DEAR DR. DONOHUE: After months of suffering from dry eyes, fatigue and painful joints, my son has been diagnosed with Sjogren’s syndrome. His doctor says the disease is seldom life-threatening. Other sources are not so reassuring. Will you comment? – E.B.

ANSWER: Sjogren’s (SHOW-grins) syndrome results from the destruction of salivary and tear glands by an immune system that prompts lymphocytes, one variety of white blood cells, to infiltrate those glands. Without a film of tears, the eyes feel like someone has thrown sand in them. Without saliva, the mouth becomes the Sahara Desert. Some patients also have achy joints and large lymph nodes. Fatigue can be part of the picture.

Most Sjogren’s patients have a normal life span. A few, however, develop lymph-node cancer – lymphoma – and that can shorten life. And sometimes, Sjogren’s follows on the heels of another illness, such as rheumatoid arthritis, lupus or hepatitis. Those illnesses can shorten a person’s life, but your son fits the picture of primary Sjogren’s syndrome, the kind that comes on without any relationship to any other sickness.

There is no cure medicine for Sjogren’s, but there are several effective treatment medicines.

Artificial saliva can keep the mouth moist. Some brand names are Salivart and MouthKote. Evoxac and Salagen are two medicines that can stimulate saliva production even in salivary glands affected by Sjogren’s.

Artificial tears provide a liquid film for the eyes. HypoTears, Refresh Tears and Liquifilm are a few examples of such products. Restasis eyedrops, a new medication, fight the immune attack on the tear glands and soothe dry, irritated eyes. Eye doctors can temporarily plug the tear ducts to prevent loss of the tears that are still made. If the temporary procedure works well, then the ducts can be permanently plugged.

Information on Sjogren’s is too vast to thrust on a person at one sitting. Your son should take advantage of the Sjogren’s Syndrome Foundation. It provides people with information and updates them with the latest in treatment. Have him call the foundation at 1-800-475-6473 or look it up on the Internet at www.sjogrens.org.

DEAR DR. DONOHUE: Recently I was told that my potassium level was slightly high and to stop taking vitamins. What causes this, and what is the result of too much potassium? Why no vitamins? – E.L.

ANSWER: When the kidneys are working well, blood potassium levels stay on an even keel. Poorly functioning kidneys, therefore, are one reason why the blood potassium level rises. Adrenal-gland failure is another reason for a rise in blood potassium, because the adrenal glands make hormones that regulate potassium balance. Body cells are the place where the most body potassium is stored. Cell trauma – even from a bump or fall – can cause cellular release of potassium into the blood.

Very often a slight potassium rise comes from a hitch in the way that blood was collected. If a tourniquet was left on the arm too long when blood was drawn, blood potassium is spuriously raised.

A true rise in potassium can weaken muscles. It throws off the body’s acid-base balance. It interferes with the normal heartbeat and can affect nerve transmission.

Vitamins have no effect on blood potassium. I don’t know why the vitamin ban was given to you.

The booklet on potassium and sodium gives the details of these minerals. Readers can obtain a copy by writing: Dr. Donohue – No. 202, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.50 U.S./$6.50 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: A young doctor once said to me that most doctors do not consider homocysteine important but talk only about cholesterol. Your reply would be appreciated. – A.L.

ANSWER: Homocysteine (HOE-moe-SIS-teen) is an amino acid, and amino acids are the building blocks of protein. High blood levels of this amino acid can indicate artery-clogging problems that lead to a heart attack or stroke. Currently, however, there is not enough evidence to warrant a public alert for universal homocysteine testing.

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.