Although anemia may be defined as a decrease in Hb concentration, it may result from a pathologic decrease in the RBC count. Since mature RBCs are fully saturated with Hb, such a decrease means that total blood Hb value will also be affected.
Before commencing transfusion therapy or an extensive workup for the etiology of anemia, [...]
The nine procedures previously described are the basic tests of hematology. Careful selection and interpretation of these procedures can go far toward solving the vast majority of hematologic problems. Other tests may be ordered to confirm or exclude a diagnosis suggested by the results of preliminary studies. These other tests will be discussed in association [...]
Bone marrow aspiration is of help in several situations: (1) to confirm the diagnosis of megaloblastic anemia; (2) to establish the diagnosis of leukemia or multiple myeloma; (3) to determine whether deficiency of one or more of the peripheral blood cellular elements is due to a deficiency in the bone marrow precursors (bone marrow hypoplasia); [...]
The manual procedure that employs a hemocytometer counting chamber and a standard microscope has approximately a 10%-20% error. A some-what similar method that makes use of a phase contrast microscope has a reported error of about 8%. Platelet counting machines can reduce the error even further. Reference values are 150,000-400,000/mm3 (150-400 Ч 109/L) for direct [...]
White blood cell counts may be done either manually using a hemocytometer or with automated cell counters. The error produced by hemocytometer counts is about 4%-8% but may be higher with inexperienced personnel. Automated counters have approximately 2%-4% error. The machine has the disadvantage that WBC counts more than 100,000/mm3 become increasingly inaccurate unless a [...]
Reticulocytes occupy an intermediate position between nucleated RBCs in the bone marrow and mature (nonnucleated, fully hemoglobinated) RBCs. After the normoblast (metarubricyte) nucleus is extruded from the cell, some cytoplasmic microsomes and ribosomes remain for 1-2 days that are not ordinarily visible on peripheral blood smears using Wright’s or Giemsa stain but that can be [...]
This procedure gives a vast amount of information. It allows visual estimation of the amount of hemoglobin in the RBCs and the overall size of the RBCs. In addition, alterations in size, shape, and structure of individual RBCs or WBCs are visible, which may have diagnostic significance in certain diseases. Pathologic early forms of the [...]
Many laboratories perform Hb, RBC, and WBC determinations on electronic particle counting instruments. In certain cases, artifacts may falsely alter results.
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When WBC counts are substantially greater than 50,000/cu mm, the Hb, Hct, RBC, MCV, and MCH values may be falsely increased unless corrective measures are taken (the word “increase” as used here means increase from [...]
Mean Corpuscular Volume (MCV)
Measurement of the MCV uses the effect of the average RBC size on the Hct. If the average RBC size is increased, the same number of RBCs will have a slightly larger cell mass and thus a slightly increased Hct reading; the opposite happens if the average RBC size is smaller than [...]
After centrifugation, the height of the RBC column is measured and compared with the height of the column of original whole blood. The percentage of RBC mass to original blood volume is the Hct. Anticoagulated whole blood is centrifuged in a special tube. Since whole blood is made up essentially of RBC and plasma, the [...]
