DEAR DR. DONOHUE: I would like your opinion on the causes of avascular necrosis. I am a 58-year-old man who started working in a grocery store when I was 18. I was a meat cutter for 18 years and on my feet for eight or more hours a day with constant bending and lifting. For the past 22 years, I have stocked grocery shelves. It requires heavy lifting, walking and bending. I had 40 years of hard, physical work.

I fell off a 3-foot ladder and injured my left hip. After two months of medication for pain and swelling, I had an MRI on my hip. It showed avascular necrosis. Since then, I have had a hip replacement.

One doctor told me that the fall from the ladder severed an artery in my hip, which caused the necrosis. Another doctor told me that neither the fall nor my 40 years of work was a cause. What do you think? – M.P.

ANSWER: Avascular necrosis also goes by the name osteonecrosis – literally, bone death. About 15,000 people each year suffer from it. It’s an interruption of blood supply to part of a bone. Without blood, that portion of bone dies. Quite often, leg bones are the target, and the hip is one of the principal places for it to happen. An artery to the bone is not severed; there’s a mysterious disappearance of the blood vessels that serve the section of involved bone.

Pain on walking is the outstanding symptom.

The causes of osteonecrosis are many. People with sickle cell disease can get it. So do those who have lupus or gout. Pregnancy can bring it on. Cigarette smoking and heavy alcohol use have been implicated. A hip fracture or hip dislocation can lead to it. For many, no cause is ever found.

Treatment depends on the extent of bone death and the state of the hip joint. Sometimes, as in your case, a hip replacement is necessary.

DEAR DR. DONOHUE: I am a 65-year-old man. I am not obese. I have been diagnosed with meralgia paresthetica. What exactly is this, and what treatments are available for it? What is the long-term outlook for this condition? – M.T.

ANSWER: Meralgia (mur-AL-gee-uh) paresthetica (PAIR-is-THET-ee-kuh) brings on burning pain or peculiar sensations or loss of feeling on the front and side of the upper thigh because the nerve serving that area is being compressed. The compression can come from fat, from a tool belt, from tight pants or from just about anything that presses on the nerve. A cowboy’s belt and holster are classic causes of this somewhat-common condition. The holster covers the area involved with pain or lack of sensation.

Treatment lies in relieving the compression. On rare occasions, a surgeon must free the nerve from whatever entraps it.

The long-term outlook is usually quite good.

DEAR DR. DONOHUE: What cause could be making a 29-year-old man have sexual relations only when intoxicated? He is healthy, married and affectionate, but he does not initiate love-making when he’s sober. Is there a physical problem here? – R.R.

ANSWER: More likely there’s a psychological problem. If he had a physical problem, alcohol would not get rid of it. The alcohol relaxes him so he can function.

This young man should start with his family doctor, who can look for physical causes. If the doctor doesn’t find any, then he can refer the man to a specialist who can uproot any psychological problem.

DEAR DR. DONOHUE: What is TENS? – Y.M.

ANSWER: TENS – transcutaneous electric nerve stimulation – is a battery-powered device with electrodes that are applied to the skin over an area of pain. The electric current it generates blocks pain sensations from reaching the brain. It works for some, but not all. Sometimes these devices can be rented to see if they’ll work for a particular individual.

DEAR DR. DONOHUE: I am a 63-year-old woman, 5 feet 10 inches tall and weighing 159 pounds. I bicycle two miles a day and walk on a treadmill every day for half an hour. I also lift weights. I had my ovaries and appendix removed a few months ago, and ever since, my blood pressure has gone up. My doctor put me on medicine. I hate pills.

I have attached a summary of my pressures. What do you think? Everyone says not to start blood pressure medicine – like it would kill you. I don’t know what to do. – E.S.

ANSWER: Blood pressure medicines don’t kill. They save lives. High blood pressure kills.

Normal blood pressure is a reading below 120/80. Readings of 120-139/80-89 fall into a category called prehypertension. Most of your blood pressure measurements fall into this category. Treatment for people with prehypertension usually is conducted without medicine. People are told to lose weight. You don’t need to. Your body mass index – a better indicator of healthy weight than what the scales show — is normal. I calculated it. Prehypertension people are also told to exercise. Your program is as good as they come.

What’s left? You have to cut back on your salt – not just pushing away the salt shaker but paying close attention to the amount of salt (sodium) in all foods. Your diet is one that should consist mostly of fruits, vegetables, whole grains and low-fat dairy products. After two to six months of following such a regimen, your pressure should drop considerably. Ask your doctor if you can try this before stopping medicine on your own. Some people in the prehypertension category must go on medicine if they have an illness, such as diabetes, that predisposes them to heart trouble. Perhaps this is why your doctor has you on medicine.

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