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Q: As a physical therapist, I have been trained to take blood pressures. Because I am borderline hypertensive, I am now doing it on myself at home. But when I listen for the systolic sound, I hear a faint thump about 20 points above the main thump.

This obviously makes a big difference between a high or average systolic pressure. I've spoken to doctors and nurses but get different answers.

-- J.M., Lady Lake, Fla.
A: I'm glad to hear you are monitoring your own blood pressure. The readings you get at home reflect what's happening in your daily life and you'll be able to detect changes earlier than if you had to rely on someone else.

I'm sorry to hear, though, that you have the problem you present. It does point to the fact that taking blood pressure readings with the standard sphygmomanometer is not an exact science. It's a good idea to follow some simple rules when taking your blood pressure:

-- Relax for at least 10 minutes first.

-- Take readings in a quiet setting.

-- Take readings in both arms.

-- Occasionally check the pressure in both legs as well.

-- Repeat readings that have changed.

-- Note abnormal sounds.

The sounds heard through a blood pressure cuff are caused by the change in flow of blood through the arteries that are blocked off by the blood pressure cuff. At some point -- as you release the pressure in the cuff -- the blood will just start to flow. A sound begins and marks the level of the systolic pressure.

And as the pressure in the cuff gets less and less, the artery will open fully and the sound will stop. This marks the level of the diastolic pressure. At least, that's the theory.

For some people, sounds don't stop when the diastolic pressure is reached, but rather they change character. And some people, like you, hear a sound before the systolic pressure is reached.

It's possible you are hearing the sounds caused by more than one artery in your arm. For example, if the pressure is not applied completely throughout your arm, a smaller artery may be opening up sooner, causing the faint thump.

It is possible, however, that you are hearing the transmission of a sound from as far up the bloodstream as your heart. If you are worried about this, I suggest that you talk with your health professionals and do the following: (1) See if the first thump is heard in all arms and legs; and (2) have someone simultaneously listen over other parts of your body, including your heart, to see if they can hear it, too.

If this doesn't help resolve your case, you may be able to persuade your doctor to use more sophisticated listening devices to try to pinpoint the source. I've never seen studies to indicate what to expect in your case, but I suspect you don't have a medical problem as the cause. I also suspect you will be better off using the louder, second sound as your reference point with regard to high blood pressure.

Update on soy protein: The Food and Drug Administration has concluded that foods containing protein from the soybean as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease.

The amino acid content in soy protein is different from animal and most other vegetable proteins and appears to alter the synthesis and metabolism of cholesterol in the liver.

Foods containing soy protein include soymilk, tofu, meat substitutes and baked goods made with soy flour. And, if the FDA's proposal to allow foods containing soy to carry this health claim goes through as expected, we'll be seeing a lot more soy in processed foods as well.

Dr. Allen Douma welcomes questions from readers. Although he cannot respond to each one individually, he will answer those of general interest in his column. Write to Dr. Douma in care of Tribune Media Services, 435 N. Michigan Ave., Suite 1400, Chicago, Ill. 60611. His e-mail address is

This column is for informational and educational purposes only. It is not intended to provide medical advice or take the place of consultation with a doctor or other health-care provider.

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