CBC Test: White Blood Cells

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  • 0:37 Leukopenia & Leukocytosis
  • 1:45 Neutrophilia
  • 3:45 Lymphocytosis
  • 4:25 Elevations & Decreases
  • 6:32 Amount of Change Matters
  • 7:15 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson will discuss the white blood cell count, which cells comprise it, and what important things may cause their levels to elevate or decrease. We'll also cover something known as a left shift.

Defending Your Body

The defenders of freedom! The defenders of the helpless! They are not Martin Luther King, George Washington or the Dalai Lama. They are the white blood cells in your body. They are your knights in shining armor. Without them you would be helpless and you wouldn't be free to do much of anything but live in a protective bubble.

That's why we'll take a look at how doctors watch for abnormal increases or decreases in their numbers within your body using blood tests.

Leukopenia and Leukocytosis

Many different values can be found on an important blood test, called a complete blood count. Some of these values pertain to your white blood cells.

One value is shortened as WBC. It stands for white blood cells. The normal white blood cell count in a person's body is approximately 4,000 to 11,000 cells per microliter. An abnormal elevation in the white blood cell count is called leukocytosis, and an abnormal decrease in the white blood cell count is termed leukopenia.

Leuko- stands for white in white blood cells, while -penia is the Greek word for poverty or deficiency of something. It'll be important to remember that little tidbit for later.

The white blood cell count is made up of the total count of many different white blood cells, including: neutrophils, lymphocytes, monocytes, eosinophils and basophils.

The majority of the count is made up of neutrophils, and that is what we'll focus in on the most right now.

Neutrophilia and Neutropenia

It is safe to say that leukocytosis most commonly occurs as a result of neutrophilia, which is an abnormally increased amount of neutrophils. Keep the following general reasons in mind for why neutrophilia may occur:

  • Infection, especially bacterial infection
  • Inflammation, especially increased in acute inflammation, more so than other leukocytes
  • Stress
  • Cancer
  • Drugs
  • And more

Do note that infection and inflammation can go hand in hand, but inflammation does not have to be infectious in origin as in the case of an autoimmune disease.

What's also important to know is how severe the elevation or decrease is and when it occurs. As an interesting tidbit, during a bacterial infection, bacterial endotoxins initially cause an abnormally low neutrophil count, called neutropenia. Recall that -penia refers to poverty or lack of something. However, within a few hours, neutrophilia will result. The details of why this occurs are interesting, but we just don't have the time for it in this lesson.

But I will indulge you in another interesting concept known as a left shift instead. If you ever hear this term, this means that the bone marrow is releasing a lot more immature neutrophils, called band neutrophils, to go join the fight against some kind of trigger of inflammation, such as bacteria. The baby band cells (the immature baby neutrophils) are released prematurely because there is a high demand for them to go join the fight since the mature soldiers are already dying in droves in the thick of the fight. It's essentially a sign there is something really wrong in the body, because no one in their right mind would want poor little baby band cells to go into a warzone!

Neutrophils are the frontline troops involved in your protection. They are like the common and numerous privates in an army, selflessly running towards the front lines to defend you.

Important Causes of Lymphocytosis

Thankfully neutrophils - band neutrophils or not - aren't alone in their fight for your freedom, health, and prosperity. Another white blood cell that is part of the leukocyte count is known as a lymphocyte. An abnormal increase of lymphocytes, or lymphocytosis, is generally attributed to:

  • Viral infections
  • Chronic, or long standing, inflammatory diseases or infections
  • Cancer, such as chronic lymphocytic leukemia and acute lymphoblastic leukemia

Lymphocytes are like the army engineers in your private army. They provide your body with highly specialized responses and products for specific problems.

Elevations of Other Leukocytes

The major or most important reasons for abnormal elevations in other white blood cells include:

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