DEAR DR. DONOHUE: Is polycystic kidney disease inherited? My son-in-law has it. Will his children get it? – G.G.

DEAR DR. DONOHUE: My husband has polycystic kidney disease and has pain on one side of his back. Are there any treatments for it? – B.L.

ANSWER: Polycystic kidney disease – PKD – is one of the most common genetic illnesses. Children of a patient have a 50 percent chance of developing it.

I am speaking of the most common variety, called autosomal dominant polycystic kidney disease.

Most of the time, the condition is silent until the 20s or 30s, when high blood pressure brings a person to the doctor.

High blood pressure at a young age raises the question of PKD, and the doctor can often feel the enlarged, cystic kidneys.

An ultrasound picture of the kidneys clearly shows the cysts.

A large cyst can be painful. Before reaching for pain medicine, however, it is wise to see the doctor, because kidney infection, kidney stones or even kidney tumors could also be the source of pain, and deadening the pain without knowing its cause would camouflage those conditions. If the pain comes from a large cyst, then draining it can often ease the discomfort.

The course of this illness is variable. Rigorous control of blood pressure is essential to preserve kidney health.

By their 50s or 60s, some patients’ kidneys will have failed, and those patients require dialysis. Kidney transplant is highly successful for people with PKD – if and when they ever need it.

Let me give both of you and all polycystic kidney patients the number of the Polycystic Kidney Disease Foundation – 1-800-PKD-CURE. Its Web site is www.pkdcure.org. The foundation can provide you with the latest information on the illness and its treatment. Contacting the foundation is a move you will not regret.

DEAR DR. DONOHUE: I am a male, 73, and take zinc tablets, 50 mg, daily. Is this a good idea? Someone told me that too much zinc causes the prostate to enlarge. Does it? – D.O.

ANSWER: Zinc supports the action of 100 or so enzymes – proteins inside all body cells that keep cell chemistry perking along at optimum rates. It’s also essential for wound healing, and it plays a role in maintaining the senses of taste and smell.

The recommended daily allowance for adult men is 11 mg, and for adult women, 8 mg.

Doses of 100 mg or more a day increase the risk for prostate cancer. High doses might weaken the immune system, and they can lower HDL cholesterol – the good kind of cholesterol, the kind that prevents heart attacks and strokes.

High doses interfere with absorption of copper, another mineral that has important body functions.

The vitamin-mineral treatment that is used to slow the progress of macular degeneration calls for 70 to 80 mg of zinc a day. Such a dose is fine if it’s been suggested by a doctor and if it is being monitored by one.

Why are you taking a higher-than-recommended allotment of zinc?

DEAR DR. DONOHUE: What is a systolic ejection murmur, grade 1-2/6? Is it serious? I do not feel bad. – C.P.

ANSWER: Systole (SIS-toe-lee) is the part of the heart cycle when the heart muscle contracts to eject blood into the general circulation. Systolic murmurs, especially soft ones like your 1-2/6, are often innocent murmurs, ones that don’t indicate any heart trouble like narrowed or leaky heart valves. Not all systolic murmurs are harmless, and the doctor has to judge the murmur’s significance on many other signs. If that presents a problem, sound wave pictures of the heart resolve any question about the murmur’s importance.

Diastolic murmurs, the ones that are present when the heart is relaxing between heartbeats, are almost always a harbinger of trouble.

DEAR DR. DONOHUE: I have an itch on both my arms that is driving me wild. In the morning I wake with blood on the sheets that comes from scratching during sleep. I am not allergic to anything. My wife has changed the laundry soap. My diet hasn’t changed. What could this be, and how do I get rid of it? – J.L.

ANSWER: It could be eczema (EK-zuh-muh or ek-ZEE-muh), an outbreak of small blisters on red skin that brings an itch of fierce intensity. It’s what’s called an autoimmune problem, one where the body’s immune system turns against its own tissues and organs – in this case, the skin.

Give the following a try. Buy a tube of cortisone cream or ointment from the drugstore. The pharmacist can help you find one. Apply it three times a day, with the final application being just before bedtime, when your wife wraps your arms with something like clear plastic wrap. The covering makes it easier for cortisone to penetrate the skin.

Don’t scratch. Scratching brings a few seconds of blessed relief, but the itch always returns and sometimes intensifies. Scratching causes the skin to thicken and dry, and opens the door to infection.

Wash with tepid water and used a nonirritating soap like Dove, Alpha Keri or Neutrogena. Don’t dry the arms completely. Leave a film of moisture on them. When you are no longer using cortisone, cover the arms, after washing, with a light coat of a moisturizing cream.

If things have not turned around within a week, you have to see a doctor. The doctor can confirm the diagnosis and prescribe medicines that are more potent than the over-the-counter variety.

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.