Medical Tests

Why would a doctor order an ultrasound of the carotid artery?

DEAR DOCTOR K: My father's doctor wants him to have an ultrasound of his carotid artery. What is the carotid artery? What will the doctor be looking for?

DEAR READER: The carotid arteries carry oxygen- and nutrient-rich blood from the heart to the brain. These crucial arteries can become narrowed by the cholesterol-filled plaques of atherosclerosis. Blood clots can form from the plaques, then break off and travel to the brain. There, they can lodge in small arteries, interrupting the vital flow of blood to brain cells.

Will studies of our genes change medicine and improve our lives?

In yesterday's column, a reader asked whether she should be tested for genes linked to Alzheimer's disease. Today, I thought I'd give you my view on the larger question: Will studies of our genes change the practice of medicine and improve our lives?

My answer: During my career, progress in human genetics has been greater than virtually anyone imagined. However, human genetics also has turned out to be much more complicated than people imagined. As a result, we have not moved as rapidly as we had hoped in changing medical practice.

Why do I need a HbA1c test every few months for my Type 2 diabetes?

DEAR DOCTOR K: I have Type 2 diabetes, and I check my blood sugar levels every day. Why do I need to have my HbA1c levels tested every few months?

DEAR READER: Diabetes is marked by high levels of glucose (sugar) in the blood and urine. Without adequate treatment, diabetes can cause serious long-term complications. The key to preventing them is to control blood sugar -- to keep it close to the normal level.

Can you tell me what the different breast biopsy techniques involve?

DEAR DOCTOR K: My doctor saw something suspicious on my mammogram and wants to do a breast biopsy. I understand there are several biopsy techniques. Can you tell me what they involve?

DEAR READER: The invention of mammograms (X-rays of the breast) has saved many lives. Mammograms can spot a small, early breast cancer, and help doctors cure it.

Why is it complicated to test testosterone levels?

DEAR DOCTOR K: I've been having symptoms that may be caused by low testosterone. I figured it would be easy to test my testosterone levels, but my doctor says it's complicated. Why?

DEAR READER: Testosterone is one of the main male hormones. Blood levels of this hormone start to sag in early adulthood, and then creep lower. In some men, the levels become low enough to cause symptoms. The classic symptoms of low testosterone ("low T") are low sex drive, erectile dysfunction, poor muscle tone, poor concentration and memory, and low energy.

Why does my doctor want me to do a food challenge when my blood test showed negative for a shellfish allergy?

DEAR DOCTOR K: Last month I broke out in hives after eating oysters. I had a blood test, which came back negative for a shellfish allergy. Why does my doctor still want me to do a food challenge?

DEAR READER: Allergic reactions occur when your body's immune system overreacts against a harmless substance -- in your case, possibly, shellfish. Food allergies can cause a variety of symptoms that range from mild to life-threatening.

Could you explain what biofeedback is?

DEAR DOCTOR K: You've mentioned biofeedback as a treatment option for several conditions, but I still don't understand what it is. Could you explain?

DEAR READER: Biofeedback is a technique that helps you monitor and control your body's responses. By learning to control certain functions, you can improve your medical condition, relieve chronic pain, reduce stress, or improve your physical or mental performance.

Does having dense breast tissue increase my risk of breast cancer?

DEAR DOCTOR K: After my last mammogram, the doctor told me I have dense breasts. Does this increase my risk of breast cancer?

DEAR READER: A woman's breast contains different types of tissue, including fat. Women with dense breasts have relatively less fat in their breasts. Specifically, if more than 50 percent of your breasts is made up of other breast tissue (as opposed to fat), then by definition you are said to have "dense breasts." It's not uncommon: About 40 percent of women have dense breasts.

What happens during a PET scan?

DEAR DOCTOR K: I'm in treatment for colorectal cancer. My doctor has scheduled a PET scan to see how well my treatment is working. What will happen during this test?

DEAR READER: A positron emission tomography, or PET, scan is an imaging technique. Unlike most imaging techniques, a PET scan primarily shows how different parts of the inside of the body are working, rather than just how they are shaped.

What does colonoscopy preparation involve?

DEAR DOCTOR K: I'm scheduled to have my first colonoscopy. My friends tell me the preparation is worse than the procedure. What am I in for?

DEAR READER: From my long experience as a doctor -- and as a patient -- I think your friends have it right. The large intestine (colon) is a long tube through which digested material passes. In a colonoscopy, a flexible tube with a light and camera at the end is placed inside the colon. What the doctor is looking for are abnormalities in the circular inner wall of the colon, including tumors, bleeding and inflammation.