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Red and White Blood Cell Counts

Published: 2013-08-25 - Updated: 2022-08-06
Author: Thomas C. Weiss - Contact: Disabled World (
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On This Page: Summary - Defining Red and White Blood Cells - Main Article - About/Author

Synopsis: Article provides information regarding red and white blood cell count used to identify diseases and to monitor human health problems. Blood tests are used to both measure and inspect a person's red blood cells, white blood cells, and platelets. A doctor might order a blood smear, also referred to as a 'peripheral blood smear' or 'manual differential,' if a person's Complete Blood Count (CBC) results are unclear or abnormal.


Red and White Blood Cells

A red blood cell is a type of blood cell made in the bone marrow and found in the blood. Red blood cells contain a protein called hemoglobin, which carries oxygen from the lungs to all body parts. Checking the number of red blood cells in the blood is usually part of a complete blood cell (CBC) test. It may be used to look for conditions such as anemia, dehydration, malnutrition, and leukemia and is also called erythrocyte and RBC.

A white blood cell is a type of blood cell made in the bone marrow and found in the blood and lymph tissue. White blood cells are part of the body’s immune system. They help the body fight infection and other diseases. Types of white blood cells are granulocytes (neutrophils, eosinophils, and basophils), monocytes, and lymphocytes (T cells and B cells). Checking the number of white blood cells in the blood is usually part of a complete blood cell (CBC) test. It may look for infections, inflammation, allergies, and leukemia called leukocyte and WBC.

Main Digest

Blood counts may be used to identify diseases and to monitor a person's health. Though the various tests related to blood counts cannot diagnose lymphoma, they can alert a doctor to an issue in a person's body and prompt a doctor to perform appropriate tests. Since most chemotherapy regimens, for example, result in low blood counts in a person, the tests become very important in monitoring a person's health after a diagnosis has been achieved.


The cells that circulate in the bloodstream are generally divided into three types:

A complete blood count (CBC), also known as full blood count (FBC), full blood exam (FBE), or blood panel, is a test panel requested by a doctor or other medical professional that gives information about the cells in a patient's blood. A scientist or lab technician performs the requested testing and provides the requesting medical professional with the results of the CBC. Abnormally high or low counts may indicate the presence of many forms of the disease, and hence blood counts are amongst the most commonly performed blood tests in medicine, as they can provide an overview of a patient's general health status.

Blood tests measure and inspect a person's red blood cells, white blood cells, and platelets. A 'Complete Blood Count (CBC)' tests all three cell types. The test only requires a few drops of a person's blood. Nearly all cell counting is done by machine. However, hematology technicians examine a person's blood cells under a microscope to ensure no abnormalities in size or shape.

Red Blood Cells (RBC):

Red blood cells carry oxygen from a person's lungs to the rest of their body. A depletion of red blood cells may lead to anemia. Anemia results in dizziness, fatigue, or even more serious symptoms if untreated. Typical red blood cell count (RBC) levels are:


The amount of RBCs is also shown through a person's 'Hemacrit,' which is a ratio of the number of RBCs to the blood volume. Common values are:


Hemoglobin is a molecule on an RBC that allows it to carry oxygen. Low hemoglobin counts may also result in fatigue and anemia. Typical levels are:

Illustration of red blood cells inside an artery.
Illustration of red blood cells inside an artery.

White Blood Cell Count (WBC)

White blood cells contain the immune cells that attack and remove viruses and bacteria in a person's body. Low WBC counts may indicate that a person is in danger of infection. High WBC counts might indicate an existing infection, tissue damage, or leukemia. Typical levels are 4,000-10,800 cells per micro-liter of a person's blood. There are several different types of WBC, and their values differ; they are:

Neutrophils are the body's first line of defense against infection and disease. These cells assist with inflammation due to cuts or bacteria in the skin and are responsible for pus. A low level of neutrophils, referred to as 'neutropenia,' leaves a person susceptible to disease. Smoking and obesity increase a person's neutrophil count; for each pack of cigarettes a person smokes each day, their granulocyte count may increase.


T-cells and B-cells are lymphocytes. Depleting these levels may also increase a person's risk of experiencing an infection. Typical levels are:

Platelet Count:

Platelets are responsible for blood clotting. Typical levels are 133,000-333,000 platelets per microliter of a person's blood. If the level decreases to below 30,000, referred to as 'thrombocytopenia,' abnormal bleeding may happen. Counts below 5,000 are considered to be life-threatening.

The Meaning of Blood Counts

What do blood counts mean? In an attempt to understand blood counts, the following items will be presented:

Blood Smear

A doctor might order a blood smear, also referred to as a 'peripheral blood smear' or 'manual differential,' if a person's Complete Blood Count (CBC) results are unclear or abnormal or if the doctor thinks a disease or disorder might be disrupting the person's normal blood cell production. The test helps to determine whether red cells, white cells, and platelets are average in appearance and number. It is also used to determine the proportion of each type of white cell relative to the person's total white cell count. The results also help a doctor monitor cell production and maturity before and during blood cancer therapy.

A blood smear is performed using a single drop of a person's blood. The blood is spread on a glass slide, dried, and then stained with a dye. The sample is examined under a microscope to calculate the number of each type of blood cell. A doctor also compares the sample cell's shape, size, and general appearance to average ones. As for the results of a blood smear - the test may show the presence of immature or abnormal cells, which may indicate an underlying condition or provide information about its severity and suggest the need for additional testing.

Karyotype Test

A 'karyotype' test identifies and evaluates changes to the expected chromosome arrangement, shape, size, and number in a sample of a person's blood or bone marrow cells. The test provides a map of the 46 human chromosomes of a cell. In some instances, a dye called 'Giemsa' might be used as a stain to make the banding pattern of chromosome pairs easier to see. The process is also referred to as 'G-banding,' and the finding may assist a doctor in developing a more specific treatment plan.

Flow Cytometry

Flow cytometry analyzes a person's blood or bone marrow cells to determine whether a high white cell count results from blood cancer. The test involves identifying cells as they flow through an instrument called a, 'flow cytometer.' Flow cytometry measures the number and percentage of cells in a person's blood sample and cell characteristics such as shape, size, and the presence of biomarkers on the cell surface. The method helps to sub-classify cell types so a person's doctor can decide on the best treatment plan. Flow cytometry can also detect residual levels of disease after treatment, helping the person's doctor to identify disease relapse and restart treatment as needed.

Blood Chemistry

A person's blood chemistry is examined using a group of tests called 'chemistry panels.' The tests provide information concerning a person's general health. Depending upon the type of panel, the tests can measure:

A person is asked to fast before the test. After their blood is drawn, it is placed in a tube or tubes and often left to clot. The fluid portion of the person's blood that remains after clotting, called the 'serum,' is used for various chemical studies. The results provide a doctor with information concerning a person's overall health and identify potential issues that might require treatment. Higher levels of certain blood proteins may be signs of disease severity. High levels of uric acid may sometimes indicate disease.


Immunophenotyping identifies a particular type of cell in a sample of a person's blood, lymph node cells, or bone marrow. The procedure may be important in helping to choose the best treatment for the person. For example, immunophenotyping may distinguish myeloid leukemic cells from lymphocytic leukemic cells, average lymphocytes from leukemic lymphocytes, and B-cell lymphocytes from T-cell lymphocytes. Immunophenotyping also shows whether a person's cells are 'monoclonal' or derived from a single malignant cell.

White Cell Differential

A white cell differential, also referred to as a 'CBC plus differential,' or a 'differential,' measures the amount of different white cells in a person's blood. A white cell differential is many times included as part of the CBC. The test helps to determine a person's body's ability to react to and fight infections. It may also identify various types and stages of blood cancers, detect the existence and severity of infections, and measure a person's response to chemotherapy. The absolute neutrophil count (ANC) is the number of neutrophils - a type of white cell in a person's blood that will fight infections.

After a person's blood is drawn, it is placed on a stained blood slide and examined. A pathologist determines the percentage of different types of white cells present. Abnormal patterns of white cells might point to infections, immune disorders, leukemia, inflammation, and other issues.

Polymerase Chain Reaction

Polymerase chain reaction (PCR) is an extra-sensitive test, one that measures the presence of certain biomarkers in a person's blood or bone marrow. It measures any remaining blood cancer cells not found by cytogenetic methods such as FISH (explained below). PCR is used to diagnose and check a person's molecular response to treatment. PCR can detect a specific DNA abnormality or marker found in people with certain blood cancers such as chronic myeloid leukemia and acute promyelocytic leukemia. PCR allows the more sensitive follow-up of people in remission and can help determine whether a person needs additional treatment.

Fluorescence in Situ Hybridization (FISH)

Fluorescence in situ hybridization (FISH) is a lab test performed on a person's blood or bone marrow cells to detect chromosome changes in blood cancer cells. FISH helps identify genetic abnormalities that might not be evident by examining cells under a microscope, which helps to ensure that a person receives appropriate treatment. After treatment, doctors use FISH around every 3-6 months to determine whether the therapy works.

Fluorescence in situ hybridization (FISH) is a lab test performed on your blood or bone marrow cells to detect chromosome changes (cytogenetic analysis) in blood cancer cells. FISH helps identify genetic abnormalities that may not be evident by examining cells under a microscope. This helps ensure that the proper treatment is used. Once treatment begins, doctors use FISH - usually every three to six months - to determine whether therapy is working.

In Summary:

Note: Causes shown below are just some of the possible causes for a high/low count. Work with your doctor for an accurate diagnosis.

What does a high red blood cell count mean?

A high red blood cell count (polycythemia) indicates an excess of red blood cells circulating in your bloodstream. Red blood cells (erythrocytes, or RBCs) are produced in your bone marrow and transport oxygen from your lungs to tissues throughout your body. A high red blood cell count is also called erythrocytosis (uh-rith-roh-sie-TOH-sis). A high red blood cell count means your body produces too many red cells and is a symptom, not a disease.

What does a low red blood cell count mean?

If the RBC count is low (anemia), the body may not be getting the oxygen it needs. A low RBC count may indicate bleeding, kidney disease, bone marrow failure (for instance, from radiation or a tumor), malnutrition, or other causes. A low count may also indicate nutritional deficiencies in iron, folate, vitamin B12, and vitamin B6.

What does a high white blood cell count mean?

When a high white cell count is present, infection is usually the first cause, and your doctor may follow up by ordering a differential count. This reveals the quantity of each type of white blood cell present which can give a clue as to the kind of infection present. For example, eosinophil counts go up with parasitic infections and allergic disorders. Medications can also be a cause of a high white blood count.

What does a low white blood cell count mean?

Low white cell counts are associated with chemotherapy, radiation therapy, leukemia (as malignant cells overwhelm the bone marrow), myelofibrosis, and aplastic anemia (failure of white and red cell creation, along with poor platelet production). In addition, many common medications can cause leukopenia (e.g., minocycline, a commonly prescribed antibiotic). There are also reports of Leukopenia caused by Depakote (Divalproex Sodium or Valproic Acid), a drug used for epilepsy (seizures), mania (with bipolar disorder), and migraine.

Human Blood Facts and Statistics

View further human blood facts and statistics, as well as other amazing human body facts.

Author Credentials:

Thomas C. Weiss is a researcher and editor for Disabled World. Thomas attended college and university courses earning a Masters, Bachelors and two Associate degrees, as well as pursing Disability Studies. As a Nursing Assistant Thomas has assisted people from a variety of racial, religious, gender, class, and age groups by providing care for people with all forms of disabilities from Multiple Sclerosis to Parkinson's; para and quadriplegia to Spina Bifida.

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Cite This Page (APA): Thomas C. Weiss. (2013, August 25). Red and White Blood Cell Counts. Disabled World. Retrieved September 24, 2023 from

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