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Semi-related question: is the reason smaller people can't donate smaller quantities of blood that transfusion volumes are completely standardized and odd quanti

by majos 8y ago

Semi-related question: is the reason smaller people can't donate smaller quantities of blood that transfusion volumes are completely standardized and odd quantities of blood not practically usable? I ask as someone who's never been close to passing the (apparently universal in the US) 115lb threshold and maybe never will.

projektfu 8y ago
The bags contain a specific amount of anticoagulant and require 450ml blood. There's about 90ml blood per kg body weight, so a 50kg person has 4500ml. It's safe to donate 10%. The cutoff in the US is actually 110lbs (50kg).
- ken 8y ago
  The exact weight requirement varies. At my blood center, for the kind of donations I do, it's actually 114 lbs, for some reason.
  - jdietrich 8y ago
    I'd guess that the extra 4lbs is a safety margin for scale accuracy and the weight of clothing.
    - ken 8y ago
      I'm not sure. Curiously, some types of donation (whole, and double-red apheresis) have a minimum of 110 pounds here, while others (apheresis platelets, plasma) have a minimum of 114 pounds. I'd think if they were worried about scale accuracy or clothing weight, the same safety margin would apply to all donation types -- or at least all apheresis donations.
wyldfire 8y ago
It's because the preservatives in the bag intended to receive your blood only work correctly if they're in the right proportion. They're included presuming a full donation.
- ken 8y ago
  So when the donation is aborted (e.g., the needle hits a valve or skin plug) and they only get part of a unit, but say the partial donation can still be used for research, how does that work? Do researchers not care if the blood is extra-anti-coagulated?
  - wyldfire 8y ago
    Last time I gave a partial donation I was told it would be unused. It would be nice if they could deliver the blood to researchers but there might be challenges regarding the chain of custody, or donor history/privacy. Partial donations are probably rare enough not to try overcoming those challenges.

by majos 8y ago

projektfu 8y ago

The bags contain a specific amount of anticoagulant and require 450ml blood. There's about 90ml blood per kg body weight, so a 50kg person has 4500ml. It's safe to donate 10%. The cutoff in the US is actually 110lbs (50kg).

ken 8y ago
The exact weight requirement varies. At my blood center, for the kind of donations I do, it's actually 114 lbs, for some reason.
- jdietrich 8y ago
  I'd guess that the extra 4lbs is a safety margin for scale accuracy and the weight of clothing.
  - ken 8y ago
    I'm not sure. Curiously, some types of donation (whole, and double-red apheresis) have a minimum of 110 pounds here, while others (apheresis platelets, plasma) have a minimum of 114 pounds. I'd think if they were worried about scale accuracy or clothing weight, the same safety margin would apply to all donation types -- or at least all apheresis donations.

wyldfire 8y ago

It's because the preservatives in the bag intended to receive your blood only work correctly if they're in the right proportion. They're included presuming a full donation.

ken 8y ago
So when the donation is aborted (e.g., the needle hits a valve or skin plug) and they only get part of a unit, but say the partial donation can still be used for research, how does that work? Do researchers not care if the blood is extra-anti-coagulated?
- wyldfire 8y ago
  Last time I gave a partial donation I was told it would be unused. It would be nice if they could deliver the blood to researchers but there might be challenges regarding the chain of custody, or donor history/privacy. Partial donations are probably rare enough not to try overcoming those challenges.