The Complete Blood Count (CBC) and CBC With Differential Morphology:
Brief Summary:
The complete blood cell count is a very common blood panel ordered by physicians and healthcare personnel and can give a lot of information about a person's cells and health. The blood includes three components: red blood cells, white blood cells and platelets. The role of the red blood cells is to carry oxygen and hemoglobin to the body's tissues and organs. When there are not enough red blood cells or if they become destroyed, then the person may become anemic and not have enough oxygen or hemoglobin. This panel can help them determine this and start appropriate treatment. If there are not enough or too much of particular white blood cells, this also helps with diagnosis of infection types, inflammation, immunity, etc...If platelets are too low, then the blood cannot clot properly and this can lead to hemorrhages or excessive bleeding. If the platelets are too high, the blood may form clots, which can cause things like a stroke or blockage or pulmonary embolism (a blood clot in the lungs).
Blood is collected by a phlebotomist through venipuncture (blood collected from the veins) in a lavender top EDTA tube and sent to the laboratory, where it is tested by a medical laboratory scientist or technician and the results are reported to healthcare personnel. The EDTA in the blood collection tube prevents the blood from clotting. An automated analyzer counts the cells, and some differentiate between the types of cells and if there are any abnormalities. Lab personnel may need to make a smear of blood on the slide and stain it with a special stain to look at it manually to see if there are any abnormalities or to verify counts and morphology of the cells.
COMPONENTS OF THE CBC:
- Total number of red blood cells (RBC) per litre (low may indicate iron deficiency anemia; high may indicate polycythemia)
- Hemoglobin (Hgb) expressed in grams (g) per deciliter (low is a sign of a type of anemia)
- Hematocrit, or packed red blood cell volume (Hct) (PCV): the number of red blood cells in whole blood cell volume; also called the red blood cell indices
- Mean corpuscular volume (MCV) (the average width of the red blood cells expressed in femtoliters)
- Smaller means a microcytic anemia
- Larger means a macrocytic anemia
- Normal means a normocytic anemia or no anemia at all
- Mean corpuscular hemoglobin concentration (MCHC) (average amount of hemoglobin per rbc expressed in pictograms)
- Less could indicate an iron-deficiency anemia
- More could indicate an iron-overloading anemia
- Red cell distribution width (RDW) (variation of size of RBCs)
- Platelets (count) (PLT) (too high may be a clot; too low may mean drug toxicity, immune condition, cancer, on chemotherapy, liver disease)
- Mean platelet volume (MPV) (average platelet size) (Platelets may be smaller than usual, large, or giant)
- Total white blood cells (WBC) expressed as absolute number per unit volume (high indicates some type of infection or inflammation, disease, or condition)
- Neutrophils (polymorphonuclear or "segs" or bands); high may indicate bacterial or acute viral infection)
- Lymphocytes (higher in viral infections and some types of cancers)
- Monocytes (higher in bacterial infections and some types of cancers)
- Eosinophils (higher in parasite infections, allergies, asthma, allergic reactions, infections, some types of cancers)
- Basophils (higher in certain types of cancers like leukemia or lymphoma, allergies, asthma, allergic reactions)
TERMINOLOGY:
- Leukocytosis: high WBC count
- Leukopenia: low WBC count
- Neutrophilia: high neutrophil count
- Neutropenia: low neutrophil count
- Lymphocytosis: high lymphocyte count
- Lymphopenia: low lymphocyte count
- Monocytosis: high monocyte count
- Basophilia: high basophil count
- Basopenia: low basophil count
- Eosinophilia: high eosinophil count
- Eosinopenia: low eosinophil count
- Thrombocytosis: high platelet count
- Thrombocytopenia: low platelet count
- Anisocytosis: RBC variation in size
- Poikilocytosis: RBC variation in shape
- Macrocytosis: larger than normal size red blood cells
- Microcytosis: smaller than normal size red blood cells
- Rouleaux: red blood cells stick together like "stacked coins"
- Agglutination: red blood cells clump together
- Hypochromia: red blood cells are paler in the center than normal
- Polychromasia: red blood cells are larger and have a purple-blue-gray tint to them
- Variant or atypical: difference in size of cell, mostly referring to lymphocytes (resting is round; atypical or reactive the cytoplasm hugs the red blood cells or pushes them away; variant cytoplasm is bubbling out or ruffled; cell may be a blast or blast-like)
- Toxic granulation: darker granules due to infection, sepsis, hypoxia, inflammation
- Hypogranulation: missing granules
- Degranulation: releasing granules
- Smudge cells: look damaged, smeared, like baskets; very fragile
- Vacuolization: cytoplasm contains holes or bubbles
- Clumping: look for platelets stuck together
- Erythrocytosis or polycythemia: increase in RBC count
- Anemia or erythroblastopenia: decrease in RBC count
- Pancytopenia: all cell lines affected
- Left Shift: an increase in IG's (immature granulocytes/leukocytes), such as band PMN's (polymorphonuclear neutrophils) in the circulating blood caused by the release of cytokines in the bone marrow (IL-1 and TNF), stimulating the release of cells from a reserve pool in the bone marrow, resulting in the increase in immature blood cells in the peripheral bloodstream
- Inflammation
- Infection
- Sepsis (neutrophils may also contain toxic granulation, Dohle bodies, and/or vacuoles)
- Anemia
- Hypoxia
- Shock
- Hematopoiesis: the process of blood production and maturation (occurs mainly in the bone marrow)