DEAR DR. DONOHUE: My doctor wanted me to have a stress test. After a few minutes of the test, the doctor stopped it and sent me to a cardiologist. He told me upfront that I had blockage in my heart arteries but, to be sure, he wanted a nuclear stress test. That was more abnormal than the first test, so he went ahead with a heart cath. Nothing wrong was seen on the heart cath. How could I have had a false positive stress test? Now I am afraid to exercise. I am a 60-year-old woman. – G.M.

ANSWER: It’s a kick in the head to learn that such an involved test as a stress test can yield erroneous results, but no medical test is 100 percent reliable.

A basic EKG – one of the more simple heart-illness detection tests – identifies heart disease only 50 percent of the time – not exactly a monument of dependability.

A stress test – a continuous EKG taken while a person is on a treadmill – gives better information. Every three minutes the treadmill speeds up and the incline increases. The increasing pace of exercise “stresses” the heart and determines if the heart gets enough blood when it must pump harder. A stress EKG detects heart disease accurately close to 70 percent (true positive) of the time, a definite improvement over a resting EKG. But it misdiagnoses heart disease 20 percent (false positive) of the time, showing changes that look like a heart problem when there is no heart problem. This is especially the case for women.

A nuclear stress test – a stress test done along with the injection of a radioactive tracer to take pictures of the heart and its arteries – can reliably detect true heart disease 85 percent of the time.

A cardiac cath – injecting dye directly into heart arteries – is the most trustworthy test available. You can believe its results, and you can exercise if your doctor says so. The other tests were falsely positive.

The coronary (heart) artery disease booklet provides details on the detection and treatment of this most common illness. Readers can obtain a copy by writing: Dr. Donohue – No. 101, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6.75 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: A couple of times in the past, you have written about Paget’s bone disease. I had Paget’s breast disease. It was cancer. Are these two illnesses related? – A.G.

ANSWER: No, they are completely different. Dr. James Paget was a 19th-century British surgeon whose name is attached to both because he was the first to describe them.

Paget’s breast disease is a rare breast cancer. It starts as a red, scaly eruption of the nipple. The involved area often itches. Sometimes the process is mistaken as eczema. The cancer arises in milk ducts, and fluid with cancer cells leaks from the nipple. Microscopic inspection of the fluid demonstrates cancer cells.

Paget’s bone disease is an imbalance between the normal daily breakdown and buildup of bone. It results in sections of weak and misshapen bone.

DEAR DR. DONOHUE: Shortly before the polio vaccine became available, I caught polio. As a child, it was tough on me, but with therapy I managed to do well. I walk with a barely detectable limp. I have been quite active during my life and have played and still play many sports.

The one question that has bugged me all these years is, How did I catch it? – J.Z.

ANSWER: Polio virus replicates in the intestinal tract. Virus is passed in the feces and often gets onto a person’s hands. That person, with virus-coated hands, can pass the virus to others.

Less frequently, when the virus is temporarily in the throat, it can be expelled with a cough or a sneeze and passed along in droplets. This method of transmission is uncommon.

The eradication of polio from the world is a goal of the World Health Organization. The completion of that goal is not too far off.

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

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