mentioned. They along with the cortisone drugs usually do the trick.

The sed rate test you mention is, in fact, a test to determine how well inflammation is being controlled. The "nodosa" part of your ailment means only that small bulges are seen microscopically when an inflamed artery is biopsied.

QUESTION: I have bronchiectasis. Can you discuss? - L.L.

ANSWER: Bronchiectasis is a permanent dilation of one or more of the breathing tubes ("ectasia" means dilation or expansion). The "bronchi" part of the term indicates the lung tubes whose walls are weakened from the ravages of the inflammation.

Often the condition reflects an old lung infection. In the past, TB was a common cause of bronchiectasis. So too was whooping cough before the advent of vaccination for that illness. Today, bronchiectasis is somewhat rare, except perhaps as a complication of pneumonia. And TB is making an unwelcomed comeback on the medical scene, of course.

One effect of bronchiectasis is a buildup of mucus, pus and cell debris on the breathing tube walls. This may cause chronic pus-like phlegm, chronic cough and repeated lung infection.

You cannot reverse the damage, but you can control things. You can learn drainage techniques from a respiratory therapist. You must get antibiotic treatment for lung infection flare-ups and be vaccinated against pneumococcal pneumonia, the most common kind today. In very severe cases, diseased tubes are removed surgically.

Some forms of bronchiectasis are inherited, but that's rare.

1990 North America Syndicate Inc.