ANEMIAS 535 



the renal tubules had been previously damaged to a moderate degree.* The 

 subject has been reviewed by Foy and co-workers (938). 



The position is very similar with regard to the renal damage in "crush 

 syndrome" which had been noticed during the war of 1914-1918 {1958), 

 but was more fully studied on the victims of the air-blitz in England during 

 the last war {386). If large muscles are crushed for a prolonged period, but 

 to a minor degree also without prolonged crush {1018), myohemoglobin is 

 found in the urine, and the kidneys show the same signs of damage as after 

 incompatible transfusion. Bywaters has been able to produce renal damage 

 by injections of myohemoglobin into rabbits {388), while Bing {263) did 

 not find it after injections into acidotic dogs. Some observations {cf. 1018, 

 1096a,3673)f indicate the importance of breakdown of ATP as causal factor 

 of the renal damage. The clearance of myohemoglobin from plastna is 25 

 times as fast as that of hemoglobin and about 60% of the creatinine clear- 

 ance. The renal threshold is far lower (15-20 mg. per 100 ml. plasma) 

 {401,1867,3154^) than that of hemoglobin. 



Spontaneous myohemoglobinuria occurs in a paralytic myohemoglo- 

 binuria of the horse and in humans in the so-called Haff disease {387,2854). 



6. ANEMIAS 

 6.1. Introduction 



A full discussion of anemias is beyond the scope of this book. 

 From a physiological point of view we can divide anemias into four 

 classes, (a) Anemias with decreased production of red cells, of hemo- 

 globin, or of both. These will be of interest to us mainly in connection 

 with the anabolism of hemoglobin (Chapter XIII). (6) Production 

 of faulty erythrocytes, which are broken down more readily. Idio- 

 pathic hemolytic anemia as well as pernicious anemia belong to this 

 class, (c) Anemias due to increased destruction of normal erythro- 

 cytes, {d) Anemias due to loss of blood by external or internal 

 hemorrhage. 



It is possible to distinguish between classes (a) and (6) by measur- 

 ing the life span of the erythrocyte or the rate of hemoglobin dis- 

 integration, but in many instances complete evidence is not yet 

 available. Where the causal agent is unknown, it may be difficult to 

 distinguish between (6) and (c). 



Probably too much attention has been paid so far to the "fra- 

 gility" of the red cell, i.e., its osmotic resistance. In vivo the erythro- 

 cyte is not subject to the action of hypotonic solutions, and while a 

 high sensitivity to hypotonicity may indicate a decreased resistance 



* Cf. also Lalich {1634a). 



fC/. also Meyer and co-workers {1930a). 



