DEAR DR. DONOHUE: My 20-year-old daughter lives at home and goes to a local college. This past year she had a kidney stone that caused her terrible pain. Shouldn’t she be on a diet without calcium? Her doctor has said nothing to her about this. – K.R.

The kind of stone your daughter had forms the basis of prevention strategy. Without that information, I am a little stymied, but I’ll assume she had the most common kind of kidney stone, a calcium stone. Calcium stones are not pure calcium. Always, they are paired with another substance, and the usual partner is oxalate.

In the recent past, the emphasis for calcium oxalate stone prevention was a low-calcium diet. It turns out that such a diet promotes stone formation. When people limit their calcium consumption, oxalate absorption increases, as does oxalate filtration into the urine. Oxalate in the urine encourages stone formation.

The diet emphasis, therefore, is on reducing consumption of oxalate foods, which include spinach, nuts, chocolate, beets and strawberries. Such a diet is not hard to follow.

Your daughter should decrease her intake of meat, the greatest source of protein. Protein encourages stone formation. The same goes for salt. Citrus fruits, on the other hand, inhibit stone formation.

The single most important item in stone prevention is to stay well-hydrated. Your daughter should drink enough water so that her urine is clear. Clear urine is a good marker for adequate hydration.

At least eight 8-ounce glasses of water a day can keep her urine diluted and free of crystals that develop into stones.

Young women have much to be thankful for with the switch from low-calcium diets to low-oxalate diets. Depriving such women of calcium puts them at danger of having osteoporosis later in life.

DEAR DR. DONOHUE: I have a large, swollen testicle that is not painful. I can’t remember having done anything that could have injured it. I have waited two months for it to shrink, but it hasn’t. I am concerned that it might be cancer. Could it? – R.R.

Keep in mind that this is a long-distance diagnosis, so it’s not completely reliable. You must have the family doctor confirm it.

You describe a hydrocele. It’s a collection of fluid within the testicle. If you want proof of its being a hydrocele, go into a dark room with a flashlight. Hold the lighted flashlight to one side of the testicle.

If you can see light shining through the testicle when viewed from the opposite side, that is strong evidence for a hydrocele.

Hydroceles sometimes result from a previous infection or injury. In a truly small number of cases, they are associated with testicular cancer. Most of the time, no cause can be found. They just happen.

Your doctor can put an end to the cancer fear with an examination. If the examination leaves a doubt, an ultrasound picture eliminates it.

If the hydrocele is not painful and is not so large that it makes it awkward to move about, then it can be left alone. Draining the fluid is usually an exercise in futility, because it comes back. Large, uncomfortable hydroceles can be surgically removed.

DEAR DR. DONOHUE: Whenever I rub against something, I get a huge welt on my skin. I showed my doctor, who shrugged his shoulders and said it was nothing to worry about. What is it? Is there any medicine I can take to get rid of this? – D.S.

You have dermatographism – skin writing. With a cotton-tipped applicator, trace your initials on your arm. You’ll find that welts form your monogram.

A tight belt or a tight bra strap also raises welts. Anything that puts pressure on your skin does.

In a small minority of people with dermatographism, an association with thyroid disorders, diabetes or infections can be found. In most, however, it springs up on its own.

You can suppress the outbreaks with antihistamines.

DEAR DR. DONOHUE: Is it possible to develop an allergy to wine? I have drunk a glass of wine with dinner for most of my life. Now, after drinking it, I wheeze and am short of breath. What would you advise? — D.K.

I’d advise seeing the family doctor or an allergist. My hunch is that you might have developed a sensitivity to sulfites.

Sulfites are preservatives that are added to many foods. They occur naturally in other foods. They stop foods from spoiling or changing color.

About one person in 100 becomes sensitive to sulfites. When those people are exposed to sulfites in food or drink, they can have an asthma attack — which it sounds like you are having.

Doctors can detect sulfite sensitivity by challenging a patient with a small amount of sulfite and observing any reaction. They are prepared to terminate a reaction if one occurs.

If it turns out that you are sulfite-sensitive, you have to become a label reader. Look for these words on the labels: sodium sulfite, sulfur dioxide, sodium bisulfite, sodium metabisulfite, potassium bisulfite and potassium metabisulfite.

Many wines contain naturally occurring sulfites.

DEAR DR. DONOHUE: My 13-year-old daughter had her first menstrual period six months ago. Since then she has had only one more period. I took her to the doctor, who told me to stop worrying. I cannot. Is this serious? — P.M.

Menstruation results from a complex interplay of many hormones, and their coordinated action takes time to develop. It is not at all unusual for a girl to have irregular periods and even to have a cessation of periods for as long as one year after her first period.

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.

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