DEAR DR. DONOHUE: I am a 23-year-old woman, on my own, in good health except for the fact that I fainted twice in the past month. I could tell the faints were coming on because I broke out in a sweat and felt sick to my stomach. Both times they happened at work when the air conditioning broke down. Should I see a doctor about this? – R.H.

ANSWER: There are many causes of fainting, but the mechanism involved is the same for all. An insufficient amount of blood gets to the brain.

In the common faint, called neurocardiogenic syncope (SIN-koe-pea) or vasovagal syncope, just prior to fainting, a person becomes lightheaded, might be nauseated, can break out in a sweat and then falls to the floor. Fear, a too-hot environment, emotional stress and fasting are some of the situations that bring on a faint.

These circumstances set in motion a train of events that include pooling of blood in the legs and a reflex slowing of the heart – the exact opposite of what should happen. The two work hand in hand to deprive the brain of its blood supply. Without sufficient blood, the brain causes the body to crumple to the ground, a first-aid tactic. In the horizontal position, blood gets back into the circulation, the heart speeds up, and the brain receives its normal blood allotment. This kind of faint almost never indicates any serious underlying problem.

Faints that come about because of a heart-related illness are a much more serious story. Heart valve disease, abnormal heart rhythms, inherited heart disorders and faulty heart wiring can bring about a sudden shortage of blood supply to the brain and a faint. Faints of this nature require in-depth investigation.

Yes, see a doctor. With pointed questions and a physical examination, a doctor can rule out the serious causes of faints. The doctor might have to do a few in-office tests to arrive at that conclusion – an ECG, for example – but it can usually be obtained without difficulty.

DEAR DR. DONOHUE: Last month, I bled from the rectum. I went to the ER, and from there I was admitted to the hospital. The diagnosis was ischemic colitis. I have been discharged without medicines and without any special instructions. I am not clear about this. Should I be doing something? Will it come back? – R.A.

ANSWER: “Ischemia” (is-KEY-me-uh) is a popular medical word used for many conditions. It means a cutoff of the normal blood supply. You had a cutoff of the blood supply to part of your colon (large intestine) – ischemic colitis. The affected colon lining and part of the colon wall died, and bleeding resulted.

In most cases, the process resolves on its own in a day or two, and healing takes place in the next two weeks.

For a few people, the process is much more involved, and the consequences can be dire.

What causes this is often inexplicable. There is nothing special for you to do. When a first episode is mild, as I take it yours was, the chances of recurrence are not great. I realize this is not much for you to hang your hat on, but you can take solace in the statistics that say your future ought to be bright.

There is a similar intestinal disease called mesenteric ischemia, which is a bigger problem and a different story.

DEAR DR. DONOHUE: Is it true that an egg eaten soon after it is laid has little cholesterol? While on this subject, how about telling me how many eggs a person can eat? I love them. – J.J.

ANSWER: As soon as it is laid, an egg has all the cholesterol it is ever going to have — 215 mg.

It’s advisable to keep the daily cholesterol limit at 300 mg. If a person is on a strict low-cholesterol diet, one or two eggs a week are enough. For most others, a daily egg doesn’t raise their cholesterol levels so very much and is permitted. Fatty foods raise blood cholesterol more than do cholesterol-rich foods like eggs.

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.

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