DEAR DR. DONOHUE: My 6-year-old grandson just had kidney stones. He is healthy in all other respects. Is this unusual for a 6-year-old? What caused it? – S.P.

It is unusual, but not unheard of. About 7 percent of all kidney stones in North America are found in children younger than 16.

Kidney stones occur when the urine concentration of minerals or other substances, like amino acids, becomes so great that those substances cannot stay dissolved. It’s like putting too much sugar in a cup of coffee. No matter how much you stir, all the sugar won’t dissolve; some remains at the bottom of the cup. In the kidney, the undissolved material sticks together to form a stone.

It is important to have a kidney stone analyzed for its composition. That provides information necessary to prevent a second occurrence of stones. The most common childhood kidney stone, as well as adult, is calcium oxalate stone. Your grandson’s doctor will have to determine why he has too much calcium in the urine if he had a calcium stone.

In children, some metabolic problems lead to kidney stones. One of those problems is a condition call cystinuria. Cystine is an amino acid. Amino acids are the basic units of proteins. In this inherited disorder, an abnormal amount of cystine stays in the urine and aggregates to form a stone. If these children’s urine is kept free of acid, cystine stones don’t form.

Children with constant urinary tract infections due to a defect in the tract’s anatomy are also prone to forming stones. Such defects can often be corrected surgically.

The doctors taking care of your grandson will look hard for any correctable condition he might have. If they can’t find one, then the child will have to do what adult kidney stone formers do – drink plenty of fluids to keep the urine dilute.

DEAR DR. DONOHUE: I can’t see the nipples on my breasts. I can’t remember when I could see them. My breasts are quite large. My husband-to-be wonders if I’ll be able to breastfeed our children. He also wonders if there’s something wrong with my breasts. I think he means cancer. Is this a sign of trouble? – H.L.

Frequently, hidden nipples are simply buried in the abundant tissues of large breasts and don’t indicate any medical problem. They are not a cancer sign. Pushing down the adjacent tissue exposes the nipples.

Sometimes bands of scar tissue hold the nipples inward. Such nipples don’t protrude when the surrounding tissue is squeezed. This is something present from birth, and it doesn’t point to cancer either.

Breastfeeding is possible in both cases. If there is any difficulty in doing so, there are plastic shields that fit over the nipples to draw them out.

The inversion of breast nipples that previously had been in their normal position can be a dangerous sign. That’s something that has to be brought to the attention of a doctor.

If you want, surgery can be done to evert the nipples. If your breasts are so large that they are painful, breast reduction is a reasonable remedy.

DEAR DR. DONOHUE: I have a prickly sensation in the little finger of my left hand. Sometimes I feel it in the ring finger too. I can move both fingers, and they really aren’t painful, but I wonder what this means. Can you tell me? – R.N.

It could be cubital tunnel syndrome. Have you heard of carpal tunnel syndrome? It’s a common condition caused by pressure on the large nerve that enters the middle of the hand through a tunnel of ligaments and bones. When compression from swollen tissues squeezes that nerve, symptoms similar to yours happen in the thumb, index and middle finger.

Another large nerve, the ulnar nerve, enters the wrist through a tunnel on the little-finger side of the wrist to produce peculiar sensations in the little and ring fingers when it’s compressed. The ulnar nerve is also vulnerable to pressure at the back of the elbow. A wrist splint might help you. If the fingers become weak or the pain intolerable, you need to seek medical treatment.

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

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