Absolute Neutrophil Counts (ANCs) - A Mandatory Requirement for Monitoring Patients Taking FazaClo (clozapine, USP) Orally Disintegrating Tablets

This brief tutorial is designed to help assure a uniform level of understanding of Absolute Neutrophil Counts (ANCs). We will first define neutrophils in the context of all the major types of blood cells. Then, we will demonstrate exactly how to calculate the Absolute Neutrophil Count.

Since Neutrophils are a special type of white blood cell, and since we know that there are both red and white blood cells, we will start there, with a rudimentary overview, comparing the principal functions of both red blood cells (RBCs) and white blood cells (WBCs).

Red and White Blood Cells: General Background

Red Blood Cells (also known as ‘erythrocytes’)

• Red blood cells perform very important functions: delivering oxygen and removing waste. Therefore, red blood cells are absolutely essential for life.

• Red blood cells are red because they contain a protein called hemoglobin which is bright red in color. As blood passes through the lungs, oxygen molecules attach to the hemoglobin, making it an excellent vehicle for delivering oxygen and carrying away carbon dioxide.

• As blood moves away from the lungs and heart and then through the circulatory system, the hemoglobin releases oxygen to the cells. The empty hemoglobin molecules then bond with the tissue's carbon dioxide and other waste gases, transporting them safely away.
  

White Blood Cells (also known as ‘leukocytes’)

• White blood cells are an essential part of the body’s immune system, protecting you from germs and other foreign invaders.

• There are several specialized types of white blood cells, and among these neutrophils are the principal infection fighters. Neutrophils go by several aliases, including the tongue-twister ‘polymorphonuclear cells’, as well as ‘granulocytes’; they are also called ‘segmented cells’ or simply ‘segs’. When these show up in blood tests as immature cells they are called ‘banded cells’ or simply ‘bands’.

• Technically, the granulocytes or neutrophils are considered the total of segs + bands, but bands are usually so few in number that they may go unreported.

Red and White Cells in a Blood Sample

This microscopic view reveals that there are many more RBCs (red spheres) than WBCs (stained blue). In the center of the field, one ‘band’ neutrophil (immature) is seen on the left and one segmented neutrophil (mature) is seen on the right.

Major classes of diseases related to white blood cell abnormalities in general include:

• Leukemia: Too many white blood cells (which crowd out red blood cells and deprive the body of oxygen).

• Leukopenia: Too few white blood cells (which leave the person vulnerable to many kinds of infection).

Red and White Blood Cells -- Too Many or Too Few?

• Red blood cell count (RBC): This is the number of red blood cells in one cubic millimeter (also mm³ or cmm) of blood. Normal ranges vary slightly between laboratories, usually between 4 to 6 million cells/mm³.

• Hemoglobin (Hb): Hemoglobin is the protein molecule within red blood cells that carries oxygen and gives blood its red color. Normally hemoglobin levels are lower in women than in men.

• White blood cell count (WBC): This is the number of white blood cells in one cubic millimeter of blood. Normal ranges vary slightly between laboratories but are generally between 4 – 10 thousand/mm³. This can be referred to also as the leukocyte count and is often expressed in whole numbers, i.e., 4,000 to 10,000. However, in mathematical shorthand notation, these same numbers may be expressed either as 4.0 - 10.0 x 1000 or 4.0(10³) – 10.0(10³). These are simply different ways of stating the same numbers. However, the laboratory will break down the total WBC into its major sub-types by performing the ‘differential count’.

• Differential count: There are six major types of white blood cells. Here, we are interested primarily in neutrophils, but a complete white blood cell test differentiates among the various white blood cells: neutrophils, lymphocytes, monocytes, bands, eosinophils, and basophils. Test results report the percentages of each of these different types of white blood cells. These percentages will total to 100%. Next is a list of the average percentages of each in a typical differential count:

• The Absolute Neutrophil Count (ANC) translates the percentage of neutrophils (usually between 50% and 60%) into an actual number of cells.

Absolute Neutrophil Count: Clinical Significance

Physicians know from experience that a certain minimum number of neutrophils must be circulating in every drop of your blood to prevent infections from developing. Without these infection fighters constantly on the job, you would not only get sick, you would get very sick and possibly die because infection would simply take over.

Physicians get concerned when the ANC drops below 2000, and they get very worried when the ANC drops below 1000. At that point you are very likely going to be admitted to the hospital and placed in isolation to keep your family and friends from inadvertently spreading germs that your body can no longer fight off. This is a potentially life-threatening condition.

Absolute Neutrophil Count: Calculation

Example 1. Normal ANC
The laboratory tests for Jack Jones show a total WBC count of 6800 (reported by the lab as 6.8). Jack’s differential count shows that he has 58% neutrophils. To get the Absolute Neutrophil Count take 58% of 6800. Jack’s ANC is 3944. On a calculator this is done most easily by multiplying 6800 by .58

Example 2. Neutropenia aka Granulocytopenia (Low neutrophils) – Danger Signal
Sarah Smith’s total WBC is 5200, and her differential count shows 38% neutrophils. What is her ANC and what does it mean? Her ANC is 1976 (5200 x .38). This is below 2000 and provides a warning to the doctor that Ms. Smith needs to be watched closely, since her infection-fighting ability may be impaired. She is not necessarily in trouble right now, but may be susceptible to infection, and could become sick.

Example 3. Agranulocytosis (Neutrophils very low or absent) – Life-Threatening
Ben Brown came into the ER with a high fever and sore throat. WBC and differential showed a Total WBC of 3800, with 12% neutrophils. How serious is his condition? VERY serious. Ben’s ANC is 456 (3800 x .12). He is already experiencing very significant clinical signs of illness (fever and sore throat). He will get very much worse unless help can be provided quickly. Nowadays, there are excellent medicines to use in the hospital that help raise neutrophil levels to the point where they can once again protect the body. But, these kinds of medical crises must not be overlooked.

The FazaClo ANC Calculator

To make the job of calculating ANCs a little easier, the FazaClo website includes a convenient ANC calculator. Click on the following link for the calculator: ANC Calculator. – we think you will find this a useful tool. We hope this tutorial has been helpful.