DEAR DR. DONOHUE: My daughter-in-law has dry mouth syndrome. She has had it for seven months. She has had numerous tests, with no results. She has constant burning in her mouth. She can’t eat anything except mashed potatoes and baked fish. She has lost a lot of weight and is getting very depressed. Do you have any information regarding this? — L.J.

ANSWER: As with any other illness, doctors have to look for the cause in order to prescribe effective treatment. Dry mouth has many causes. Inflammation of the salivary glands, obstruction to the flow of saliva, the side effects of many medicines, diabetes and sarcoidosis are a few of those causes.

If no cause can be found, then your daughter-in-law has to practice things that keep the mouth moist. Saliva does more than moisten the mouth. It protects teeth against decay from mouth bacteria. It starts the digestion of food. A dry mouth makes swallowing food difficult. People with it complain of a burning-mouth sensation. She should have a squeeze bottle of water with her at all times, and she should use it constantly. Chewing sugarless gum stimulates the production of saliva. Artificial salivas are in all drugstores. OraMoist, Biotene (many products) and Numoisyn lozenges and liquids are but a few of the products available. Medicines like pilocarpine and Evoxac increase saliva production.

Her doctor has to consider the possibility of Sjogren’s (SHOW-grins) syndrome, an autoimmune attack on the salivary glands and often the tear glands. The famous tennis player Venus Williams recently was diagnosed as having it. Autoimmune diseases indicate that the immune system, the system that protects us from infections, for reasons no one understands, considers certain body organs to be an enemy and sets out to destroy them. In this case, those organs are the salivary and tear glands. Testing is essential to diagnose this illness. Special antibodies in the blood are one sign of it.

Sometimes symptoms in places other than the mouth and eyes occur. Arthritis, for example, is a frequent companion of Sjogren’s.

Your daughter-in-law can learn the ways to keep her mouth healthy by contacting the Sjogren’s Syndrome Foundation at www.sjogrens.org or 800-475-6473.

She can keep her weight up by drinking supplements like Ensure.

DEAR DR. DONOHUE: In 2006, we lost our mother. She was 89. The autopsy report concluded that she suffered from progressive supranuclear palsy. Her final six years were hell on her. What, if any, are the genetic implications of progressive supranuclear palsy? — B.B.

ANSWER: Frequent, unexpected falls, especially backward falls, difficulty walking, red eyes, blurred vision, apathy and slow, slurred speech are some of the signs of progressive supranuclear palsy. With progression of the illness, people are unable to look down and up. The onset of this illness often begins in the 50s.

Only rare cases of family clusters have been found, so the genetic influence in this disease isn’t present in the majority of cases.

For in-depth information, contact the Foundation for Progressive Supranuclear Palsy at www.curepsp.org.

DEAR DR. DONOHUE: My family doctor sent me for blood work as part of a routine checkup. She called me to let me know that everything was normal. Later I picked up a copy of the lab report for my gyn doctor. That doctor was concerned that my neutrophil count was 4,200 and my eosinophil count was 650. What do these numbers mean? — M.D.

ANSWER: Your neutrophil count is normal. Neutrophils are white blood cells that go after germs.

The normal eosinophil (another white blood cell) count is zero to 540. Yours is slightly high — so slightly that it doesn’t warrant worry. Higher eosinophil counts are seen with allergies, parasite infections and some forms of arthritis.

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 www .rbmamall.com.