Evaluation of the patient with anemia . In the study of the anemic patient, there are three basic parameters that help in the differential diagnosis.
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- 1 Average corpuscular volume of red blood cells (MCV)
- 2 reticulocytes
- 3 Study of the extension of peripheral blood
- 4 Source
Average corpuscular volume of red blood cells (MCV)
Depending on the size of the red cell, the anemias are divided into microcytic (<80 cubic microns), normocytic or macrocytic (> 100 cubic microns). Microcytic anemias. In general, microcytic anemias are usually accompanied by hypochromia , since the size of the red blood cell is reduced in those cases in which the amount of hemoglobin (chromia) decreases. Since hemoglobin is made up of a mixture of iron, globin chains and heme pigment, diseases in which alteration of any of these components occurs generally have a small size.
The most frequent cause of microcytosis is iron deficiency, but anemia of chronic disease, although it is usually normocytic, can be microcytic, as can thalassemias, hereditary sideroblastic anemias, and lead poisoning.
- Normocytic anemias. The most frequent cause is the so-called anemia of chronic disease or due to misuse of iron
(This anemia may occasionally be small cell).
- Macrocytic anemias. Most macrocytic anemias are megaloblastic. The concept of macrocytosis, large size of the red blood cell, should not be confused with that of megaloblastosis, large size of hematological precursors in the bone marrow.
Of course, all megaloblastic anemias are macrocytic, but not all macrocytic anemias are megaloblastic. Anemias secondary to chemotherapy, bone marrow aplasia, hypothyroidism, chronic liver disease, myelodysplastic syndromes, and acquired sideroblastic anemias may have a large red blood cell size.
Also hemolysis or acute bleeding due to the reticulocyte response can simulate a false increase in MCV, since reticulocytes are cells larger than the red blood cell and the machine that counts them does not discriminate it.
Reticulocytes are young red blood cells. Its presence in the peripheral blood translates the function of the bone marrow. The percentage of reticulocytes in reference to the total of red blood cells in peripheral blood is from 1% to 2%. A more accurate measurement of the production of red cells by the bone marrow is obtained by means of the corrected reticulocyte index (CI =% reticulocytes x (Patient Hct. / Normal Hematocrit) / 2, whose value is equal to 1. Anemias that present elevation in the number of reticulocytes they are called regenerative anemias, and the prototype of such anemias is hemolysisor sharp bleeding. Anemias that do not raise or decrease the number of reticulocytes in the blood are called hyporegenerative anemias, and the prototype is medullary aplasia. In general, a not high number of reticulocytes usually translates a disease of the bone marrow itself or a deficiency disorder, which prevents the bone marrow from being able to form blood cells. In this sense, an exception would be the invasion of the bone marrow by metastasis (myelophthysic anemia), in which case the reticulocytes may be increased despite presenting a disease of the bone marrow.
Study of the extension of peripheral blood
This is the study of the morphology of blood cells, not only of the red series, but of the rest of the other series. Example of findings in the extension of peripheral blood and its correlation with some diseases:
- Rouleaux – dysproteinemias, such as multiple myeloma.
- Red blood cells in spurs – kidney failure .
- Dacryocytes or red blood cells in tears – myeloptysis .
- Poikilocytes (these are variations in the shape of the red blood cell ) – myelodysplasia .
- Dianocytes – obstructive jaundice and hemoglobinopathies.
- Prominent basophilic stippling – lead poisoning or anemias
- Polychromatophiles – hemolysis.
- Spherocytes – hereditary spherocytosis or immunohemolysis.
- Heinz bodies (produced by hemoglobin denaturation) – hemolysis by oxidants in glucose deficiency
6 phosphate dehydrogenase or hemoglobinopathies and splenectomized.
- Schistocytes or fragmented red cells – traumatic hemolysis.
- Bodies Howell-Jolly – hyposplenism