The Effects of Blood Loss on BUN

Studies by Captain I.J. Greenblatt of the US Army were published in 1946. Participants underwent phlebotomy and had either 580 or 800 mLs of their own blood drawn. The BUN didn't increase that much with 580 cc's of blood removed and ingested, but it did increase with 800. But if you compare it to the sort of changes seen in the shift studies, the loss of blood didn't seem to exaggerate the rise in BUN. That was not necessary to see an increase. You just needed to put the blood into the person's stomach.