Complete Blood Count

COMPLETE BLOOD COUNT

“Morgan, what do you mean, they stick you with a needle and suck out some of your blood? I don’t think I want to do that!”



“It really doesn’t hurt Plucky. And blood tests are an easy, non-invasive way of letting your doctor know what is going on inside of you.”

The first basic blood test, whether you’re having a routine physical or if a problem is suspected, is a Complete Blood Count (CBC). This is not a diagnostic test, it is the starting point for a diagnosis. If this test comes back normal, great, go on your merry way and have a great day. If it shows you have any abnormal values, it tells your doctors where these abnormal values are and a more specific test will be ordered.

Remember, your blood generally consist of 2 major parts, plasma and cellular elements. The plasma is the liquid part of your blood and allows it to flow easily. The other part consists of blood cells (red blood cells, white blood cells) and platelets. The Complete Blood Count (CBC) measures the cellular part of your blood, plus RBC indices. The RBC indices provide information about your hemoglobin content and size of your red blood cells.

The following is what your CBC will be measuring:

White blood Cells (WBC) fight infection. There are many types of WBCs and each fights infection in a special way.

Neutrophils: An important infection fighting WBC. The number your doctor looks at is your absolute neutrophil count (ANC). A healthy person has between 2,500-6,000.

Band cells: Slightly immature neutrophils.

T cells – T type lymphocytes: This WBC is of key importance to the immune system and is at the core of adaptive immunity, the system that tailors the body’s immune response to specific pathogens. They are like soldiers who search out and destroy the targeted invaders. T cell activation is measured as a way to assess the health of patients with HIV/AIDS and less frequently in other disorders.

B cells – B type lymphocytes: This WBC works chiefly by secreting antibodies into your body’s fluids. Each B cell is programmed to make one specific antibody. For example Plucky, one B cell will make an antibody that blocks a virus that causes the common cold, while another produces an antibody that attacks the bacteria that causes pneumonia. When a B cell encounters the kind of antigen that triggers it to become active, it gives rise to many large cells known as plasma cells, which produce antibodies.

Monocytes: This type of WBC develops in your bone marrow then goes into your blood, where they circulate for a few days and then go into your tissues. They then develop into one of two mature WBCs. Either dendritic or macrophages.

Eosinophils: These WBCs become active when you have certain infections from parasites, autoimmune diseases, eczema, hay fever or leukemia. Low levels indicate alcohol intoxication or over production of certain steroids such as cortisol.

Basophils: These WBCs contain the anticoagulant heparin and also histamine which promotes blood flow to tissues.

RBC Red Blood Cells carry oxygen to and carbon dioxide away from the cells in your body. The CBC measures RBCs in many ways, but the simplest measure is either Hemoglobin (Hgb)-the part of each RBC that carries iron or Hemocrit (Hct)-the percent of RBCs in the blood. When the Hgb and Hct fall too low, it’s called anemia.

MCV Mean Corpuscular (cell) Volume measures the average amount of space occupied by each RBC. A high MCV can indicate liver disease and/or alcohol abuse.

MCH Mean Corpuscular (cell) Hemoglobin measures the average amount of oxygen-carrying Hgb found in your RBCs. A high MCH can indicate anemia. Alcohol abuse can also be a contributing factor of high MCH.

MCHC Mean Corpuscular (cell) Hemoglobin Concentration. This is an Hbg/Hct ratio. A calculation of the average percentage of hemoglobin inside a RBC.

I want to add that corpuscular refers to blood cells.

RDW Red Cell Distribution Width is a measurement of the amount that RBCs vary in size. A high RDW means that your RBCs vary a lot in size. To determine a possible cause for this, a comparison is made to the MCV. One cause can be liver disease, another can be a type of anemia.

PLT Platelets help control bleeding. The medical term for platelets is thrombocytes. Platelets are produced in your bone marrow. You may bruise easily when your platelet levels are low and you may bleed even when you’re not injured. Your risk of bleeding goes up when your PLT drops below 20,000. A high or low PLT count is a sign of a blood or bone marrow disorder. A low PLT count is seen with viral infections, certain drugs such as acetaminophen, leukemia, autoimmune disorders and various other causes. Additional blood test will be required for this.

MPV Mean Platelet Value is an indicator as to whether the bone marrow is manufacturing PLTs normally. An MPV measurement can enable your doctor to detect a problem before it shows up in a PLT test.

NOTE: Your doctor may order a WBC differential test. This would include absolute neutrophil count or % neutrophil, absolute lymphocyte count or % lymphocytes etc… This is to determine the cause of abnormal results of your WBC on your CBC.

The following is what the CBC portion of your lab results might look like:

Each lab has different normal ranges and each person’s normal can vary depending on your age, gender, ethnicity and a few other things. Therefore, I did not talk about normal ranges of any test. If you fall out of your normal range, it will be clearly indicated so you will know. Usually with something like an *, an H if it’s high or an L if it’s low.

“Morgan, why do I need a blood test, I’m not sick or anything?”


“Well, a blood test tells your doctor if there is a problem before you even feel any symptoms. Early detection, in most cases, will result in a better prognosis. Do you know that I have a dear friend who was feeling fine and had a blood test that came back with a very high WBC count. This could mean she had a really bad infection or maybe even leukemia! Of course, the doctor ordered several other blood tests. All additional tests came back normal thank goodness. The doctor told her abnormally high white blood cell count could have been caused by stress in her life or even an error at the lab. Anyone can make a mistake. But, the most important thing to remember is “knowledge is power”. And, the sooner you have information about a health crisis, the better the outcome will be.”

Morgan d’ Organ