Does the feast before the fast matter?
November 22, 2011 1:00 PM   Subscribe

Is it stupid for me to get a cholesterol blood test the Friday morning after Thanksgiving? My doctor instructed me to fast for at least 7 hours prior to the test, but I just read something else online that said I should fast for more like 14 hours, and not drink alcohol for 48 hours prior to getting the test.
posted by queensissy to Health & Fitness (10 answers total) 1 user marked this as a favorite
Push it out until Monday if you can. There's a better chance of your blood not being 35% gravy on Monday as it would be on Friday.
posted by jerseygirl at 1:03 PM on November 22, 2011 [3 favorites]

Yes. Reschedule.
posted by The Michael The at 1:03 PM on November 22, 2011

Totally reschedule.
posted by guster4lovers at 1:03 PM on November 22, 2011

Just call your doctor and ask him to reiterate the 7 hour rule and ask him about alcohol. If not, it's not like Thanksgiving is a ritual where you inject lard into your veins. It's just a big meal, and probably not any bigger than one you'd have before a fast anyway.
posted by thewumpusisdead at 1:20 PM on November 22, 2011

Yes, put it off. I once had blood work done two days after having a bit of a binge with leftover Halloween candy. My numbers were so out of whack, my doctor thought the lab had made a mistake. A couple weeks later my do-over blood work reverted to my normal, healthy, non-candy blowout numbers.
posted by Elsie at 1:22 PM on November 22, 2011

Here are some general guidelines, I don't know how accurate they are.
posted by mareli at 1:26 PM on November 22, 2011's not like Thanksgiving is a ritual where you inject lard into your veins.

I think you're doing Thanksgiving wrong, thewumpus. Rescheduling is in order. I just did one of these, and doc said 12-hour fast was minimum.
posted by ourobouros at 1:37 PM on November 22, 2011 [2 favorites]

I'm not specifically sure about cholestoral testing, but certainly these things can show abnormal results if you've eaten the wrong thing too closely to the test.

Example: eating a can of these on the same day that you get a blood pressure test. I'm pretty sure that a serving size is less than a full can, and it has more than 100% of your daily recommended intake of sodium (of course, this wasn't realized until several days AFTER the tes).

The doctor then demanded a full month of daily blood pressure monitoring just to make sure that the result really was an anomaly.
posted by asnider at 1:40 PM on November 22, 2011

Yes, reschedule.
posted by dawkins_7 at 2:35 PM on November 22, 2011

(An outpatient lab is open Friday morning? I hope those phlebotomists are getting holiday pay.)
The link that mareli posted is what I've heard from endocrinologists - lipoprotein levels aren't responsive to short-term changes, but the other components of the lipids panel can be, so you should schedule the test at a time when you're eating and drinking as you usually do, and fast overnight before the test. I've not been told to abstain from alcohol beforehand but it makes sense - lipid metabolism is chiefly hepatic, alcohol metabolism generally takes precedence over other hepatic functions, so if you drink more heavily than usual, you'll throw off your serum lipid levels.
posted by gingerest at 4:18 PM on November 22, 2011

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