DEAR DR. DONOHUE: Would you tell me your source for the new blood pressure guidelines? I have high blood pressure and have done quite a bit of research on it. I find that sources vary as to what is considered normal and abnormal pressure. When I visit my doctor, the nurse walks me down a long hallway and takes my pressure immediately. I know her reading is not the true reading. The doctor accepts it and changes my medicine at every visit. How should blood pressure be taken? – J.B.

ANSWER: Most doctors accept the blood pressure guidelines developed by a group of experts working under the direction of the National Institutes of Health. The group meets every few years to revise the norms. The last meeting took place in 2003, and the norms are published in a statement titled the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure. The title is shortened to JNC 7 – the seventh report of the Joint National Committee. You can find it at www.nhlbi.nih.gov/guidelines/hypertension.

The new classification puts normal blood pressure below 120/80. Blood pressures between 120/80 and 139/89 are now called prehypertension. Pressures from 140-159/90-99 are stage 1 hypertension, and stage 2 is any reading of 160/100 or higher.

The goal of treatment is to reduce blood pressure to less than 140/90. If a person happens to have another illness such as diabetes, the goal is for an even lower blood pressure – 130/84.

Valid blood pressure readings are obtained only if the rules for taking blood pressure are followed to the letter. A person should be seated quietly for five minutes before pressure is taken, and that person should not have had any caffeine or nicotine for 30 minutes prior to pressure taking. The arm with the blood pressure cuff should be supported and at heart level.

Why not get your own blood pressure machine and take a record of your home readings to your doctor?

DEAR DR. DONOHUE: I am a 22-year-old female and have developed a strange condition. When I eat ice cream, I get the runs and stomach cramps. Is this an allergy? I used to eat it without any trouble. – R.J.

ANSWER: It’s not likely an allergy. It’s more likely an intolerance to milk sugar – lactose. The digestive tract contains an enzyme, lactase, that breaks down milk sugar for absorption. Without enough of the enzyme, undigested milk sugar draws water into the digestive tract, which leads to cramps and diarrhea. Furthermore, intestinal bacteria dine on the milk sugar and change it into fatty acids that increase the laxative effect.

You’re lucky if ice cream is the only dairy product that causes you trouble. You can search for ice cream (or other dairy products, including milk) that has been treated with the enzyme so its milk sugar comes predigested.

The other way around the problem is to avoid dairy products. If you take this route, be sure to add a calcium supplement to your diet. Dairy products are the greatest natural source for calcium. Without enough of it, the stage is set for osteoporosis at a later date.

DEAR DR. DONOHUE: My mother suffered from Bright’s disease and eventually died from it. Is it hereditary? She died when she was 43, just before World War II broke out. I am 77. Would it have shown up by now if I had inherited it? – D.V.

ANSWER: Dr. Richard Bright, who died in 1858, identified body swelling and urinary protein as signs of kidney disease. In his day and for many decades after, most kidney disease was called Bright’s disease.

Since then, sophisticated tests distinguish the vast array of kidney diseases, so the name “Bright’s disease” has faded into obsolescence.

If your mother had passed an inherited kidney disease to you, you would have had signs of it by now.

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.