Guide to CBC (Complete Blood Count and Differential

Chemotherapy works by killing rapidly dividing cells.  The target of chemotherapy is cancer cells.  However, our bodies have rapidly dividing cells that are normal tissue as well.  This includes:  bone marrow, gastrointestinal tract and mucous membranes,  and hair, skin, nails.  Chemotherapy can also affect the function of our reproductive organs.  Your medical healthcare provider can monitor the effects and toxicity of your chemotherapy treatment by monitoring your CBC results.

Please note that some lab results will vary slightly between males and females, and between some labs across the country. 

The WBC's, RBC's, Hgb, Hct, PLT and MPV are the cells that your medical provider will monitor that give the most important information about how your body is effected by the chemotherapy, and shows how well the body is able to perform its normal functions, such as resist infection, carry oxygen, protect against bleeding and maintain energy levels.

WBC:  white blood cells or leukocytes.  White blood cells help the body to fight infections.  There are several different types of white cells that have different jobs.  The WBC is the total of all the white cells counted.
RBC:  red blood cells.  These are also called erythrocytes or corpuscles.  Immature red blood cells are called reticulocytes.  RBC's carry oxygen from the lungs to the tissues of the body.
Hgb:  hemoglobin.  Hemoglobin is the pigment of the red blood cells that actually carries the oxygen.
HCT:  hematocrit.  This is the percentage of RBC's in a volume of whole blood in your body.  Other names for this part of the RBC is PCV:  packed cell volume
PLT:  platelets or thrombocytes.  These cells help the blood to form a clot when your body has had a trauma or is bleeding.

MCH, MCHC, MCV, RBC, Hct, Hgb all give us information in the diagnosis of anemias.  Anemia is a condition that is defined as:  a lack of the proper amount of red blood cells.
MPV:  mean platelet volume.  This is the average volume of platelets.  A high MPV means that there is the presence of larger platelets.  A low MPV indicates that the platelets are smaller than normal.
MCV:  mean corpuscular volume.  This is the calculation of the average volume of a RBC. 
The calculation is:  hematocrit RBC count.
MCH:  mean corpuscular hemoglobin.  This is the calculation of the average weight of Hgb of each RBC.  This calculation is:  hemoglobin RBC.
MCHC:  mean corpuscular hemoglobin concentration.  This number tells us the concentration of hemoglobin in an average RBC.  The calculation is  hemoglobin hematocrit.
RDW:  red cell distribution width.  This is a numerical expression of the degree of variation in the volume of the population of read blood cells.  Normally, as the new, normal size cells are produced, the RDW increases.  It will also decrease, as the normal cell population gains the majority.

DIFFERENTIAL:  A differential count calculates the total white blood cells and categorizes their different types  The differential is reported as a percentage and an absolute number by type of cell.

OTHER TERMINOLOGY:
Granulocyte:  white blood cells with a grainy appearance under a microscope.  Neutrophils, eosinophils and basophils are all granulocytes.  Neutrophils are further classified as either 'bands' or 'segs'.  This defines the level of maturity of these cells.  The purpose of this type of cell is to fight infection.
Polymorphonuclear leukocytes/PMN's'Polys:  these refer to granulocytes which are neutrophils, eosinophils and basophils.  The name means, "possessing a nucleus (or center) consisting of many parts or lobes.  This is another descriptive name for white blood cells.
Blast, myelocyte, metamyelocyte, progranulocyte:   These are immature WBC's that are not normally in the peripheral blood circulation.

3/2/04 AHF/Rose Medical Center