DEAR DR. DONOHUE: Is it true that emphysema can be reversed and cured by rebuilding alveoli in the lungs by taking Tretinoin (retinoic acid)? – R.K.

ANSWER: Emphysema is the permanent destruction of many of the lung’s more than 200 million alveoli – its tiny, delicate air sacs. Oxygen passes from inhaled air through those air sacs into the blood for delivery throughout the body. Carbon dioxide, the waste gas of body metabolism, passes out of the blood and into the air sacs, and is exhaled.

Symptoms of emphysema are difficulty breathing and a state of constant hunger for air, since the body is in a state of oxygen deprivation.

Tretinoin – retinoic acid – belongs to a family of substances that have vitamin A activity. Vitamin A is involved in many body processes, one of which is the building and maintenance of cell walls. It is not a stretch, therefore, to imagine that it could rebuild air sac walls. But read on.

The medicine is mostly used for skin conditions like acne. It comes in creams, gels and liquids for external use. An oral form of the drug is available for certain blood illnesses. I cannot find any information that Tretinoin benefits emphysema. If there were even a hint that it might be beneficial, headlines would have announced the news.

Although emphysema is a permanent condition and although there is no cure drug at present, there are ways of dealing with the problem. Enrolling in a pulmonary-rehabilitation program, available in many hospitals, is one way. In such programs, breathing techniques are taught. Pursed-mouth breathing is an example. Emphysema patients breathe in through the nose. To exhale, they tighten their abdominal muscles so the chest is pushed upward while they breathe out through lips pursed as though they were drawn up to whistle. An exhalation should be slow – twice as long as an inhalation.

DEAR DR. DONOHUE: What should I do for Perthes’ disease? I had surgery about eight months ago. Are there any exercises I should do? – Your friend, S.R., age 9

ANSWER: With Perthes’ disease, which happens mostly to children between the ages of 2 and 12, the blood supply to the top of the thigh bone is suddenly cut off. No one has been able to give a good explanation why it happens.

The result is that the section of bone, deprived of blood, stops growing. Then it begins to crumble. The child develops a limp that is sometimes painful.

All this sounds terrible, S.R., but don’t lose hope. Eventually the crumbled bone is absorbed by the body and replaced by new bone. That can take time, sometimes a year or more. But it almost always takes place and almost always with a good result.

During the active phase of Perthes’, when X-rays show that the top of the thigh bone is not forming in such a way that it fits perfectly into its socket, surgery is done to correct matters. On some occasions, braces must be worn.

The only exercises you should do are the ones given to you by your doctor or by a physical therapist referred to you by your doctor. Every case of Perthes’ is a bit different, so therapy for each case differs somewhat.

This illness also goes by the name Legg-Calve-Perthes disease.

DEAR DR. DONOHUE: How much beer can a person consume a day before it is harmful? My husband drinks at least six to 12 beers a night after work, and he drinks more on weekends. He doesn’t consider himself an alcoholic, but he shakes so bad in the mornings that he can hardly hold a cup of coffee. – C.R.

ANSWER: A man should limit himself to two alcoholic drinks a day; a woman, to one. A drink is 12 ounces of beer, 5 ounces of wine or 1.5 ounces of liquor.

Your husband is an alcoholic. His morning shakes show that he is. They’re a sign that his brain is experiencing alcohol withdrawal after sleeping for some hours without having any alcohol.

DEAR DR. DONOHUE: Would you explain the causes of angioedema? – J.G.

ANSWER: Angioedema, also called angioneurotic edema, is a reaction very much like hives. It occurs for the same reasons. It’s a leaking of fluid (“edema”) from blood vessels (“angio”). The reaction can occur just about anywhere – the lips, the tongue, the eyelids, the face and the arms. If it happens in the airways, it can be a danger. Massive swelling can cut off the flow of air into the lungs.

Food allergies are a frequent cause. On the list of suspect foods are shellfish, fish, milk, chocolate and nuts. Even things like cold, heat or sunlight can lead to angioedema. Exercise causes it in some. For a few, it’s an inherited condition. By far and large, however, a cause is never found, and the condition is labeled “idiopathic” – “cause unknown.”

Antihistamines can often end an attack. If a swollen tongue or swollen airways have been a problem, such attacks make it mandatory for people to carry an emergency kit containing injectable Adrenalin to quickly end one.

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.