DEAR DR. DONOHUE: If a person has Barrett’s esophagus, is there a need for a yearly exam of the esophagus? Your opinion, please. – A.L.

ANSWER: Barrett’s esophagus springs from gastroesophageal reflux disease – GERD – more commonly known as heartburn.

When stomach acid and digestive juices spurt upward like Old Faithful from the stomach into the esophagus, people feel the pangs of heartburn. The esophagus was not built to withstand those corrosive juices.

Between 4 percent and 10 percent of patients who suffer from GERD develop changes in the cells that line the lower part of the esophagus. That change is the hallmark of Barrett’s esophagus.

If GERD can be prevented, then people do not develop Barrett’s esophagus. Propping up the head of the bed by putting 6-inch blocks under the bedposts keeps stomach juices in the stomach during the night. Avoiding fatty foods, fried foods, chocolate, peppermint, caffeine, citrus fruits and tomatoes is another way to put a stop to GERD and Barrett’s esophagus.

There are many medicines that slow down stomach acid production so heartburn, GERD and Barrett’s esophagus can be nipped in the bud. The names of some of those medicines are: Tagamet, Zantac, Pepcid, Axid, Prilosec, Prevacid and Nexium.

Once Barrett’s changes occur, rarely do they revert to normal. The danger of this lies in the possibility that the altered cells will turn into cancer cells.

For that reason, people who have Barrett’s esophagus are put on a schedule of scope surveillance. The frequency of such exams depends on the changes in the esophagus’s cells. If the changes are slight, yearly exams are acceptable. If they are great, then exams are scheduled for every three or six months.

People wishing for more information on GERD and hiatal hernia can obtain the pamphlet on that subject by writing: Dr. Donohue — No. 501, 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: In about three months I am going to have my first baby. This past week I broke out in an itchy rash. Could it be related to my pregnancy? What can I take for it? – J.S.

ANSWER: Your rash has a number of features of PUPPP: Pruritic (itchy) Urticarial (hivelike) Papules (small skin bumps about the size of a tiny pimple) and Plaques (large bumps) of Pregnancy. Even though it might not have a familiar ring, it is a somewhat common condition. It happens to about one in 160 pregnant women. It usually appears in the last three months of pregnancy. Often it begins on or near the stretch marks that occur on most pregnant women’s abdomens. It can spread to the arms, legs and trunk.

For self-treatment, try oatmeal baths. Aveeno is the name of one oatmeal preparation that can be put into the bathtub.

If relief does not come quickly, see your doctor. I am making only a long-distance guess. You need a doctor’s eyeball diagnosis. Furthermore, you might need prescription medicine to quell the itchy rash.

DEAR DR. DONOHUE: My son, who is in his 40s, had a melanoma of his eye. I know skin melanoma is caused by overexposure to sunlight. My son was a sun worshipper for many years. Did the sun cause his eye cancer? – M.K.

ANSWER: Melanomas are cancers that occur in cells having melanin, a dark pigment. Melanin cells are plentiful in the skin, but they exist in other places as well, including the eye. Ultraviolet light has a hand in skin melanomas. Melanomas, however, can occur in the mouth, the esophagus (the swallowing tube) and even in the lungs, so the ultraviolet rays of sunlight are not the only cause of these cancers.

I cannot say if sun exposure was at work in your son’s eye melanoma. The link between sun exposure and eye melanoma is not as great as it is for skin melanoma.

DEAR DR. DONOHUE: I have entered a 10K (6-mile) race that’s being held in August. I know I should drink lots of water before and during the race, but how much is “lots of”? – N.K.

ANSWER: Now, while you practice running, weigh yourself before the run and after. Every pound of weight lost represents the loss of a pint (500 ml) of body fluid. That gives you a gauge of how much water you need to keep your body hydrated.

If a run lasts more than an hour, include some salt in your replacement fluid. Either drink a sports drink or carry a small container of salt with you and take a pinch of it with every drink of water.

Prolonged runs during which a runner drinks only water can lead to hyponatremia (HI-poe-nuh-TREE-me-uh) – low body salt. People have died from it.

DEAR DR. DONOHUE: Will you answer a few sunglasses questions for me? I used to pick them to make a fashion statement, but I have heard that the wrong kind can cause eye problems. Are dark lenses the best? What color? Do children need to wear them? – L.A.

ANSWER: The most important function of good sunglasses is filtering ultraviolet light. UV light can lead to cataract formation and can damage the most sensitive part of the retina, the macula. These changes occur later in life, but much can be done to prevent them if you are UV-light-protected from an early age.

Read the label on the glasses. You want a pair that filters out ultraviolet rays, both ultraviolet A and B. On some glasses, the label is marked “Z 80.3.” That indicates that the glasses meet the criteria of the American National Standards Institute and block 60 percent of ultraviolet A rays and 95 percent of ultraviolet B.

Glasses that carry a sticker marked AOA (American Optometry Association) block 99 percent of ultraviolet rays. The darkness of the lens has little bearing on its protection. Dark lenses that don’t filter UV light might be more dangerous than not wearing glasses. The dark lens makes the pupil dilate, and more UV rays can enter the eye. As for the shade of the lens, gray, brown and green lenses distort ambient color the least.

Yes, children should wear sunglasses that filter ultraviolet light.

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.