DEAR DR. DONOHUE: Could vitamin B-12 in skin patches be provided for all of us with pernicious anemia so that we wouldn’t have to suffer from monthly injections? — B.W.

ANSWER: No skin patch has been devised for delivery of vitamin B-12. However, it is acceptable to take B-12 by mouth. The vitamin dose given is very high, since only small amounts are absorbed by people with pernicious anemia. Oral treatment is common in Europe. There also are under-the-tongue preparations and nasal sprays of B-12 that can be used. Shots are favored here because they are the most certain way of delivering enough of the vitamin.

People not familiar with the PA story need some background information.

Pernicious anemia results from a deficiency of vitamin B-12. For absorption into the blood from the digestive tract, vitamin B-12 requires a substance made by the stomach called intrinsic factor. Intrinsic factor takes the vitamin by the hand and leads it across the intestinal lining and into the blood so that it gets to the bone marrow, where it’s needed for the production of red blood cells. B-12 has another important function: It keeps nerves healthy.

People with PA have an immune system that attacks the stomach cells producing intrinsic factor. Without it, too little B-12 is absorbed. In time, symptoms of anemia arise: fatigue and breathlessness with little activity. The tongue might turn red and become sensitive. Nerve problems, like having peculiar sensations or numbness, or muscle weakness or trouble walking, appear.

Restoration of the body’s supply of B-12 reverses the anemia symptoms. It also reverses nerve damage if treatment is begun early. Shots of the vitamin do away with the need for intrinsic factor.

Treatment is a lifelong proposition.

DEAR DR. DONOHUE: In a recent column on colon cancer, you note that if no problems are found on colonoscopy, a repeat isn’t needed for 10 years. What is the length of time it takes for a polyp to become a cancer? I have heard of people coming down with it a year or so after a clean colonoscopy. You also mentioned that it’s OK to stop colonoscopies at age 75 if the previous ones have been normal. What about recent published findings that age 75 is the peak year for colon cancer? — H.H.

ANSWER: It takes five years for a polyp to become a significant problem. That’s a general rule. Always, there are exceptions to such rules.

The latest information on the peak ages for colon cancer that I can find are the ages between 60 and 70. That comes from The Pathological Basis of Disease, 8th edition, 2010, by Kumar V., et al.

Some other interesting polyp facts are that only a minority of them become cancerous; 30 percent of middle-aged people have one or more; and 50 percent of older people have a polyp or polyps.

The booklet on colon cancer explains its diagnosis and treatment. To obtain a copy, write: Dr. Donohue — No. 505, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I have a dry nose that bleeds occasionally. I apply A+D ointment to my nostrils every few weeks to counteract the dryness. It has petrolatum as an ingredient. Do I have to worry about doing this? The enclosed articles are my concern. — G.W.

ANSWER: The enclosed articles warn about getting oil-based products like petrolatum into the lungs. Large gobs of petroleum jelly or similar products pose a theoretical risk of this happening. But a light coat isn’t likely to make its way into the lungs. I’m sure you can continue doing as you have been doing without putting yourself in any danger.

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.

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