# What color is blood? **URL:** \ **Category:** Factual Questions\ **Created:** [June 22, 2006, 4:43am UTC](https://boards.straightdope.com/t/what-color-is-blood/361677 "2006-06-22T04:43:45Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![StarvingButStrong](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/starvingbutstrong/32/335_2.png) [@StarvingButStrong](https://boards.straightdope.com/u/StarvingButStrong)\ **Post date:** [June 23, 2006, 3:36am UTC](https://boards.straightdope.com/t/what-color-is-blood/361677/21 "2006-06-23T03:36:32Z")
Thank you for the informative replied, **KarlGauss** and \*\*CC \*\* – though I’m sad that isn’t a better way to do it. Actually - why do they need SO MUCH blood for these tests, anyway? If they can do DNA matching from single drop of dried old blood, surely they could do tests on a pinprick’s worth of blood, you’d think. More joyous news: they want mom to go on Coumadin, meaning a blood test EVERY SINGLE MONTH! \ I wonder if I could manage to get that director to do the draw each time? I mean BEFORE mom has been tortured by the beginner and intermediate level people. ---
**Author:** ![Sampiro](https://avatars.discourse-cdn.com/v4/letter/s/2acd7d/32.png) [@Sampiro](https://boards.straightdope.com/u/Sampiro)\ **Post date:** [June 23, 2006, 3:43am UTC](https://boards.straightdope.com/t/what-color-is-blood/361677/22 "2006-06-23T03:43:24Z")
All of this, of course, is assuming you’re human and not in fact a horseshoe crab, in which case your blood is [blue](http://www.floridamarine.org/gallery/image_details.asp?id=19668) (and _extremely_ valuable- hundreds and sometimes thousands of dollars per ounce for it’s uses in medical testing, so if you ever have a horseshoe crab insist on staying over for a few days, try to bleed him at night to pay for his long distance bill). ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [June 23, 2006, 3:54am UTC](https://boards.straightdope.com/t/what-color-is-blood/361677/23 "2006-06-23T03:54:08Z")
> [@StarvingButStrong](#): > > More joyous news: they want mom to go on Coumadin, meaning a blood test EVERY SINGLE MONTH! Sorry to say, but I bet she’s gonna need tests a lot more frequently than that, especially in the first week or two. With coumadin therapy, it’s necessary to test the blood in order to determine the correct dose. Once the proper dose has been identified in this way, though, the frequency of blood tests can be reduced. Just as an aside, the blood test required to assess Coumadin therapy is called the **INR** (standing for **I** nternational **N** ormalized **R** atio). There’s big money to be had in developing an effective blood thinner that doesn’t require ongoing monitoring. Recently, that drug seemed to arrived. Called ximelagatran, it’s as least as good as Coumadin. Unfortunately, it led to a very high rate of liver damage and will likely never be widely used. The search continues . . . ---
**Author:** ![Sampiro](https://avatars.discourse-cdn.com/v4/letter/s/2acd7d/32.png) [@Sampiro](https://boards.straightdope.com/u/Sampiro)\ **Post date:** [June 23, 2006, 4:14am UTC](https://boards.straightdope.com/t/what-color-is-blood/361677/24 "2006-06-23T04:14:12Z")
My mother’s INR is tested weekly and is wildly erratic. Between 2-3 is considered ideal for her and it’s risen as high as 7 and sunk as low as .5 the same three days. Weird. Of course on coumaden you cannot eat salad or any other green leafy vegetable. ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [June 23, 2006, 4:58am UTC](https://boards.straightdope.com/t/what-color-is-blood/361677/25 "2006-06-23T04:58:31Z")
> [@Sampiro](#): > > Of course on coumaden you cannot eat salad or any other green leafy vegetable. Well, not really. You’re right that eating **large** quantities of leafy green vegies, in particular, can lower coumadin’s effectiveness. But that shouldn’t stop a person from eating reasonable amounts of salad. And, I suppose that if someone really, really likes their ‘greens’, that’s OK so long as they keep their intake relatively constant. In that circumstance, with a relatively constant amount of those vegetables in the diet, the INR will indicate whether their dosage of coumadin is appropriate. In other words, a person who eats lots of green vegetables may need a higher dose of coumadin, but that’s OK. The key thing is for them not to suddenly change their intake. ---
**Author:** ![Mathochist](https://avatars.discourse-cdn.com/v4/letter/m/c89c15/32.png) [@Mathochist](https://boards.straightdope.com/u/Mathochist)\ **Post date:** [June 23, 2006, 6:37am UTC](https://boards.straightdope.com/t/what-color-is-blood/361677/26 "2006-06-23T06:37:16Z")
> [@KarlGauss](#): > > Well, not really. You’re right that eating **large** quantities of leafy green vegies, in particular, can lower coumadin’s effectiveness. But that shouldn’t stop a person from eating reasonable amounts of salad. And, I suppose that if someone really, really likes their ‘greens’, that’s OK so long as they keep their intake relatively constant. In that circumstance, with a relatively constant amount of those vegetables in the diet, the INR will indicate whether their dosage of coumadin is appropriate. In other words, a person who eats lots of green vegetables may need a higher dose of coumadin, but that’s OK. The key thing is for them not to suddenly change their intake. I’m not sure what exactly my father is on, but the same thing applies. A certain amount of leafy vegetables for the vitamin K’s effect on blood thickness. Then he fell and hurt his side, so took some Tylenol, which meant adjusting the salad intake to compensate… Just gimme a nice train to the face at 40. ---
**Author:** ![Snooooopy](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@Snooooopy](https://boards.straightdope.com/u/Snooooopy)\ **Post date:** [June 23, 2006, 7:34am UTC](https://boards.straightdope.com/t/what-color-is-blood/361677/27 "2006-06-23T07:34:04Z")
> [@StarvingButStrong](#): > > Thank you for the informative replied, **KarlGauss** and \*\*CC \*\* – though I’m sad that isn’t a better way to do it. > > Actually - why do they need SO MUCH blood for these tests, anyway? Vampire lab techs. ---
**Author:** ![MaryEFoo](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@MaryEFoo](https://boards.straightdope.com/u/MaryEFoo)\ **Post date:** [June 23, 2006, 8:05am UTC](https://boards.straightdope.com/t/what-color-is-blood/361677/28 "2006-06-23T08:05:26Z")
**StarvingButStrong** , a nurse told me once that if you aren’t well hydrated, the veins are much harder to get into. I hope this makes your next trip easier. (IANAD, please do not hesitate to verify this item with actual medical personnel!) ---
**Author:** ![gabriela](https://avatars.discourse-cdn.com/v4/letter/g/db5fbb/32.png) [@gabriela](https://boards.straightdope.com/u/gabriela)\ **Post date:** [June 23, 2006, 10:09am UTC](https://boards.straightdope.com/t/what-color-is-blood/361677/29 "2006-06-23T10:09:28Z")
> [@CC](#): > > I’m sorry, and this may be total heresy, but I gotta call \*partial \* bullshit on a Cecil column, and although it’s not written by the Man, it was sanctioned by him. If that explanation were correct, and it is partially correct, because the phenomenon he reports on is, in fact, observable, what accounts for the fact that an animal blood vessel, mammal or bird, is blue when we dissect it? Clean a chicken breast before cooking it. Don’t you see BLUE veins? A steak? BLUE veins. No blood in them. No light penetrating skin. What’s the explanation? I’d suggest that the tissue has its own coloration. Veins are blue. That’s the preferred explanation. It’s confusing to trot out mumbo jumbo about light absorbing, diffusing, etc. etc. While that may be part of the explanation (and I’m not convinced it’s a significant part of the answer), a perfectly good enough part of the answer is the reason that veins look blue is that…they’re blue. I like this post because it is based on observation. It is essentially scientific in its attitude and in its skepticism. However, I have a different explanation for why veins are blue, and it doesn’t rely on being unable to tell veins apart from arteries. Hey, **CC** , in dead people when I first open them up to look inside, the large veins are blue, but the arteries have that pinky-chalky-white color of all human connective tissue. When I suck the blood out of a vein (with a needle! With a needle!) to put it in tubes, the vein turns white. The blood is dark red when i get it out, but the vein has turned white. So it really isn’t the color of the vein wall. That’s an observation for you so you won’t have to call bullshit on the deductions. So why is the artery whitish, and the vein blue until I take the blood out, when it’s white? Because you can sort of see the blood through the thin wall of the vein. Artery walls are so thick that you can’t see through them. Vein walls are sort of translucent. So why does red blood, which is clearly dark red when I get it out of the vein, look blue through the vein wall? Here I’m getting into deep waters. So to speak. The ocean looks blue (on a sunny day), but the water is clear. The bladder when it’s very distended sometimes looks blue, but the urine is yellow to clear. Why is it that large volumes of fluid of one color may have a different color from small volumes? Why do fluids of one color seen through a translucent but not transparent membrane have a different color? Physics people, the answers? ---
**Author:** ![audiobottle](https://avatars.discourse-cdn.com/v4/letter/a/bc8723/32.png) [@audiobottle](https://boards.straightdope.com/u/audiobottle)\ **Post date:** [June 23, 2006, 12:29pm UTC](https://boards.straightdope.com/t/what-color-is-blood/361677/30 "2006-06-23T12:29:22Z")
> [@Snooooopy](#): > > Vampire lab techs. > [@gabriela](#): > > When I suck the blood out of a vein … Dr. Acula, perhaps? [Previous page](https://boards.straightdope.com/t/what-color-is-blood/361677.md?page=1)