PLASMA PROTHROMBIN LEVELS IN VARIOUS VERTEBRATES

Abstract

The plasma prothrombin levels are far higher in mammals than in the lower vertebrates. In dogfish plasma it is only 8% as high as in plasma of the dog. In the plasma of bony fishes, reptiles, and fowls, the values rise progressively, broadly according to the position in the evolutionary scale. In human plasma the prothrombin level is slightly lower than in dog plasma, and in guinea-pig plasma the level is lower still. Certain mammals, including man, show sluggish conversion of prothrombin into thrombin. Because of this sluggish conversion, these spp. are handicapped in the control of hemorrhage.