What can I take to ease my hot flashes?

DEAR DOCTOR K: I have terrible hot flashes. My doctor no longer recommends hormone replacement therapy because he says it has heart risks. Is there anything else I can take?

DEAR READER: Hot flashes are a common symptom of menopause. They probably result from changing hormone levels. My patients describe them as a sudden, intensely uncomfortable onslaught of heat. They are often accompanied by a rapid heartbeat, headache, nausea or dizziness.

What is immunotherapy?

DEAR DOCTOR K: I've heard the term "immunotherapy" used by people who are discussing treatments for cancer and arthritis. What is immunotherapy?

DEAR READER: Immunotherapy refers to treatments that work by enhancing or suppressing the body's own immune system. In some diseases -- cancer, for example -- the immune system appears ineffective in eliminating the "foreign" cancer cells. Immunotherapy is an attempt to strengthen the immune system in its fight against the cancer. In some diseases caused by viruses, not enough of the body's own natural anti-viral molecules (like the interferons) are produced by the body.

What does anovulation mean — can it effect the ability to get pregnant?

DEAR DOCTOR K: I've always had infrequent periods, but I never thought much of it. My doctor recently used the word "anovulatory" to explain why I've had trouble getting pregnant. What does this mean? Could the two be connected?

DEAR READER: "Anovulation" means you are not ovulating -- releasing eggs. A woman's ovary should release approximately one egg each month. Once released, the egg travels into the fallopian tube. There, it can be fertilized by the entry of a sperm. The fertilized egg then enters the uterus. When a woman does not ovulate, no egg is available to be fertilized by sperm. As a result, a woman cannot become pregnant. Women who are anovulatory have irregular, few or no periods.

Is it possible to prevent or reduce your risk of cancer?

DEAR DOCTOR K: Is it possible to prevent, or at least reduce, your risk of cancer?

DEAR READER: Absolutely, it is. It is possible both to reduce the risk that your cells will turn cancerous, and to catch cancer early and prevent it from causing suffering. But first let's define some terms. What does it mean to say that a "cell turns cancerous"? Cancer is uncontrolled cell growth. Most cells "grow" not by becoming larger, but from dividing. (An exception: Fat cells grow not only by dividing, but also by becoming larger.) One cell becomes two, two become four, four become eight, and so on.

What’s the treatment for a subdural hematoma?

DEAR DOCTOR K: My mother is in her 70s. She fell a few weeks ago but seemed fine. Then she started to have double vision and some trouble with balance. A CT scan revealed a subdural hematoma. Her doctor advised only bed rest and medication. Does this seem reasonable to you?

DEAR READER: A subdural hematoma (or hemorrhage) occurs when blood vessels near the surface of the brain burst. Blood collects beneath the dura mater. That's the outermost layer of the brain's protective covering. Here is an illustration of a subdural hematoma:

What’s the difference between a good and bad carbs?

DEAR DOCTOR K: In your column you often distinguish between "good" and "bad" carbohydrates. What makes a carb good or bad?

DEAR READER: Carbohydrates -- carbs -- occur naturally in a variety of foods, from fruits, vegetables and milk, to breads, cereals and legumes. Carbs are also added to many foods, often in the form of sugar. Your digestive system transforms carbs into glucose (blood sugar). They are your body's main source of energy. Whether a carb is "good" or "bad" depends on several factors. Some of the most important are:

Do eating and bowel habits change as we age?

DEAR DOCTOR K: As I've entered my 70s, I've noticed that my eating and bowel habits have changed. Is this normal?

DEAR READER: Well, I could tell you what it says in the medical textbooks, or I could speak from personal experience. The answer would be the same: It sure is normal. Aging most definitely affects our eating and bowel habits. The human digestive system -- our gastrointestinal (GI) tract, or "gut" -- is a series of hollow organs linked to form a long, twisting tube. It begins at the mouth and winds down through the esophagus, stomach, small intestine and colon. These organs break down food into components that the body can absorb and use for energy. What's left is expelled by an efficient disposal system.

Do children who sleep less weigh more?

DEAR DOCTOR K: I recently saw a headline that said children who sleep less weigh more. Is that true? How much sleep should my preschooler and first-grader get each night?

DEAR READER: I believe you're referring to a study recently published in the medical journal Pediatrics. Researchers found that children who don't get enough sleep may also have a higher risk of being overweight. Researchers from Harvard-affiliated Massachusetts General Hospital for Children kept track of more than 1,000 children from the ages of 6 months to 7 years. They asked mothers how much sleep their children got at the age of 6 months, 1 year, and then every year until the end of the study.

Should I request advanced cholesterol testing?

DEAR DOCTOR K: Should I request "advanced" cholesterol testing at my next checkup?

DEAR READER: A standard cholesterol test, or lipid profile, measures levels of HDL, LDL, total cholesterol and triglycerides in the blood. So-called "advanced" cholesterol testing is a more detailed version of this test. Cholesterol is a waxy, yellowish fat. It travels through your bloodstream in tiny, protein-covered particles called lipoproteins. These particles contain cholesterol and triglycerides, a type of fat.

Is there a surgical fix for obstructive sleep apnea?

DEAR DOCTOR K: Is there a surgical fix for sleep apnea? I've tried CPAP and a couple of other treatments, and none of them work well for me.

DEAR READER: Sleep apnea is a condition in which breathing stops intermittently, or becomes shallower, during sleep. Obstructive sleep apnea (OSA) is the most common form. OSA occurs when muscles in the back of your throat relax as you sleep. This causes the airway -- the space in the back of your throat through which air passes when you breathe -- to periodically collapse. If air can't get into your lungs, oxygen levels in your lungs drop, which then causes oxygen levels in your blood to drop.