ANEMIA AND THE SPECIFIC ANEMIAS 301 



ANEMIA AND THE SPECIFIC ANEMIAS" 



The customary although unsatisfactory and unscientific division 

 of the anemias, is into — ■ (a) 'primary, i. e., those in which the anemia 

 seems to depend upon some abnormahty in the blood-forming organs 

 or in the blood itself; and (6) secondare/, embracing anemias the result 

 of some obvious cause, such as hemorrhage, poisoning with blood- 

 destroying poisons, cachexia, etc. In these various forms of anemia 

 certain chemical differences prevail, but they are by no means so strik- 

 ing as arje the histological differences in the formed elements of the 

 blood. ^1 



Secondary Anemias 



As the simplest variety, anemia following a single large hemorrhage 

 may be considered first. 



If loss of blood by hemorrhage is rapid, the effects are naturally 

 much more serious than when the loss is slow. The total quantity of 

 blood in the average adult is estimated at about 3d^3 to ^5 the total 

 body weight (.therefore about 10 to 12 pounds), although this propor- 

 tion does not hold for extremely obese or extremely thin individuals; 

 in infants the proportion is lower — about ^^o- When one-third of 

 the total amount of blood is lost rapidly, a marked fall of blood pres- 

 sure occurs; loss of one-half of the total amount may be fatal, and loss 

 of|more than that at one time usually is fatal. The chief cause of 

 death following large hemorrhages is the low blood pressure rather 

 than the loss of any of the constituents of the blodd; hence the suc- 

 cessful results of the use of physiological salt solution after severe 

 hemorrhage. The number of corpuscles may be greatly reduced after 

 several small hemorrhages, even to as low as 11 per cent, of the normal 

 number (Hayem), without fatal results, because in the intervals be- 

 tween the hemorrhages enough fluid has been taken up by the blood 

 to^maintain the blood pressure within safe limits. After a severe 

 hemorrhage the composition of the blood changes rapidly, for the 

 fluids contained within the tissues and lymph-spaces pass into the blood 

 in large amounts. This helps to maintain blood pressure, but results 

 in the blood containing a large proportion of water and salts and a smal- 

 ler amount of protein and red corpuscles; the "total alkalinity" also 

 falls, largely because of the scarcity of ''fixed alkali, " on account of the 

 poverty in corpuscles and blood proteins. The proportion of water 

 increases at first more rapidly than the proportion of salts, and as a 

 consequence the size of the red corpuscles is increased because of im- 

 bibition of water; indeed, it is possible that this may even be sufficient 

 to cause hemolysis, which will happen if the isotonic strength of the 



*" Metabolism in anemia reviewed bj' Mohr, Handbuch d. Biochem., 1910 (IV 

 (2)), 372. 



^' Concerning local anemia, see "Infarcts." 



