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Medical Forum / General / General / May 2005Vitamins and Colonoscopy
I'm scheduled for my "over 50" colonoscopy screening later this month. On the list of preparation do's and don'ts, there is the admonition not to take, for a week before the procedure, aspirin & related products, iron supplements, and "all vitamins". I understand the reasons for the aspirin and iron; but what is it about vitamins in general? I understand that only "some" vitamins are a problem, but the response I got from my gastroenterologist's office is that they would rather not give a specific list so as "to keep things less complicated when instructing our patients". I don't mind complicated -- I can work out how to avoid the problem ones. I am particularly interested in Vitamin C, which I've been taking regularly for over 30 years and would rather not discontinue for a week, though I'm sure I'd get by! Thanks in advance for any information or appropriate links. -- Steve Hehr To send me email, replace the "OUT" in my address with its opposite. > I'm scheduled for my "over 50" colonoscopy screening later this month. > On the list of preparation do's and don'ts, there is the admonition [quoted text clipped - 11 lines] > taking regularly for over 30 years and would rather not discontinue > for a week, though I'm sure I'd get by! Yes, stopping your vitamin C would just mean that you'd be peeing out less excess vitamin C for a week. There's nothing wrong with vitamins before a colonoscopy, but vitamins that contain iron, as many do, may make for some black stool in there that could be confused with upper GI bleeding (melena) at the time of the colonoscopy and samples can cause false positives for occult blood. Such a huge variety of vitamin preparations out there that I'm sure it's easier for them to just say "stop all vitamins" rather than "stop all vitamins that contain iron or anything else that will screw up your colonscopy". If I were having a colonoscopy and felt Vitamin C was somehow important to my health, I'd just keep taking the Vitamin C. HMc >>There's nothing wrong with vitamins before a colonoscopy, but vitamins that contain iron, as many do, may make for some black stool in there that could be confused with upper GI bleeding (melena) at the time of the colonoscopy and samples can cause false positives for occult blood. << COMMENT: Not if you're using guaiac reaction cards, it won't. That's an urban medical myth. Those cards require the catalytic properties of heme-iron, and the only false positives they return is if you're eating lots of stuff with heme iron. Like steak tartar and wasabi sauce (all that green heme-containing horseradish peroxidase is why wasabi is exactly snot green, and why shot is green too, as a result of a similar enzyme in eosinophils), etc. Eating iron supplments (which contain ferrous iron) won't cause false positive stool occult blood tests, although it *will* produce a somewhat dark stool. This is hard to confuse with melena for those who have seen and smelled real melena, but in any case, the guaiac test tells the truth of the tale. Large amounts of vitamin C can cause a false NEGATIVE on guaiac, since they inhibit the oxidation which is at the center of that test (and which happens when you put the hydrogen peroxide on the little card). But that's only for stool with so little blood you wouldn't see it it anyway. Melanotic stool will be guaiac positive no matter how much vitamin C you take. The true reason why GI docs don't like vitamin pills is they hate to see the undigested things in a colonoscope.... SBH >>>There's nothing wrong with vitamins before a colonoscopy, but > vitamins that [quoted text clipped - 27 lines] > The true reason why GI docs don't like vitamin pills is they hate to > see the undigested things in a colonoscope.... Dark stool, such as might occur with iron supplements, can cause a false postive interpretation based on distingishing the dark stool from the blue color that appears on the card. The vitamin C issue is an interesting lab experiment, but has no practical application. I respect your experience in this arena, Steve. I doubt that it exceeds mine. HMc I'm being investigated, treated and followed and followed for: -calcification of coronary artery -erythrocytosis -proteinuria -colonic polyps -diabetic, controlled well with insulin Colonic polyps were removed by colonoscopy (twice/one year apart), as well there was newly discovered blood in urine. Some of the larger polyps were maligering (-:. Proteinuria has been observed since childhood, is very slight, and has remained the same pretty much over time. Had experienced severe anemia before first colonoscopy, recovered not badly, but still suffering extreme fatigue although relevant bloodwork post colonoscopy and after period of recovery showed Fe normal and hemaglobin slightly above upper range normal. Follow-up blood density test indicated high RBC concentration, likely due to low plasma level. Q- 1-What could be the cause of ongoing fatigue? 2-Are any of the above conditions related in any way - such as combining to produce fatigue? 3-What is the protocol for treating the coronary artery condition. Prognosis? Note- I do not experience any chest pains or shortness of breath. Thanks. I dunno, Howard. It's hard to tell who's telling who's granny how to suck eggs. Unless you do digital exams for a living? I don't know how many thousands of guaiac's I've done. Blue is BLUE. It doesn't look in the least like iron-darkish-green. And if you're smearing so thickly you're seeing *any* color but faint-brown or yellowish brown, you're smearing it too thickly. [Smearing it on a bit thickly here} Humbly Yrs, SBH >I dunno, Howard. It's hard to tell who's telling who's granny how to > suck eggs. Unless you do digital exams for a living? I don't know how [quoted text clipped - 6 lines] > > Humbly Yrs, Well, actually I was referring to colonoscopy and the visual appearance of iron-containing stool rather than the appearance on a developed guaiac card. Perhaps I overstated my case? Let me restate after trying to tame my ego a little.... I see that you're correct - iron may cause a false-positive guaiac in vitro, but oral iron does not in vivo. Fortunately, DRE for screening isn't a routine part of my practice and my basis for that exam is palpation rather than Hemoccult. Patient's are referred to me pre-guaiac'ed. From a practical standpoint, my point was that at colonoscopy, from a visual standpoint, iron or iron-containing medications/vitamins could conceivably be confused with acid hematin and forms the basis for trying to exclude such compounds as part of a colonoscopy prep. On that, I stand firm as the rock of Gibralter...unless you have something else I should know...? HMc >>I see that you're correct - iron may cause a false-positive guaiac in vitro, but oral iron does not in vivo.<< COMMENT: Yep. There are some conditions where iron ions CAN do the trick, but not at the pH of the colon, where they're all precipitated out. So in practice you don't see it. Maybe if you were guaiacing NG tube return you might see a false positive from iron pills, but not with stool. >>Fortunately, DRE for screening isn't a routine part of my practice and my basis for that exam is palpation rather than Hemoccult.<< COMMENT: Mine usually also, of course. Feeling prostates, mostly. But if you get stool, one tends to use it (your patients may be as bad at remembering to mail things as you are_. >>From a practical standpoint, my point was that at colonoscopy, from a visual standpoint, iron or iron-containing medications/vitamins could conceivably be confused with acid hematin and forms the basis for trying to exclude such compounds as part of a colonoscopy prep. On that, I stand firm as the rock of Gibralter...unless you have something else I should know...? << COMMENT: I just wanted to point out that nobody trusts their impression of "acid hematin" from what they see in a colonoscope screen anyway, so what's the point? I think this is one of those things like taking not taking vitamin E before plastic surgery, or with Coumadin, which gets ingrained, and just goes on and on because everybody knows it's so. Sort of like not letting patients even drink water the evening before surgery, not letting them get out of bed for weeks after an MI, and never giving a narcotic to anybody complaining of abdominal pain. These things all seemed reasonable at one time. Now we know better. Some hard and fast rules aren't every hard and fast, and others should not even be rules. Always question. If your patient is taking 365 mg of FeSO4 t.i.d. for iron deficiency anemia (I never give that much, but some docs do), and that's how they come to you for colonoscopy, I can see why some doctors would want them off, since this much will stain everything green, and is irritating to the stomach enough to cause many people to be guaiac pos from REAL blood. But somebody who forgot to not take their Theragram M? Bah. SBH "Sbharris[atsign]ix.netcom.com" < > wasabi sauce (all > that green heme-containing horseradish peroxidase is why wasabi is > exactly snot green Huh? It's coloured with vegetable dye. Fresh wasabi is slightly yellow. Japanese restaurants use the premix stuff because it's a pain to make and it doesn't really taste any different. (Just confirmed this with the much celebrated Mr. Mori of Toshi in Toronto; where I worship at least three times a week > The true reason why GI docs don't like vitamin pills is they hate to > see the undigested things in a colonoscope.... Yes. Follow the purging directions exactly. My guy actually compliments those who do. moo > wasabi sauce (all > that green heme-containing horseradish peroxidase is why wasabi is > exactly snot green >>Huh? It's coloured with vegetable dye. Fresh wasabi is slightly yellow. << COMMENT: Ah so desu ka? I learn something! Okay, replace what I said by "exactly snot yellow..." SBH >>I'm scheduled for my "over 50" colonoscopy screening later this month. >>On the list of preparation do's and don'ts, there is the admonition [quoted text clipped - 27 lines] > > HMc Thanks for the helpful answer to the question I hadn't thought to ask (I'm getting a screening colonoscopy next month). Steve  SignatureMark & Steven Bornfeld DDS http://www.dentaltwins.com Brooklyn, NY 718-258-5001 "Mark & Steven Bornfeld" <bornfeldmung@ >> There's nothing wrong with vitamins before a colonoscopy, but vitamins >> that contain iron, as many do, may make for some black stool in there [quoted text clipped - 12 lines] > Thanks for the helpful answer to the question I hadn't thought to ask (I'm > getting a screening colonoscopy next month). Follow the "cleansing" instructions exactly. Stock up on clear soups. The writer recommends clear fish broth from your local Japanese restaurant. I suggest Next Door Nobu on Hudson St. at Canal (near the Holland Tunnel). (212) 334-4445 Call them a day in advance and have them make a gallon of clear Bonita broth. Godlike. If you cook, it's a good time to bone up on your consomee skills. Don't drive and enjoy the Demoral. le moo |
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