624 XIII. HEMOGLOBIN AND PORPHYRIN SYNTHESIS 



{1221) from the observation that iron ascorbate produced a greater hemo- 

 globin formation than corresponded to its iron content. As has been pointed 

 out, this may be explained more readily by assuming a mobilization of iron 

 stores by ascorbic acid through reduction of ferritin iron. 



There is an apparent lack of iron utilization for hemoglobin synthesis in 

 the anemia of chronic infections, in which there is no evidence for increased 

 hemolysis, lack of iron in the body, or aplasia of the bone marrow (2297,2^13). 

 Cartwright, Wintrobe, and co-workers {^12) and Schafer (2432) have shown 

 that the anemia is nevertheless, in a sense, an anemia of iron deficiency. The 

 iron is accumulated in the inflamed (not necessarily infected) tissues* and not 

 available for hemoglobin formation. Serum iron is very low and serum 

 copper abnormally high. According to Hahn, Bale, and Whipple {1088) 

 there may also be a decreased iron absorption. 



5. RELATIONS BETWEEN HEMOGLOBIN FORMATION, 



HEMOGLOBIN CONCENTRATION IN THE BLOOD, 



AND HEMOGLOBIN DESTRUCTION 



5.1. Introduction 



The number of erythrocytes and the hemoglobin concentration in 

 blood are to be considered as governed by the equilibrium between 

 the processes of hemopoiesis and blood destruction. In anemias, of 

 course, a sufficiently great alteration in the rate of hemopoiesis or 

 breakdown may lead to a new equilibrium. In hemolytic anemia, for 

 instance, increased blood destruction, being the cause of the disease, 

 is found together with low hemoglobin concentration in the blood 

 and increased hemopoiesis. 



The equilibrium appears to be self-regulatory, a low hemoglobin 

 content of the blood causing an increase of hemopoiesis, and con- 

 versely a high hemoglobin concentration a decrease of hemopoiesis 

 (c/. 1962). Provided that the lifetime of the erythrocytes remains 

 unaltered, the hemoglobin breakdown in the normal individual will 

 be proportional to the number of cells in the circulation. If, after 

 hemorrhage, newly formed blood with young erythrocytes replaces 

 blood with erythrocytes of average age, the daily breakdown of cells 

 will be diminished until the new cells have reached the end of their 

 life span. These factors are, however, not the only ones involved in 

 the regulation. 



* Recent evidence indicates, however, that the incorporation of iron in the hemo- 

 globin molecule is inhibited and that iron is stored in the liver (Greenberg and 

 co-workers, 1050a) and in the bone marrow (Rath and Finch, 2212a). 



