# I don't know my own blood type. **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [May 12, 2006, 8:54pm UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569 "2006-05-12T20:54:11Z")\ **Posts on this page:** 10\ **Page:** 4
**Author:** ![Antigen](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Antigen](https://boards.straightdope.com/u/Antigen)\ **Post date:** [May 17, 2006, 1:30am UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569/61 "2006-05-17T01:30:21Z")
> [@melondeca](#): > > What would happen if someone were to receive a transfusion of the wrong blood type? I’ll do my best to explain. Being type A or B essentially means you have either the A substance or the B substance on your red blood cells. Type AB has a bit of both, and Type O has neither. Now, our bodies like to defend against foreigners, and so they make antibodies against things that aren’t recognized as self. Usually you need to be exposed to something first, like when you get a virus, but in the case of the blood substances, you’ve _already_ got antibodies in your blood against the substances that aren’t on your cells. When you get transfused with cells that have a different substance on them (you’re Type A, and you get Type B cells, for example), your antibodies will bind onto them and destroy the cells pretty quickly. This process of cells being destroyed is called hemolysis, and it’s a very bad thing. That’s why Type AB can get any type of blood, and why Type O can only get Type O. A transfusion reaction from mismatched blood will cause fever and chills, a drop in blood pressure, and renal damage from all the hemoglobin that’s floating around in the plasma when it should be inside red cells. It can also cause bleeding and micro-clotting in the blood vessels, which can kill the patient. Which is why a lab will never take your word about your blood type. Even if you were in the hospital last week for blood transfusions. Even if you come in every week and they know you well and ask how your kids are doing when they see you. Before giving you anything, they will re-check your blood type and they will do a cross-match with the donor blood to make sure nothing bad will happen. ---
**Author:** ![Pushkin](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@Pushkin](https://boards.straightdope.com/u/Pushkin)\ **Post date:** [May 17, 2006, 8:35am UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569/62 "2006-05-17T08:35:53Z")
> [@irishgirl](#): > > So, in theory your little one could be any of the above (but A+ is most likely). Cool, thanks, the benefits of medical training on the SD message board 🙂 ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [May 17, 2006, 12:29pm UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569/63 "2006-05-17T12:29:16Z")
AB+, & occasional Donor. ---
**Author:** ![melondeca](https://avatars.discourse-cdn.com/v4/letter/m/b5a626/32.png) [@melondeca](https://boards.straightdope.com/u/melondeca)\ **Post date:** [May 17, 2006, 12:52pm UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569/64 "2006-05-17T12:52:28Z")
Thanks, **Antigen** , for that very clear and concise explanation. I think I had heard that before but didn’t understand at the time. ---
**Author:** ![Risha](https://avatars.discourse-cdn.com/v4/letter/r/5fc32e/32.png) [@Risha](https://boards.straightdope.com/u/Risha)\ **Post date:** [May 17, 2006, 4:51pm UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569/65 "2006-05-17T16:51:29Z")
Huh, so _that’s_ what that little “CMV -” statement means on my blood donor card. I never even stopped to wonder about it before. Seems like there’s an awful lot of us A+ CMV- folks around here. ---
**Author:** ![Strinka](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/strinka/32/512_2.png) [@Strinka](https://boards.straightdope.com/u/Strinka)\ **Post date:** [May 17, 2006, 5:28pm UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569/66 "2006-05-17T17:28:05Z")
No one in the world knows my blood type. I wasn’t born in a hospital, so it wasn’t tested right away. I’ve never had a horrible accident or something that I needed a transfusion for. And I can’t give blood yet. ---
**Author:** ![Little\_Plastic\_Ninja](https://avatars.discourse-cdn.com/v4/letter/l/f07891/32.png) [@Little\_Plastic\_Ninja](https://boards.straightdope.com/u/Little_Plastic_Ninja)\ **Post date:** [May 17, 2006, 6:25pm UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569/67 "2006-05-17T18:25:12Z")
I don’t know if I’m CMV-. I do know that I’m AB+, which makes it seem rather pointless for me to give blood. I do, of course, but I still don’t feel I’m doing much good considering that anyone who can use my blood can use anyone else’s, too. ☹ Apparently it also means I’m “both outgoing and shy, confident and timid. While responsible, too much responsibility will cause a problem. They are trustworthy and like to help others.” And I always thought I was just weird. 😃 ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [May 17, 2006, 11:56pm UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569/68 "2006-05-17T23:56:59Z")
Another O neg here. I give as often as I can, universal doner and all. Though us O negs really get the shaft. Universal doner, but can only take our own blood. ---
**Author:** ![Antigen](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Antigen](https://boards.straightdope.com/u/Antigen)\ **Post date:** [May 18, 2006, 12:11am UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569/69 "2006-05-18T00:11:07Z")
> [@Little Plastic Ninja](#): > > I don’t know if I’m CMV-. I do know that I’m AB+, which makes it seem rather pointless for me to give blood. I do, of course, but I still don’t feel I’m doing much good considering that anyone who can use my blood can use anyone else’s, too. ☹ Well, if we’re talking whole blood, you’re right - anyone who can use your red cells could use any others too. But your plasma (the liquid part left over when we spin the blood to separate it) is valuable. Anyone of any blood type can use your plasma, because you don’t have any antibodies in it against the A and the B substances. Blood donations produce more than just bags of whole blood. The blood gets spun down to get red cells to treat anemias, platelets to help clotting, and plasma, which contains clotting factors too. Not only that, but if your AB blood is available for a transfusion to an AB person, it means that the A or B or O unit that would have been used instead goes to someone else. So keep giving! ---
**Author:** ![kiz](https://avatars.discourse-cdn.com/v4/letter/k/7feea3/32.png) [@kiz](https://boards.straightdope.com/u/kiz)\ **Post date:** [May 18, 2006, 2:58am UTC](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569/70 "2006-05-18T02:58:58Z")
> [@KayElCee](#): > > Better not to know, than to think you know and be wrong. My mother had always told me I had type O blood. A pre-surgery screening in my early twenties revealed that I am actually A (positive). Seems dear old Mom had gotten the idea that children always have the same blood type as their mothers. She never even mentioned what she thought my Rh factor was. Same here. I’m a B positive. Found out through a Red Cross donation a few years ago. [Previous page](https://boards.straightdope.com/t/i-dont-know-my-own-blood-type/356569.md?page=3)