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Idiopathic Secondary Drugs Infection

Microangiopathic

Fig. 1-2. Approach to the diagnosis of anemia by MCV and reticulocyte count.

The reticulocyte count must be adjusted for the level of anemia to obtain the reticulocyte index,* a more accurate reflection of erythropoiesis. In patients with bleeding or hemolysis, the reticulocyte index should be at least 3%, whereas in patients with anemia due to decreased production of red cells, the reticulocyte index is less than 3% and frequently less than 1.5%.

Mean corpuscular volume and red cell distribution width (RDW) indices, available from automated electronic blood-counting equipment, are extremely helpful in defining the morphology and the nature of the anemia and have led to a classification based on these indices (Table 1-3).

In more refractory cases of anemia, bone marrow examination may be indicated. A bone marrow smear should be stained for iron, where indicated, to estimate iron stores and to diagnose the presence of a sideroblastic anemia. Bone marrow examination may indicate a normoblastic, megaloblastic, or sideroblastic morphology. Figure 1-3 presents the causes of each of these findings.

Table 1-4 lists various laboratory studies helpful in the investigation of a patient with anemia. The investigation of anemia entails the following steps:

1. Detailed history and physical examination (see Table 1-1)

2. Complete blood count, to establish whether the anemia is only due to one cell line (e.g., the red cell line only) or is part of a three-cell-line abnormality (abnormality of red cell count, white blood cell count, and platelet count)

3. Determination of the morphologic characteristics of the anemia based on blood smear (Table 1-2) and consideration of the MCV (Figures 1-1 and 1-2) and RDW (Table 1-3) and morphologic consideration of white blood cell and platelet morphology

Table l-3. Classification of Nature of the Anemia Based on MCV and RDW
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