Thursday, September 18, 2008

Classification of Anemia


Anemia is a disorder that results in a decrease in the ability of the blood to carry oxygen. Anemia is itself not a diagnosis but merely a sign of underlying disease. The initial classification of anemia is best accomplished by examination of the data from a hematology analyzer and by an examination of the peripheral blood smear. The physician most commonly classifies anemias initially by the instrument's red cell indices, especially the mean corpuscular volume (MCV). On newer counters, the red cell distribution width (RDW) or red cell morphology index (RCMI) is another useful measurement. The anemia may be microcytic, normocytic, or macrocytic.


Anemia is usually classified according to:

  • Etiology
  • Pathophysiology
  • Morphology


This is classification by cause. An anemia may be due to blood loss which may be due to many causes, eg; excessive vaginal bleeding due to functional menorrhagia, malignancy or endometriosis.


This classification is based on the actual red cell defect like decreased red cell production or increased red cell destruction. In other words the anemia can be classified as:

  • Nonregenerative
  • Regenerative

In many cases either defect are operative or there is uncertainty as to the exact defect which is operative.


This is a classification based on cell size and color. This classification is usually used in the laboratory as we actually see the cells. It is not entirely satisfactory as an anemia due to chronic bleeding may be normocytic at one point, microcytic later and microcytic hypochromic even later.In fact the most often used classification system is a combination of the pathophysiologic


All in all, these classifications will aid in treatment of the disease. It is important to know all these classification so that the diagnosis done will be more accurate and precise. Among the first step of diagnosis is screening. Screening is usually done with the CBC or "complete blood count". The exact procedure in a CBC depends upon the instrumentation in the laboratory. Most laboratories now use automated, multiparameter instruments which will provide results for the following parameters:



red cell count





white cell count

platelet count


automated differential

histograms and scattergrams

As a person who’s going to be working in the lab, assessing the sample, one should also know how to observe a stained blood film to differentiate one anemia from another. A stained blood film should be examined whenever any of the above parameters are abnormal. Examination of the blood film can identify a large range of erythrocyte, leukocyte and thrombocyte changes. The presence of red cell inclusions indicates abnormal erythropoiesis or an increased rate of red cell destruction while poikilocytes indicate a severe red cell abnormality. In some instances poikilocytes can suggest a specific diagnosis. Changes in leukocytes and platelets can provide a clue as to the etiology of an anemia. Some of these changes will be detected by current automated instrumentation. Once a tentative diagnosis is made special tests can be performed to confirm the diagnosis. These include iron studies, vitamin studies, hemoglobin studies, enzyme levels, bone marrow aspirate or biopsy, red cell survival studies etc.

Plus, one should make a thorough diagnosis so that errors can be avoided. Some of the errors are; errors in reporting or recording of results, inadequate study of the blood film, failure to assess indices, failure to do retic count, failure to note rouleux or blue background on film.

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