570 



ADVENTURES IX RADIOISOTOPE RESEARCH 



Our results, based on an entirely different method, support the conclu- 

 sion drawn by Whipple and his colleagues and by Stead and Ebert. 

 We can account for the discrepancy between the blood volume obtained 

 from the corpuscle {^^F) volume and the plasma (dye) volume and the 

 corpuscle (^^P) volume and the hematocrit value, respectively, by assum- 

 ing that the red corpuscle content of the blood samples is about 18 per 

 cent higher than the average corpuscle content of the circulating blood. 



Blood volume 



A correct figure of the blood volume is obtained if we add to the 

 corpuscle volume supplied by the ^sp method, the plasma volume found 

 with the dye method (cf. Table 7). This procedure is independent of the 

 hematocrit figure though based on the assumption that the dye method 

 supplies us with a correct value for the total plasma volume. 



Table 7. — Blood Volume 



If we determine the blood volume by the dye volume, i. e. if we cal- 

 culate the blood volume from the plasma volume and the hematocrit 

 figure, we get a value which obviously is too high. As the corpuscle 

 content of the total circulating blood is lower than the corpuscle content 

 of the blood sample used in obtaining the hematocrit figure, we overesti- 

 mate the corpuscle volume and, consequently, also the blood volume. 

 This may be seen from the following example. Let us assume the hema- 

 tocrit figure to be 50. If we then add to the plasma volume, 50, an equal 

 corpuscle volume, we obtain a blood volume figure = 100. In view of 

 the fact that the corpuscle content of the circulating blood is about 18 

 per cent lower than the corpuscle content of the sample secured for 

 hematocrit determination, we should add to 50 (plasma volume) 0.82x50 

 (corpuscle volume) and, thus, find 91 for the blood volume. Consequently, 



