DEAR DR. DONOHUE: Some time ago you wrote an article that involved slow digestion and described what occurs to people who have it. You also mentioned a medicine for it. Will you repeat that information? I would like to show it to my family doctor. – L.A.

ANSWER: The condition is gastroparesis.

Normally food stays in the stomach for three or four hours. The stomach grinds it up and starts digesting it. In people with gastroparesis, it takes food forever to pass through the stomach. Slow passage of food gives rise to nausea, vomiting, bloating, stomach discomfort and a feeling of being stuffed after having eaten only a small amount.

Some illnesses lead to gastroparesis. Diabetes is the chief one. Parkinson’s disease, some cancers, thyroid gland disorders and a rare condition called amyloidosis can bring it on. Other times, no cause is found. They just have it.

The diagnosis is made in a number of ways. One of the best ways is to give the patient a meal that contains radioactive tracers. After the person eats, the stomach is scanned at one, two, three, four and six hours. The scans tell precisely how much food passes through the stomach at those times.

If gastroparesis is diagnosed and an associated illness is found to be the cause, treatment consists of treating the causative illness. If no contributing illness is discovered, a medicine like Reglan (metoclopramide) is prescribed to speed the transit of food through the stomach.

DEAR DR. DONOHUE: It seems that no doctor deals with fingernails. Through the years, I have asked several doctors, and they ignore my question.

My nails don’t grow well. They split and peel, and are very soft. It doesn’t take much to dent one or to break one. I take good care of my nails, but it doesn’t seem to help. Any suggestions will be appreciated. – L.V.

ANSWER: Nails are the specialty of dermatologists. Nails are considered skin appendages.

Let me give you the advice given to me by a reader with your problem. She said she solved it by buffing her nails with a nail buffer.

A standard regimen is as follows: Protect your nails from soaking up water and drying out by wearing rubber gloves whenever you have to put your hands in water. Immersion in water makes nails swell. When they’re taken out of water, the nails dry and shrink. It’s like the freeze-thaw cycles that ruin Northern roads.

Apply moisturizers to the nails three times a day and again at bedtime. Look at the contents of the moisturizer. It should have lactic acid or alpha hydroxy acid. Petrolatum (Vaseline), mineral oil, lanolin and glycerin are other good moisturizers.

Use a soft file to keep the nail edge smooth and short.

Massaging the nail fold is said to promote nail growth and nail strengthening. The nail fold is the cuticle at the bottom of the nail. Many claim that the B vitamin biotin builds sturdy nails.

DEAR DR. DONOHUE: My son, 56, has many large blotches on his legs, arms and face where the pigment is gone. The skin is white. Can you tell me what this is and what can be done for it? – E.H.

ANSWER: It fits the description of vitiligo, the disappearance of pigment-containing skin cells. The involved skin turns white and is quite susceptible to sunburn. The probable cause is an attack by the immune system on the pigment-containing cells.

Some illnesses are associated with vitiligo: thyroid problems, adrenal gland malfunctions and pernicious anemia, but for most, it’s something that just happens on its own.

Cortisone medicines applied directly to the white patches, medicines that sensitize the patches to light therapy and drugs that restrain the immune system are some of the treatments available for vitiligo.

DEAR DR. DONOHUE: Does having legs of different length cause scoliosis?

I have scoliosis, and my doctor tells me that the curvature will progress 1 percent every year. Will wearing a lift for my shorter leg stop the progression? I am 74. – N.B.

ANSWER: Scoliosis is a curve of the backbone either to the right or the left. Most often it’s discovered in youth. The curve progression often slows later in life.

The amount of curve is determined through X-ray analysis of the spine and is given in degrees. In adults, curves less than 40 degrees rarely progress.

If they do, they do so slowly. Curves greater than 40 degrees can progress by one degree each year.

Leg length discrepancy greater than half an inch (1.27 cm) influences the direction of the curve and can accelerate its advance. A shoe lift, therefore, might slow progression.

How great is your curve? Has it progressed in the past few years? If it isn’t a big curve and if it hasn’t increased in degrees in the past few years, it’s not likely to do so now.

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