A complete blood count (CBC), also known as full blood count (FBC) or full blood exam (FBE) or blood panel, is a test 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. A complete blood count (CBC) gives important information about the kinds and numbers of cells in the blood, especially red blood cells, white blood cells, and platelets. A CBC helps your health professional check any symptoms, such as weakness, fatigue, or bruising, you may have. A CBC also helps him or her diagnose conditions, such as anemia, infection, and many other disorders.Counting and examining blood cells are very important in the diagnosis of blood cell diseases. Blood cell counts are used during diagnosis, treatment and follow up to determine the health of the patient. Blood cell counts alone cannot determine if a patient has a blood cancer. However, blood cell counts can alert the physician if further testing is needed. (Esterling et al 1994).                                           Alexander Vastem is widely regarded as being the first person to use the complete blood count for clinical purposes.  Reference ranges used today stem from his clinical trials in the early 1960s. The cells that circulate in the bloodstream are generally divided into three types: white blood cells (leukocytes), red blood cells (erythrocytes), and platelets (thrombocytes). (Fiatarone et al 1989)

AIMS AND OBJECTIVES

 The Aim and Objective of this study is:

 – To check how the body is dealing with some types of stress.

– To screen for high and low value before and after work.

-To check how abnormal stress is affecting the blood cells and count.

 

 

 

 

CHAPTER TWO

LITERATURE REVIEW

2.1    HISTORY OF COMPLETE BLOOD COUNT

Alexander Vastem is widely regarded as being the first person to use the complete blood count for clinical purposes.[citation needed] Reference ranges used today stem from his clinical trials in the early 1960s. The cells that circulate in the bloodstream are generally divided into three types: white blood cells (leukocytes), red blood cells (erythrocytes), and platelets (thrombocytes). Abnormally high or low counts may indicate the presence of many forms of 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. A CBC is routinely performed during annual physical examinations in some jurisdictions.(Ho et al 1995)

2.2    SAMPLES                                                                                         A phlebotomist collects the specimen; in this case blood is drawn in a test tube containing an anticoagulant (EDTA, sometimes citrate) to stop it from clotting, and transported to a laboratory.      In the past, counting the cells in a patient’s blood was performed manually, by viewing a slide prepared with a sample of the patient’s blood under a microscope (a blood film, or peripheral smear). Nowadays, this process is generally automated by use of an automated analyzer, with only approximately 30% samples now being examined manually. (Hirase et al 1992)

2.3    AUTOMATED BLOOD COUNT

The blood is well mixed (though not shaken) and placed on a rack in the analyzer. This instrument has many different components to analyze different elements in the blood. The cell counting component counts the numbers and types of different cells within the blood. The results are printed out or sent to a computer for review. (Shimizut et al 1985)                                                     Blood counting machines aspirate a very small amount of the specimen through narrow tubing. Within this tubing, there are sensors that count the number of cells going through it, and can identify the type of cell; this is flow cytometry. The two main sensors used are light detectors, and electrical impedance. One way the instrument can tell what type of blood cell is present is by size. Other instruments measure different characteristics of the cells to categorize them. Because an automated cell counter samples and counts so many cells, the results are very precise. However, certain abnormal cells in the blood may be identified incorrectly, and require manual review of the instrument’s results and identifying any abnormal cells the instrument could not categorize. (Wood et al 1999)                                                                         In addition to counting, measuring and analyzing red blood cells, white blood cells and platelets, automated hematology analyzers also measure the amount of hemoglobin in the blood and within each red blood cell. This information can be very helpful to a physician who, for example, is trying to identify the cause of a patient’s anemia. If the red cells are smaller or larger than normal, or if there’s a lot of variation in the size of the red cells, this data can help guide the direction of further testing and expedite the diagnostic process so patients can get the treatment they need quickly. (Vogelaar et al 2002)

2.4    Manual Blood Count

Counting chambers that hold a specified volume of diluted blood (as there are far too many cells if it is not diluted) are used to calculate the number of red and white cells per litre of blood. To identify the numbers of different white cells, a blood film is made, and a large number of white cells (at least 100) are counted. This gives the percentage of cells that are of each type. By multiplying the percentage with the total number of white blood cells, the absolute number of each type of white cell can be obtained. (Gulati et al 2002)           The advantage of manual counting is that automated analysers are not reliable at counting abnormal cells. That is, cells that are not present in normal patients and are only seen in the peripheral blood with certain haematological conditions. Manual counting is subject to sampling error because so few cells are counted compared with automated analysis.  Medical technicians examine blood film via a microscope for 30% of CBCs, not only to find abnormal white cells, but also because variation in the shape of red cells is an important diagnostic tool. Although automated analyzers give fast, reliable results regarding how many red cells, the average size of the red cell, and the variation in size of the red cells, they don’t detect cells’ shapes. Also, some normal patients’ platelets will clump in EDTA anticoagulated blood, which causes automatic analysers to give a falsely low platelet count. The technician viewing the slide in these cases will see clumps of platelets and can estimate if there are low, normal, or high numbers of platelets. (Knuston et al 1999)

2.5    WHITE CELL BLOOD COUNT                                                           Alternative Names: Leukocyte count; White blood cell count. A WBC count is a blood test to measure the number of white blood cells (WBCs). White blood cells help fight infections. They are also called leukocytes. There are five major types of white blood cells:

  • Basophils
  • esinophils
  • Lymphocytes (T cells and B cells)
  • Monocytes
  • Neutrophils (Hogman et al 1999)

2.5.1How the Test Is Performed

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood. Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding. In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding. The blood sample is sent to a laboratory. A WBC count is almost always done as part of a complete blood count (CBC).

2.5.2How to Prepare For the Test                                                                               No special preparation is usually needed. Tell your doctor about any medications you are taking, including over-the-counter products. Certain drugs may interfere with test results.Drugs that may increase WBC counts include:

  • Allopurinol
  • Aspirin
  • Chloroform
  • Corticosteroids
  • Epinephrine
  • Heparin
  • Quinine
  • Triamterene

Drugs that may lower your WBC count include:

  • Antibiotics
  • Anticonvulsants
  • Antihistamines
  • Antithyroid drugs
  • Arsenicals
  • Barbiturates
  • Chemotherapy drugs
  • Diuretics
  • Sulfonamides.

2.5.3Why the Test Is Performed

Your doctor will order this test to find out how many white blood cells you have. Your body produces more white blood cells when you have an infection or allergic reaction – even when you are under general stress. (Vogelaar et al 2002)

2.5.4Normal Values

4,500-10,000 white blood cells per microlitre (mcL). (Shortland et al 1997)

Note: Normal value ranges may vary slightly among different laboratories.

2.5.5What Abnormal Results Mean

A low number of WBCs is called leukopenia. It may be due to:

  • Bone marrow failure (for example, due to infection, tumor, or abnormal scarring)
  • Collagen-vascular diseases (such as lupus erythematosus)
  • Disease of the liver or spleen
  • Radiation therapy or exposure

A high number of WBCs is called leukocytosis. It may be due to:

  • Anemia
  • Infectious diseases
  • Inflammatory disease (such as rheumatoid arthritis or allergy)
  • Leukemia
  • Severe emotional or physical stress
  • Tissue damage (for example, burns)

What the Risks Are

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

  • Excessive bleeding
  • Fainting or feeling light-headed
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken) (George et al 1986)

2.5.6Special Considerations

People who have had their spleen remove (splenectomy) will always have a slightly higher number of WBCs.

2.6    RED BLOOD CELL COUNTS                                                           Alternative Names: Erythrocyte count; Red blood cell count                        An RBC count is a blood test that tells how many red blood cells (RBCs) you have.RBCs contain hemoglobin, which carries oxygen. How much oxygen your body tissues get depends on how many RBCs you have and how well they work.

2.6.1How the Test Is Performed                                                              Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding. In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

2.6.2How to Prepare For the Test                                                            No special preparation is necessary for adults.

2.6.3Why the Test Is Performed                                                              The RBC count is almost always part of the CBC (complete blood count) test.The test can help diagnose anemia and other conditions affecting red blood cells.Additional conditions under which an RBC count may be performed:

  • Alport syndrome
  • Drug-induced immune hemolytic anemia
  •  Haemolytic anaemia due to G6PD defficency
  • Hereditary anemias, such as thalassemia
  • Idiopathic autoimmune haemolytic disease
  • Immune haemolytic anaemia

2.6.4Normal Values; The general the range is as follows:                Male: 4.7 to 6.1 million cells per microlitre (cells/mcL)                    Female: 4.2 to 5.4 million cells/mcL (Shortland et al 1997)

Note: Normal value ranges may vary slightly among different laboratories.

2.6.5What Abnormal Results Mean

Higher-than-normal numbers of RBCs may be due to:

  • Cigarette smoking
  • Congenital heart disease
  • Cor pulmonale
  • Dehydration (such as from severe diarrhea)
  • Kidney tumor (renal cell carcinoma)
  • Low blood oxygen levels (hypoxia)
  • Pulmonary fibrosis
  • Polycythaemia vera

Your RBC count will increase for several weeks when you move to a higher altitude.

2.6.6Drugs that can increase the RBC count include:

  • Gentamicin
  • Methyldopa

Lower-than-normal numbers of RBCs may be due to;

  • Bone marrow failure (for example, from radiation, toxins, or tumor)
  • Erythropoietin deficiency (secondary to kidney disease)
  • Haemolysis (RBC destruction) due to transfusion, blood vessel injury, or other cause
  • Hemorrhage (bleeding)
  • Leukemia
  • Malnutrition
  •  Multiple myeloma
  • Nutritional deficiencies of:
    • Iron
    • Copper
    • Folate
    • Vitamin B-12
    • Vitamin 6
  • Over hydration
  • Pregnancy
  • Anaemia

2.6.7Drugs that can decrease the RBC count include:

  • Chemotherapy drugs
  • Chloramphenicol
  • Hydantoins
  • Quinidine

What the Risks Are

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

  • Excessive bleeding
  • Fainting or feeling light-headed
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken) (George et al 1986)

2.7    DIFFERENTIAL COUNT

Alternative Names: Differential; White blood cell differential count

The blood differential test measures the percentage of each type of white blood cell (WBC) that you have in your blood. It also reveals if there are any abnormal or immature cells

2.7.1How the Test Is Performed

The health care provider will take blood from your vein. The blood collects into an airtight container. In infants or a young child, blood will be taken from a heel stick or finger stick. The blood is collected in a small glass tube or onto a slide or test strip.   Cotton or a bandage may be applied to stop any bleeding.

A laboratory specialist takes a drop of blood from your sample and smears it onto a glass slide. The smear is stained with a special dye, which helps tell the difference between various types of white blood cells.

Five types of white blood cells, also called leukocytes, normally appear in the blood:

v  Neutrophils

v  Lymphocytes (B cells and T cells)

v  Monocytes

v  Eosinophils

v  Basophils                                                            

A computer or the health care provider counts the number of each type of cell. The test shows if the number of cells is in proper proportion with one another, and if there is more or less of one cell type.

2.7.2How to Prepare For the Test                                       

No special preparation is necessary.

2.7.3Why The Test Is Performed                                                             This test is done to diagnose an infection, anemia, and leukemia. It may also be used to see if treatment for any of these conditions is working.

2.7.3Normal Values                                                              

* Neutrophils: 40% to 60%                                                      

* Lymphocytes: 20% to 40%

* Monocytes: 2% to 8%

* Eosinophils: 1% to 4%

* Basophils: 0.5% to 1%

* Band (young neutrophil): 0% to 3% (Shortland et al 1997)

2.7.4What Abnormal Results Mean                                                         Any infection or acute stress increases your number of white blood cells. High white blood cell counts may be due to inflammation, an immune response, or blood diseases such as leukemia. It is important to realize that an abnormal increase in one type of white blood cell can cause a decrease in the percentage of other types of white blood cells.                                                      An increased percentage of neutrophils may be due to:                       * Acute infection                                                                                * Eclampsia                                                                                        * Gout                                                                                               * Myelocytic leukemia                                                                             * Rheumatoid arthritis                                                                      * Rheumatic fever                                                                              * Acute stress                                                                             * Thyroiditis                                                                                                * Trauma

A decreased percentage of neutrophils may be due to:

    * Aplastic anemia

    * Chemotherapy

    * Influenza

    * Widespread bacterial infection

    * Radiation therapy or exposure

An increased percentage of lymphocytes may be due to:

    * Chronic bacterial infection

    * Infectious hepatitis

    * Infectious mononucleosis

    * Lymphocytic leukemia

    * Multiple myeloma

    * Viral infection (such as infectious mononucleosis, mumps, measles)

    * Recovery from a bacterial infection

A decreased percentage of lymphocytes may be due to

    * Chemotherapy

    * HIV infection

    * Leukemia

    * Radiation therapy or exposure

    * Sepsis

An increased percentage of monocytes may be due to

    * Chronic inflammatory disease

    * Parasitic infection

    * Tuberculosis

    * Viral infection (for example, infectious mononucleosis, mumps, measles)

An increased percentage of eosinophils may be due to:

    * Allergic reaction

    * Cancer

    * Parasitic infection

    * Hodgkin’s disease

A decreased percentage of basophils may be due to:

    * Acute allergic reaction

What the Risks Are

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

    * Excessive bleeding

    * Fainting or feeling light-headed

    * Hematoma (blood accumulating under the skin)

    * Infection (a slight risk any time the skin is broken) (George et al 1986)

2.8    PLATELET COUNT                                                                           Alternative name: Thrombocyte count

A platelet count is a test to measure how many platelets you have in your blood. Platelets help the blood clot. They are smaller than red or white blood

2.8.1How the Test Is Performed

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.  Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.                                                                                 Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.                                      In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding. (Qi et al 2001)

2.8.2How To Prepare For The Test                                                No preparation is necessary. Tell your doctor if you are taking any medications, including over-the-counter medicines and supplements. Drugs that can lower platelet counts include chemotherapy drugs, chloramphenicol, colchicine, H2 blocking agents, heparin, hydralazine, indomethacin, isoniazid, quinidine, streptomycin, sulfonamide, thiazide diuretic, and tolbutamide. (Zhang et al 2004)

2.8.3Why the Test Is Performed

The number of platelets in your blood can be affected by many diseases. Platelets may be counted to monitor or diagnose diseases, or identify the cause of excess bleeding.

 

 

2.8.4Normal Values                                                    

150,000 to 400,000 platelets per microliter (mcL)                            

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results. (Shortland et al 1997)

2.8.5What Abnormal Results Mean

If the number of platelets is below normal (thrombocytopenia), the cause may be:

    * Cancer chemotherapy

    * Disseminated intravascular coagulation (DIC)

    * Hemolytic anemia

    * Hypersplenism

    * Idiopathic thrombocytopenic purpura (ITP)

    * Leukemia

    * Massive blood transfusion

    * Prosthetic heart valve

If the number is higher than normal (thrombocytosis), the cause may be:

    * Anemia

    * Certain types of cancer

    * Early chronic myelogenous leukemia (CML)

    * Polycythemia vera

    * Primary thrombocytosis

    * Recent spleen removal (Uchida et al 2004)

What the Risks Are

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

    * Excessive bleeding

    * Fainting or feeling light-headed

    * Hematoma (blood accumulating under the skin)

    * Infection (a slight risk any time the skin is broken) (George et al 1986)

The CBC test also provides information about the following measurements:

    * Average red blood cell size (MCV)

    * Hemoglobin amount per red blood cell (MCH)

    * The amount of hemoglobin relative to the size of the cell (hemoglobin concentration) per red blood cell (MCHC)