# Will a swallow of Orange Juice ruin a fasting blood test? Kinda need answer fast. **URL:** \ **Category:** In My Humble Opinion\ **Created:** [April 2, 2013, 12:41pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619 "2013-04-02T12:41:47Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![yanceylebeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yanceylebeef/32/12290_2.png) [@yanceylebeef](https://boards.straightdope.com/u/yanceylebeef)\ **Post date:** [April 2, 2013, 12:41pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/1 "2013-04-02T12:41:47Z")
I guess the title says it all. I got up this morning, and without thinking had a swallow of OJ. I have a blood test for kidney function, and a lipid panel. Is that enough to warrant passing on this test and trying again tomorrow? ---
**Author:** ![Athena](https://avatars.discourse-cdn.com/v4/letter/a/35a633/32.png) [@Athena](https://boards.straightdope.com/u/Athena)\ **Post date:** [April 2, 2013, 12:53pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/2 "2013-04-02T12:53:51Z")
I don’t know specifically about those tests, but I do know that a swallow of orange juice would throw off a fasting blood glucose test. Call the lab or your doc and ask, you may very well be warranted to put it off. ---
**Author:** ![yanceylebeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yanceylebeef/32/12290_2.png) [@yanceylebeef](https://boards.straightdope.com/u/yanceylebeef)\ **Post date:** [April 2, 2013, 4:10pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/3 "2013-04-02T16:10:18Z")
Welp, one swallow means it’s not a fast. Sigh. I’ll try again tomorrow. ---
**Author:** ![nonacetone](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nonacetone/32/2819_2.png) [@nonacetone](https://boards.straightdope.com/u/nonacetone)\ **Post date:** [April 2, 2013, 4:22pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/4 "2013-04-02T16:22:14Z")
Yep! Only water before fasting BG test. OJ is full of sugar. You don’t want that. ---
**Author:** ![Shoeless](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/shoeless/32/7099_2.png) [@Shoeless](https://boards.straightdope.com/u/Shoeless)\ **Post date:** [April 2, 2013, 5:23pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/5 "2013-04-02T17:23:35Z")
> [@nonacetone](#): > > Yep! Only water before fasting BG test. OJ is full of sugar. You don’t want that. My doctor allows coffee (black, with no additives) the morning of a fasting blood test. Which is a good thing, otherwise I’d probably never be able to make it in to the doctor’s office! ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [April 2, 2013, 5:28pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/6 "2013-04-02T17:28:31Z")
Tell your doctor. What’s the use of taking the test if the results could be off? ---
**Author:** ![yanceylebeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yanceylebeef/32/12290_2.png) [@yanceylebeef](https://boards.straightdope.com/u/yanceylebeef)\ **Post date:** [April 2, 2013, 5:28pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/7 "2013-04-02T17:28:38Z")
The nurse told me a cup of coffee wouldn’t disqualify me, but it may skew the results slightly. No biggie. Had a nice granola bar for brekkie. ---
**Author:** ![April\_R](https://avatars.discourse-cdn.com/v4/letter/a/3da27b/32.png) [@April\_R](https://boards.straightdope.com/u/April_R)\ **Post date:** [April 2, 2013, 5:44pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/8 "2013-04-02T17:44:06Z")
the granola would throw it off too :smack: ---
**Author:** ![yanceylebeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yanceylebeef/32/12290_2.png) [@yanceylebeef](https://boards.straightdope.com/u/yanceylebeef)\ **Post date:** [April 2, 2013, 5:59pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/9 "2013-04-02T17:59:58Z")
Had the granola after I knew I had already blown the fasting. Now it’s a salad for lunch, cold chinese for dinner, and try again tomorrow. ---
**Author:** ![tdn](https://avatars.discourse-cdn.com/v4/letter/t/94ad74/32.png) [@tdn](https://boards.straightdope.com/u/tdn)\ **Post date:** [April 2, 2013, 6:20pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/10 "2013-04-02T18:20:23Z")
I was on an all clear liquids diet a couple of weeks ago. The instructions said not to drink anything, even water, after 4 hours before the surgery. I woke up a little late so it was more like 3.5 hours before, I had 2 big glasses of water. When I checked in, the nurse asked me if I’d had anything to drink after midnight. Yes, I have! She also asked if my poo was running clear. No, it’s wasn’t. She looked at me like a disappointed schoolmarm. And then let me have the surgery anyway. ---
**Author:** ![Loach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loach/32/350_2.png) [@Loach](https://boards.straightdope.com/u/Loach)\ **Post date:** [April 2, 2013, 7:18pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/11 "2013-04-02T19:18:56Z")
> [@tdn](#): > > I was on an all clear liquids diet a couple of weeks ago. The instructions said not to drink anything, even water, after 4 hours before the surgery. I woke up a little late so it was more like 3.5 hours before, I had 2 big glasses of water. > > When I checked in, the nurse asked me if I’d had anything to drink after midnight. Yes, I have! She also asked if my poo was running clear. No, it’s wasn’t. She looked at me like a disappointed schoolmarm. And then let me have the surgery anyway. How does poo run clear? :dubious: ---
**Author:** ![April\_R](https://avatars.discourse-cdn.com/v4/letter/a/3da27b/32.png) [@April\_R](https://boards.straightdope.com/u/April_R)\ **Post date:** [April 2, 2013, 7:27pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/12 "2013-04-02T19:27:15Z")
> [@Loach](#): > > How does poo run clear? :dubious: drink a full round of [Go Lightly](http://www.healthcentral.com/colon-cancer/h/go-lightly-colonoscopy-drink.html) and you will never ask that question again ☹ ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [April 2, 2013, 8:03pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/13 "2013-04-02T20:03:08Z")
> [@Loach](#): > > How does poo run clear? :dubious: With the laxative/enema regime used to prepare for a colonoscopy, it gets to the point where all that comes out is essentially clear water. ---
**Author:** ![tdn](https://avatars.discourse-cdn.com/v4/letter/t/94ad74/32.png) [@tdn](https://boards.straightdope.com/u/tdn)\ **Post date:** [April 2, 2013, 8:09pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/14 "2013-04-02T20:09:00Z")
> [@Gary\_T](#): > > With the laxative/enema regime used to prepare for a colonoscopy, it gets to the point where all that comes out is essentially clear water. Exactly. But I wouldn’t drink it, even mixed with koolaid. ---
**Author:** ![aruvqan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aruvqan/32/2891_2.png) [@aruvqan](https://boards.straightdope.com/u/aruvqan)\ **Post date:** [April 2, 2013, 11:39pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/15 "2013-04-02T23:39:18Z")
My problem is I get up at 5 am, the earliest any lab opens for bloodwork is 7, so my liver is already cranking out glucose by the time I can get any blood tapped. Sucks for me. ---
**Author:** ![Mama\_Zappa](https://avatars.discourse-cdn.com/v4/letter/m/71e660/32.png) [@Mama\_Zappa](https://boards.straightdope.com/u/Mama_Zappa)\ **Post date:** [April 3, 2013, 1:42pm UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/16 "2013-04-03T13:42:11Z")
> [@aruvqan](#): > > My problem is I get up at 5 am, the earliest any lab opens for bloodwork is 7, so my liver is already cranking out glucose by the time I can get any blood tapped. Sucks for me. Really? I mean, a fasting blood test means “don’t consume calories”, but does it really affect things if you’ve been up for a while? I’ve never heard of that being an issue before. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [April 6, 2013, 7:14am UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/17 "2013-04-06T07:14:01Z")
I’ve went ahead with a blood-glucose test before to avoid the hassle, and everything worked out fine. Granted, my accidental drink was about six hours before, so that might have been less of an issue. I do know that some tests don’t really need absolute fasting, so I hope you checked with your doctor. I know that I’ve told my doctor I didn’t fast (as I get really weak if I do) and all he did was check a box on the form saying I hadn’t been fasting. And, on the results I got, they listed both the normal numbers for fasting and non-fasting. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [April 6, 2013, 7:23am UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/18 "2013-04-06T07:23:34Z")
> [@Shoeless](#): > > My doctor allows coffee (black, with no additives) the morning of a fasting blood test. Which is a good thing, otherwise I’d probably never be able to make it in to the doctor’s office! I had black coffee before a fasting test, and I had to come back the next day. They said nothing but water. ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [April 8, 2013, 8:28am UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/19 "2013-04-08T08:28:42Z")
> [@April\_R](#): > > drink a full round of [Go Lightly](http://www.healthcentral.com/colon-cancer/h/go-lightly-colonoscopy-drink.html) and you will never ask that question again ☹ I thought it was “GoLYTELY”. What I don’t get is, they say eating before a cholesterol test doesn’t affect total cholesterol and HDL results ([Tests and Procedures | livestrong](http://www.livestrong.com/article/443355-what-happens-if-one-eats-before-a-cholesterol-test/)) but it affects LDL. How does it affect LDL and not total cholesterol? ---
**Author:** ![Ximenean](https://avatars.discourse-cdn.com/v4/letter/x/aca169/32.png) [@Ximenean](https://boards.straightdope.com/u/Ximenean)\ **Post date:** [April 8, 2013, 9:22am UTC](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619/20 "2013-04-08T09:22:59Z")
> [@panache45](#): > > I had black coffee before a fasting test, and I had to come back the next day. They said nothing but water. Similarly, I had a Diet Coke the night before. When I told the nurse she sighed and said we had to reschedule it. Nothing at all except water, she said. [Next page](https://boards.straightdope.com/t/will-a-swallow-of-orange-juice-ruin-a-fasting-blood-test-kinda-need-answer-fast/654619.md?page=2)