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Old 08-11-2009, 02:08 PM
Yllaria Yllaria is offline
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Why no decaffeinated products before a Chemical Stress Test?

I'm going to have a Persantine/Stress Cardiolite heart test tomorrow. I understand the instructions saying that I shouldn't have caffeine or (long list of medications) for 24 hours before the test. What I don't understand is the instruction not to have 'decaffeinated products'. Under caffeine or decaffeinated products they list coffe, tea, colas, chocolates, frosting, cookies, pies, cocoa, and chocolate milk.

Is it mostly the theobromine in chocolate that they're trying to exclude? Are they assuming that if they let someone drink any cola, that they'll drink the wrong kind by accident? Are they trying to avoid sugars? I'm just not seeing the point in avoiding 'decaffeinated' things. Heck, the average piece of fried chicken has no caffeine. It would be about equally decaffeinated compared to, say, a sugar cookie.

If the instructions were better written, what would they be telling me to avoid? Fo the record, I'm drinking wate and eating meats and vegetables. It seems safest.
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Old 08-11-2009, 02:58 PM
Yllaria Yllaria is offline
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Bump.
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Old 08-11-2009, 03:04 PM
dracoi dracoi is offline
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Decaf doesn't mean no caffeine, it means low caffeine. A cup of regular coffee probably has 100 mg of caffeine, but a decaf cup still has 5 mg.

This is why I always crack up when people say they can't have chocolate for desert because of the caffeine, but then they order a decaf coffee to go with the ice cream. The decaf coffee has more caffeine than the chocolate would have.

I've seen research that suggests 10-20 mg of caffeine is actually the most effective dose - you get a noticeable stimulant effect without any of the negative side effects you see at a higher dose. As a result, even a small dose of caffeine could affect the test you're talking about.
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Old 08-11-2009, 03:20 PM
Demo Demo is offline
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More specifically, the xanthine-based compounds in caffeine, theophylline and theobromine, inherent in even "decaffeinated" foods (as dracoi mentions) antagonistically compete with Adenosine receptors in the body. Persantine (dipyridamole) works by prolonging the effect of endogenous Adenosine in the body, causing vasodilation and hyperemia (mimicking exercise). If the Adenosine receptors are blocked by methylxanthines then ischemic defects in your study might not show up. Check out Tech Tips and click on the link at the top of the page, "Methylxanthines and Pharmacologic Stress Testing".
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