DEAR DR. DONOHUE: Three years ago I went in for a physical, and the doctor ran all kinds of blood tests. One was very new. It detects inflammation of the artery lining. I had the beginnings of inflammation in the lining of my arteries.

My question is: Is the inflammation of the lining of arteries serious, and is it related to what killed John Ritter? What is the treatment for it? – N.P.

Cholesterol, in spite of all the press it gets, is only one risk factor for the artery clogging that leads to heart attacks and strokes. More than 300 risk factors for it have been proposed. Of those 300, inflammation of artery lining is a recent addition.

Inflammation cells loaded with fat and cholesterol penetrate the artery lining and its wall. That is the beginning of plaque, the gruel of material that can become so large that it fills the artery and blocks blood flow. Another scenario has the fragile plaque buildup rupturing, leaving a raw surface that fills with blood protein and blood platelets. This causes blood flow obstruction and can result in a heart attack or stroke, depending on the artery involved.

Some people are of the opinion that the inflammation is triggered by a germ called chlamydia. So infection might be the main culprit.

C-reactive protein – CRP – is the blood test to which you refer. It’s a test that detects body inflammation, but it does not provide information on the location of the inflammation. It appears to be as reliable a detector of artery trouble as cholesterol is.

John Ritter died of an aortic dissection, a tearing apart of the main body artery, the aorta – not related to this.

Statin drugs – Zocor, Lescol, Pravachol, Mevacor, Lipitor and Crestor – lower CRP, but no one is sure that lowering it is beneficial. It might be, but the facts are not yet in.

DEAR DR. DONOHUE: I am a 57-year-old male who has polycythemia vera. I have a phlebotomy done routinely, and about 1 pint of blood is taken each time. What is the hematocrit? Can you give me more information on it? – T.G.

Polycythemia is a blood condition where there are too many blood cells, especially red blood cells. The bone marrow has gone berserk and produces excessive numbers of blood cells. The result is thick blood that circulates poorly and can cause symptoms that include headache, lightheadedness, ear ringing, night sweats and even things such as strokes. People with it can experience an intolerable itch when they bathe or shower. Fatigue is another prominent symptom. So is bleeding, something you would think would never happen when there is an excess of blood platelets, the small blood cells that promote clotting. The reason why bleeding can occur is that the platelets of polycythemia are often defective.

The “vera” indicates “true” polycythemia, in contrast with polycythemia that occurs when people live at high altitudes, for example. At heights, oxygen-poor air stimulates the bone marrow to increase the production of blood cells.

Hematocrit is an indirect measure of red blood cell numbers. It’s a simple test that determines how much of the blood volume is actually red blood cells. The upper limit for men is 52 percent, and for women, 42 percent.

Treatment sounds medieval. It’s nothing more than removing blood – phlebotomy (fleh-BOT-uh-me).

The goal is to lower a man’s hematocrit to less than 45 and a woman’s to less than 42.

If blood removal is not completely effective, the medicine hydroxyurea is employed.

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.

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