DEAR DR. DONOHUE: Would you write something about heatstroke. It’s not the same as a regular stroke, is it? A friend of mine says it is. What are the warning signs, and how do you treat it? – L.D.

Heatstroke and a regular stroke – a brain stroke – are definitely not the same. A brain stroke comes from a disruption of the brain’s blood supply. A heatstroke, as the name implies, comes from a steep rise in body temperature, which does affect the brain, but it affects many other body organs.

When the ambient temperature is lower than body temperature, the body cools itself by simply transferring heat to the surroundings. Another method for maintaining normal body heat is sweating. The evaporation of sweat has a marked cooling effect.

When the surrounding temperature is high and when the humidity is also high, both cooling mechanisms fail. A temperature of 90 with humidity of 65 percent or a temperature of 86 with a humidity of 85 percent are conditions that can lead to heat injuries.

Heat cramps – muscle spasms – are the first sign of trouble. When they occur, get to a cool, shady place and drink plenty of fluids.

The next level is heat exhaustion. People are played out and sweat heavily. They may be nauseated and dizzy. These people should be taken to an air-conditioned room, with clothes loosened or off, and given fluids.

Heatstroke is a true emergency. The skin is hot and dry, but not always. Early on, it can be pale and wet. People are confused and might even slump to the ground. Body temperature is 104 F (40 C) or higher. These people should be submerged in water with a temperature between 35 F (1.6 C) and 40 F (4.4 C). The high body temperature can cause breakdown of muscles, and the breakdown (rhabdomyolysis) releases products that can shut down the kidneys.

Heatstroke is best treated in an emergency department if the person can be evacuated quickly. Cooling measures can begin en route.

DEAR DR. DONOHUE: I am a 92-year-old man in good physical condition, 5 feet 6 inches tall and weighing 155 pounds. I exercise for an hour or an hour and a half, five days a week, and have been doing so for 14 years at the physical-fitness facility of a large health center. Three days a week, I do 30 minutes of step aerobics and 30 minutes of hand weights and stretching. The other two days I spend walking, using weight machines and the exercycle.

About 10 percent of the time, after aerobics, I have a drop in blood pressure, a feeling of fatigue and slight dizziness. A check of my blood pressure shows something in the neighborhood of 80/40. After a bit of rest and hydration, it returns to normal.

I am concerned about this and wonder if it is serious. What should I do? – N.B.

I am concerned about this, too. You should see your doctor for a prompt examination. Your heart might not be able to take such grueling exercise, and the drop in blood pressure could be a signal that all is not well.

Or it could be nothing more than dehydration during exercise. If all checks out well with your doctor, then drink during your exercise sessions. It might be better for you to drink sports drinks that replenish lost minerals as well as fluid.

DEAR DR. DONOHUE: I’m moving to a complex with a fitness center. It has a hot tub, a steam room and a sauna. Do these provide any health benefits, or are they just “feel good” activities? – R.T.

There’s something to be said about “feel good” activities. However, in addition, hot tubs, steam rooms and saunas relax stiff joints and tight muscles. They increase blood flow to muscles and skin, and that can speed recovery from exercise. They relieve pain. Enjoy them.

DEAR DR. DONOHUE: A friend of mine has Addison’s disease. Her other friends and I know nothing about it. Does it threaten her life? – B.K.

Addison’s disease threatens life only if it’s not treated. With treatment, people lead long, active and healthy lives. President John F. Kennedy was rumored to have had it.

The adrenal glands figure greatly in blood pressure control and in conserving body potassium and sodium. In Addison’s disease, these glands don’t make any or enough of their hormones to carry out these important functions. Treatment is straightforward – supply the missing hormones in pills.

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

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