How can I prepare my son to be a responsible driver?

DEAR DOCTOR K: My son is going to get his driver's license in a few months. How can I help him get ready for this new responsibility?

DEAR READER: Taking the test to get my first driver's license was one of the most emotionally charged moments of my teenage years. Being able to drive oneself around is an important step toward independence. Boy, did I want that independence.

What helps relieve interstitial cystitis symptoms?

DEAR DOCTOR K: I have interstitial cystitis. Medications have helped, but not much. What else could help relieve my symptoms?

DEAR READER: Interstitial cystitis is a puzzling bladder condition in which the bladder wall becomes irritated or inflamed. We don't know what causes the condition. Some doctors speculate that an infection, most likely with viruses, is responsible. However, I'm not aware of any good evidence in support of that. The symptoms of interstitial cystitis are similar to those of a bacterial urinary tract infection.

Can depression increase my craving for sweets?

DEAR DOCTOR K: I am a 50-year-old woman with a history of depression. I recently developed an uncontrollable craving for sweets, which has increased my weight. Is it my depression or my medicine?

DEAR READER: You are right to wonder about the cause of your craving. It could be triggered by your depression or by the medicine you are taking to manage it. Or by something else entirely.

How much protein do we need in our diet?

DEAR DOCTOR K: How much protein do I need? Should I drink protein shakes to make sure I get enough?

DEAR READER: Protein is important for building and maintaining muscle and bone strength. It is necessary for the body's skin and hair cells to grow and repair. It also sends signals to your brain that you are full and have had enough to eat. People in the developing nations who cannot find enough protein to eat develop two terrible and sometimes fatal diseases, kwashiorkor and marasmus.

Could something other than depression be affecting my mood?

DEAR DOCTOR K: I've been feeling down and moody lately, but nothing out of the ordinary has happened in my life. And I've always been a happy and positive person. Could something other than depression be affecting my mood?

DEAR READER: Depression is a common problem, and it often is not recognized by either the person suffering from it or that person's doctor. In fact, I think undiagnosed and untreated depression is one of the most important health problems in the developed nations. It generates enormous emotional suffering -- on the part of the depressed person, and that person's family, friends and co-workers. It also leads to lost productivity.

My doctor thinks I have rheumatoid arthritis — so why is she testing me for lupus and gout?

DEAR DOCTOR K: My doctor suspects I have rheumatoid arthritis, but she wants to test me for several other disorders, including lupus and gout. Why?

DEAR READER: Several other diseases can cause symptoms and joint changes that are similar to rheumatoid arthritis (RA), including lupus and gout. That's probably why your doctor is ordering the tests. She suspects you have RA, but she won't know for sure unless she rules out these other diseases.

When should I talk to my child about sex?

DEAR DOCTOR K: When should I start talking to my child about sex? And what topics should I discuss?

DEAR READER: Many parents are uncomfortable talking about sex with their kids, but they know the day will, and should, come. They often anxiously prepare in advance what they will say if their child asks a question about sex.

Why do I need to have another pneumonia vaccine?

DEAR DOCTOR K: I'm 70 years old. I already had a pneumonia vaccine, back when I was 65. At my checkup last week, my doctor said I need to get another one. Why?

DEAR READER: I always like to hear that adults are staying up to date with their vaccinations, as you did when you received a dose of the PPSV23 (Pneumovax) vaccine at age 65. Pneumovax helps protect against pneumonia caused by one common type of bacteria, called pneumococcus.

How do vaccines work?

DEAR DOCTOR K: You've written many columns about vaccines. Can you explain how they work?

DEAR READER: A vaccine prompts your immune system to build immunity against a particular germ. It mimics what would happen naturally if the germ entered your body. In order to understand how vaccines work, though, it helps to understand how your body's immune system works.

What helps us balance?

DEAR DOCTOR K: What are the body parts, or systems, that help us balance?

DEAR READER: You're asking a very interesting question. I never even thought about it until I went to medical school. When I learned what I'm about to tell you, I thought it was interesting. However, I didn't appreciate how important problems with balance would be for my patients.