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Your Good Health: Heatstroke, heat exhaustion two different conditions

Dear Dr. Roach : What is heatstroke? I exercised a lot in the heat yesterday, and today I feel dizzy and nauseated, even though it isn’t as hot as yesterday. L.C. Heatstroke and heat exhaustion have similar names but are different conditions.
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Dr. Keith Roach writes a medical question-and-answer column weekdays.

dr_keith_roach_with_bkg.jpgDear Dr. Roach: What is heatstroke? I exercised a lot in the heat yesterday, and today I feel dizzy and nauseated, even though it isn’t as hot as yesterday.

L.C.

Heatstroke and heat exhaustion have similar names but are different conditions. People who exercise in conditions of high heat and humidity are at risk for heat exhaustion. Symptoms include profuse sweating, dizziness, nausea, muscle cramps and headache. Treatment is to stop exercising, get someplace cool and sip some fluids. Without treatment, heat exhaustion can lead to heatstroke, although you don’t need to exercise to get heatstroke.

The hallmark of heatstroke is a very high body temperature: 103 F (39.4 C). There may not be any sweating at all, and the skin is hot and red. Confusion is a dangerous symptom.

Heatstroke is a medical emergency: call 911. In the emergency room or hospital, we find the fastest way of cooling someone down is room-temperature or warm water sprayed all over a person’s body (no clothes) with immense fans blowing on the moist skin. Immersing a person in cold water is not as effective. The warm water keeps a high degree of blood flow to the skin, allowing the body to cool rapidly. Ice cold water constricts blood vessels, which makes heat transfer less effective. Fluids need to be individualized based on careful patient monitoring.

Dear Dr. Roach: I’m 62 with a family history of coronary artery disease. I have mildly high LDL cholesterol level, and my 10-year risk of heart disease is 26% considering my treated high blood pressure. I was on Crestor, but I read that it can increase the risk of diabetes. I changed to Lipitor, but then read that lipophilic statins increase dementia risk (which runs in my family). Pravastatin is the only hydrophilic statin left — should I switch to that?

M.S.

With your high risk of developing a heart attack or stroke, treatment with a statin is clearly indicated. This should be in addition to lifestyle changes, which are not often enough emphasized. Dietary changes and regular moderate exercise have large benefits in preventing heart disease, in addition to many other benefits.

All statins increase the risk of developing diabetes. The relative risk is estimated to be about 10%. Put another way, treating 1,000 people with high-dose statin would be expected to cause five to 10 new cases of diabetes. It is thought that diabetes will occur in people who have genetic risk for diabetes.

Hydrophilic and lipophilic are terms that refer to a drug’s ability to dissolve. Hydrophilic drugs dissolve in water, while lipophilic drugs are fat-soluble. A new study looking at reports of memory loss associated with statins found that it is more commonly reported in people taking lipophilic statins than hydrophilic statins. In the case of memory loss after statin, switching to a different statin, preferably hydrophilic, is a reasonable strategy, as often this can reverse the memory issue. Simvastatin (Zocor), atorvastatin (Lipitor), lovastatin (Mevacor), fluvastatin (Leschol) and pitavastatin (Livalo) are lipophilic statins. Pravastatin (Pravachol) and rosuvastatin (Crestor) are hydrophilic.

Large studies have shown that neither lipophilic nor hydrophilic statins increase in the risk of developing Alzheimer’s dementia, and some studies have shown a reduction in the risk of developing dementia. I suspect there are some people who have a medication reaction to statins causing memory loss, but statins overall do not hurt and may help prevent dementia, perhaps by preventing small strokes.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu