CBC

How the Test is Performed:
Adult or child:
Blood is drawn from a vein ( venipuncture ), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding .

Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to Prepare:
Adult:
There is no special preparation needed.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:



How it Feels:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing .

Risks:

  • excessive bleeding
  • fainting or feeling lightheaded
  • hematoma (blood accumulating under the skin)
  • infection (a slight risk any time the skin is broken)
  • multiple punctures to locate veins



Why this Test is Performed:
The CBC is a screening test, used to diagnose and manage numerous diseases. It can reflect problems with fluid volume (such as dehydration ) or loss of blood. It can show abnormalities in the production, life span, and destruction of blood cells. It can reflect acute or chronic infection, allergies , and problems with clotting.

MCV, MCH, and MCHC values reflect the size and hemoglobin concentration of individual cells and are useful in the diagnosis of types of anemia .

Normal Values:

  • RBC (varies with altitude):
    • male: 4.7 to 6.1 million cells/mcl
    • female: 4.2 to 5.4 million cells/mcl

  • WBC : 4,500 to 10,000 cells/mcl
  • hematocrit (varies with altitude):
    • male: 40.7 to 50.3 %
    • female: 36.1 to 44.3 %

  • hemoglobin (varies with altitude):
    • male: 13.8 to 17.2 gm/dl
    • female: 12.1 to 15.1 gm/dl

  • MCV: 80 to 95 femtoliter
  • MCH: 27 to 31 pg/cell
  • MCHC: 32 to 36 gm/dl

Note: cells/mcl = cells per microliter; gm/dl = grams per deciliter; pg/cell = picograms per cell

Abnormal Results:
High numbers of RBCs may indicate:

Low numbers of RBCs may indicate:

Low numbers of WBCs (leukopenia) may indicate:

  • bone marrow failure (for example, due to granuloma (granular tumor), tumor, or fibrosis)
  • presence of cytotoxic substance
  • collagen-vascular diseases (such as lupus erythematosus )
  • disease of the liver or spleen
  • radiation exposure

High numbers of WBCs (leukocytosis) may indicate:

Low hematocrit may indicate:

  • anemia (various types)
  • blood loss (hemorrhage)
  • bone marrow failure (for example, due to radiation, toxin, fibrosis, tumor)
  • hemolysis (RBC destruction) related to transfusion reaction
  • leukemia
  • malnutrition or specific nutritional deficiency
  • multiple myeloma
  • over hydration
  • rheumatoid arthritis

High hematocrit may indicate:

Low hemoglobin values may indicate:

  • anemia (various types)
  • blood loss

Additional conditions under which the test may be performed:



Cost:
The cost for the tests are:



Special Considerations:
Red blood cells transport hemoglobin which, in turn, transport oxygen. The amount of oxygen received by tissue depends on the amount and function of RBCs and hemoglobin. The MCV, MCH, and MCHC reflect the size and hemoglobin content of individual red blood cells.

The hematocrit is an expression of the proportion of whole blood that is composed of red blood cells (since the contribution by the WBCs is almost negligible). The hematocrit is a compound measure of RBC number and size.

White blood cells are mediators of inflammation and the immune response . There are various types of WBCs that normally appear in the blood: neutrophils (polymorphonuclear leukocytes; PMNs), band cells (slightly immature neutrophils), T-type lymphocytes (T cells), B-type lymphocytes (B cells), monocytes, eosinophils , and basophils.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.


Sickle cell anemia is an inherited blood disease in which the red blood cells produce abnormal pigment (hemoglobin). The abnormal hemoglobin causes deformity of the red blood cells into crescent or sickle-shapes, as seen in this photomicrograph.



This picture shows large, dense, oversized, red blood cells (RBCs) that are seen in megaloblastic anemia. Megaloblastic anemia can occur when there is a deficiency of vitamin B-12.



This photomicrograph shows one of the abnormal shapes that red blood cells(RBCs) may assume, a tear-drop shape. Normally, RBCs are round.



This photomicrograph shows normal red blood cells (RBCs) as seen in the microscope after staining.



Eliptocytosis is a hereditary disorder of the red blood cells (RBCs). In this condition, the RBCs assume an elliptical shape, rather than the typical round shape.



Spherocytosis is a hereditary disorder of the red blood cells (RBCs), which may be associated with a mild anemia. Typically, the affected RBCs are small, spherically shaped, and lack the light centers seen in normal, round RBCs.



Sickle cell anemia is an inherited disorder in which abnormal hemoglobin (the red pigment inside red blood cells) is produced. The abnormal hemoglobin causes red blood cells to assume a sickle shape, like the ones seen in this photomicrograph.



Basophils are a specific type of white blood cell. These cells are readily stained with basic dyes (this is where the name comes from). Note the dark grains inside the cellular fluid (cytoplasm) of this basophil. Basophils make up only a small portion of the number of white blood cells but are important parts of the body's immune response. They release histamine and other chemicals that act on the blood vessels when the immune response is triggered.



Malarial parasites are visible within the red blood cells. They are stained a dark bluish color.



Malaria is a disease caused by parasites. This picture shows dark orange-stained malaria parasites inside red blood cells (a) and outside the cells (b). Note the large cells that look like targets; it is unknown how these target cells are related to this disease.



These crescent or sickle-shaped red blood cells (RBCs) are present with Sickle cell anemia, and stand out clearly against the normal round RBCs. These abnormally shaped cells may become entangled and block blood flow in the small blood vessels (capillaries).



This photomicrograph of red blood cells (RBCs) shows both sickle-shaped and pappenheimer RBCs.



These abnormal red blood cells (RBCs) resemble targets. These cells are seen in association with some forms of anemia, and following the removal of the spleen (splenectomy).