Red Blood Cells
Red blood cells carry oxygen from the lungs to the tissues of the body. They also carry carbon dioxide, the waste product of the tissues, back to the lungs where it is expelled. Red blood cells are also called erythrocytes. Red blood cell counts can be affected when leukemic cells crowd out the red blood cells or the bone marrow is damaged and cannot properly produce enough red blood cells. Red blood cell counts can also be altered by chemotherapy drugs or a vitamin deficiency. If the number of red blood cells falls very low, the result is anemia, a condition marked by fatigue, paleness, and sometimes shortness of breath. Red blood cell counts are included in a complete blood count, or CBC. Hematocrit indicates what percentage of the total blood volume consists of red blood cells. It is also called a packed cell volume, or PCV.
Normal counts are:
- 42-50% in adult males
- 36-45% in adult females
- 34-40% in children
Hemoglobin is the protein in red blood cells that carries oxygen.
Normal levels:
- 13-17 grams per 100 milliliters in adult males
- 11.5-16 grams per 100 milliliters in adult females
- 11.5-13.5 grams per 100 milliliters in children
Platelets
Platelets are tiny particles that help to stop bleeding by plugging up an injury to a blood vessel. The number of platelets can drop due to chemotherapy or the disease itself. An abnormally low platelet count, a condition known as thrombocytopenia, can put a person at risk of excessive bleeding. Thrombocytosis is a condition in which the platelet count is too high. Platelet counts are included in a complete blood count or CBC.
Normal platelet counts:
- 160 to 400 thousand platelets /mm3 in adults
- 150 to 500 thousand platelets /mm3 in children
White Blood Cells
White blood cells are produced by the body to fight off infection by bacteria and other foreign substances. There are several different types of white blood cells: neutrophils (polys, granulocytes), eosinophils, basophils, monocytes, and lymphocytes. The type of leukemia a person has usually depends on which type of white blood cells are not being properly produced in the body. An abnormal white blood cell count is often one of the first signs of leukemia. Those with acute leukemia may have abnormally high or low white blood cell counts, while those with chronic forms of the disease always have abnormally high counts. The counts can also be affected by treatments.
Normal white blood cell count:
The white blood cell differential indicates what portion of the total white blood cell count is made up of each type of cell. A normal differential might read as follows:
- neutrophils (polys, granulocytes) 50-60%
- lymphocytes 25-35%
- monocytes 3-10%
- eosinophils 1-3%
- basophils 0-1%
The neutrophil section is sometimes divided further into segmented neutrophils and band neutrophils. An absolute neutrophil count, or ANC, indicates how many of the total white blood cells are neutrophils. As an example, say the neutrophils measure 50 percent in the white blood count differential, and the total white blood count is 10,000. Multiply .50 times 10,000 to reach an ANC of 5,000. An ANC of 1,000 or higher usually means the person is not at serious risk of infection from normal activities. With a lower count, the risk of infection may be high.
Several other terms are commonly used to describe white blood cell counts.
- Leukopenia means that white blood cell counts are lower than normal.
- Neutropenia indicates that the level of granulocytes (neutrophils, polys) is lower than normal. It usually describes a neutrophil count that is lower than 1,000 cells/mm3.
Blasts
A blast is a general name for the immature form of white blood cells. Blasts represent the stage of blood formation between the original stem cells produced in the bone marrow and more mature forms of blood cells. Normal blasts mature through this life cycle, while abnormal, leukemic blasts remain immature and can build up in the body. In healthy people, blasts are usually found in limited numbers in bone marrow and not at all in circulating blood. Blast counts are routinely measured in the bone marrow and blood samples of leukemia patients. A normal blast count in the bone marrow is less than 5 percent. When leukemia is present, the blast count is usually between 20 and 100 percent. Many people who have acute leukemia have blasts in the circulating blood when first diagnosed.
Cell Appearance
When looking at blood and bone marrow cell samples under a microscope, a doctor can recognize many features that are characteristic of one or more types of leukemia. Some of these features are:
- The maturity of cells. Cells may appear to be mature cells that are going through a normal life cycle or immature cells that are no longer working properly.
- The size and shape of cells, as well as the presence of certain cellular structures. Some features help to determine which type of leukemia is involved; for example, Auer rods are structures that indicate acute myeloid leukemia.
- Whether the leukemic cells are derived from lymphoid or myeloid cells. Myeloid cells, for example, can often be identified by the presence of Auer rods or the use of stains. Lymphocytic leukemia cells, however, usually require immunophenotyping to determine the type of disease present. They don't have any recognizable physical features that can be seen under a microscope.
Other Blood Chemistry Tests
Other blood tests, called blood chemistry tests, may be used to help track how well a patient's liver and kidneys are functioning. Those organs can show side effects of chemotherapy and can also be affected by the leukemia itself.
