DEAR DR. DONOHUE: I’d greatly appreciate your explanation of vasculitis. Several dictionaries are vague, at best. – J.A.

ANSWER: Vasculitis is inflammation of blood vessels’ walls. The inflammation harms those walls.

More than 22 different illnesses fall into the category of vasculitis. Each has a different name, a different outlook and often a different treatment. If your doctor can give you the specific name of your vasculitis, I can provide more meaningful information.

The vasculitis illnesses are classified on the size of the blood vessels involved – small, medium or large – and on the organs or tissues supplied by the inflamed vessels.

Here are some examples: Temporal arteritis – also called giant cell arteritis – is an inflammation of large arteries. The temporal artery, at the temple on either side of the head, is inflamed. Its inflammation leads to headaches and tenderness over that artery.

Periarteritis nodosa is an inflammation of medium-sized arteries and the arteries involved serve the digestive tract, the skin, nerves and kidneys, so its manifestations are diverse. Weakness, fever, abdominal pain, headaches, high blood pressure and kidney failure are some of its signs and symptoms.

Behind the scenes in many of the vasculitis illnesses is the immune system. Medicines that rein in a misbehaving immune system and calm inflammation are often employed. Prednisone – one of the cortisone drugs – is frequently prescribed. Cyclophosphamide is another medicine turned to for vasculitis.

DEAR DR. DONOHUE: I hope you can help me. I have loud clicks in my left hip when I walk. The hip doesn’t hurt. It’s just the noise that bothers me.

I consulted a bone and joint doctor, who ordered X-rays. Nothing showed up. He said there wasn’t anything he could do. Please help. – L.E.

ANSWER: The hip doesn’t hurt you. The X-ray shows no damage. You can move your hip in all directions. An orthopedic doctor found nothing wrong.

You might not need help. The noise might be only the snapping of a tendon as it passes over the hip bone. There’s not a whole lot to do for that.

DEAR DR. DONOHUE: My husband and I have been sleeping on a waterbed for 30 years. We love it. Now, in our early 60s, should we start thinking about a regular mattress? Or does it make any difference? We find a regular mattress too hot for our backs. I sweat all night when I have to sleep on one. Waiting for your answer. – C.S.

ANSWER: I can’t come up with any reason why you should switch. You’ve been on a waterbed for 30 years and no trouble has developed. There’s no reason to think any trouble will ever develop. Sleep on it for the next 30 or more years.

DEAR DR. DONOHUE: How many enemas are required before a colonoscopy? Should so many be given that the patient is weak and barely able to walk? – L.C.

ANSWER: More people complain about the preparation for a colonoscopy than about the actual procedure. To make the exam valid, the colon has to be free of all fecal material so that the doctor can spot suspicious growths. Polyps are tiny, and undigested food hides them.

Where I live, the prep for a colonoscopy entails taking oral laxatives like X-Prep, GoLYTELY, NuLYTELY, Visicol, MiraLax and many others. For some, the laxative route is as taxing as your experience with enemas. I don’t have a number for the exact number of enemas to be taken. It sounds like you had to take an inordinate number. When your turn comes for a repeat, explain to the doctor that the preparation was very grueling, and maybe some accommodations can be made for you.

DEAR DR. DONOHUE: What tests are needed to diagnose rhabdomyolysis? I’ve been on six different statin drugs for cholesterol for eight years and have had leg pain for the last year and a half. Is a specialist needed to diagnose this syndrome? Is it permanent? – D.T.

ANSWER: You don’t need a specialist to diagnose rhabdomyolysis (RAB-doe-my-OWL-uh-siss). It’s a destruction of muscles. Blood levels of the muscle enzyme creatine kinase – CK – indicate muscle destruction, as do high blood levels of myoglobin, a muscle protein that transports oxygen to different sites within the muscle cell.

Rhabdomyolysis usually isn’t permanent. When muscle breakdown is extreme, the condition can be dangerous and threatens kidney shutdown.

Muscle pain is common. Muscle pain from statin drugs isn’t all that common. Rhabdomyolysis from statin drugs is very rare. Statin drugs are cholesterol-lowering medicines – Mevacor, Zocor, Crestor, Pravachol, Lipitor and Lescol.

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