Red cell turnover of 19 normal subjects and 25 anemic patients was measured with the following technique: erythroid-myeloid ratio of the marrow, reticulocyte counts, plasma iron turnover, red cell utilization of radioiron, and urobilinogen determinations. Measurements of blood production and destruction were so expressed as to allow comparison between normal and anemic individuals of different size and different red cell mass. The usefulness and disadvantages of each procedure in the study of anemia are discussed.

From studies of various types of anemia, it has become apparent that erythropoiesis must be defined in terms of total quantity of red cells produced and in terms of the portion of red cells produced in the marrow which are delivered to the circulating blood (effective versus ineffective erythropoiesis). A quantitative defect alone exists when a normal ratio is maintained between effective and total erythropoiesis. Here, there are changes of similar magnitude of all erythrokinetic indices, although reticulocyte and urobilinogen values are occasionally disproportionately high. The normal marrow appears to be able to increase its effective red cell production to three times normal in acute anemia and six times normal in chronic anemia. In many disease states this maximal quantitative response is impaired.

Dyspoiesis of the marrow is characterized by a dissociation of erythrokinetic indices. Values which reflect total erythropoiesis (i.e., plasma iron turnover, fecal urobilinogen and erythroid-myeloid ratio of the marrow) are considerably greater than the reticulocyte level and red cell utilization of radioiron which represent effective erythropoiesis. Such defects may result in the pattern of a hemolytic process or aregenerative anemia, depending on their severity.

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