Download - Formed Elements and Associated Tests Leukocyte or White Blood Cell (WBC) Count – Complete WBC count includes the total number of all types of white blood

Formed Elements and Associated Tests

• Leukocyte or White Blood Cell (WBC) Count– Complete WBC count includes the total

number of all types of white blood cells in a microliter of blood

– Normal WBC or leukocyte counts in adults range from approximately 4.5 to 11 thousand/mm3


• Leukocyte or White Blood Cell (WBC) Count– Elevated level usually indicates infection– If grossly elevated, leukemia could be

the cause


• Leukocyte or White Blood Cell (WBC) Count– Low level usually indicates a viral

infection or autoimmune deficiency– Extreme bacterial infection also can

destroy enough white blood cells to significantly reduce their numbers


• Leukocyte or White Blood Cell (WBC) Count–Manual method is through use of

hemocytometer–MAs require further training to perform

manual WBC count in a medical laboratory


• Differential White Blood Cell Count– Determines the percentages of each

type of leukocyte in a given sample–Most commonly performed by the

automated analyzer


• Differential White Blood Cell Count– Types of leukocytes that are counted are

neutrophils, eosinophils, basophils, lymphocytes, and monocytes

– Results may be read as percentages or as numbers in a given quantity depending on the laboratory and equipment being used.

FIGURE 48-12 For a differential white blood cell count, (A) the slide is examined under oil immersion. (B) Cells are viewed using a bright light and 100× magnification.

FIGURE 48-13 Types of white blood cells.

Preparing Slides

• Refer to Procedure 48-4: Preparing Slides for details about this technique.

• MAs require further training to perform this test in a medical laboratory; it is commonly performed in an educational setting to further understanding.

PROCEDURE 48-4 Preparing Slides

FIGURE A Blood smear.

PROCEDURE 48-4 (continued) Preparing

SlidesFIGURE B Blood smear.


SlidesFIGURE C Blood smear.


SlidesFIGURE D Blood smear.


SlidesFIGURE E Wright’s

staining process.


SlidesFIGURE F Wright’s

staining process.


SlidesFIGURE G Wright’s

staining process.


SlidesFIGURE H Wright’s

staining process.


• Neutrophils– Act as the body's primary defense and

make up the largest percentage of white blood cells

– Granules are neutral in color on laboratory-stained slides


• Neutrophils– Phagocytosis• The process in which the neutrophil

surrounds, swallows, and digests the bacteria

– Segmented• Mature cells with a nucleus that is divided

into multiple segments connected by small thin threads


• Neutrophils– Nonsegmented neutrophils• Immature cells; also called stabs or bands

– Nicknamed a "shift to the left" and indicates an early white blood cell response


• Neutrophils– Tend to increase in response to

infection; may also increase from hemorrhage, cancer, poisoning, hemolysis, and inflammation

– Tend to decrease in response to a virus or serious bacterial infection

FIGURE 48-14 Phagocytosis. The cell engulfs and digests a

bacterium.

FIGURE 48-15 Band and segmented neutrophils.


• Eosinophils–White blood cells assumed also to be

produced by the bone marrow– A large number can indicate a parasitic

condition or the presence of certain allergic conditions

– Have granules that produce a red color on laboratory-stained slides

–Make up less than 3 percent of white blood cell volume


• Basophils– Thought to be produced by the bone

marrow – Produce heparin– Increased amounts may be found in

patients who have had their spleen removed or in patients with excessive exposure to radiation.


• Basophils– Contain the vasodilator histamine– Appear in tissues where an allergic

reaction is occurring


• Basophils– Concentration of basophils may

contribute to the severity of allergic reactions

– Normal laboratory results generally show basophils as less than 1 percent of white blood cell volume.


• Lymphocytes–White blood cells produced in the bone

marrow and in the lymphoid tissue– Primary function is to produce

antibodies against foreign substances– Small and large, and can proliferate into

B and T cells


• Lymphocytes– B cells may convert into plasma cells– T cells can produce helper cells,

cytotoxic cells, and suppressor cells


• Lymphocytes– Do not have granules and are

nonsegmented–Make up the second largest volume of

white blood cells, comprising 25 to 30 percent

– To diagnose an individual with HIV, testing is performed to evaluate the type and amount of T cells present.


• Monocytes–White blood cells formed in the bone

marrow from stem cells; assist in phagocytosis

– Ingest foreign particles or bacteria that the neutrophils are unable to digest

– Assist in cleaning up cellular debris that may have been left from the infection


• Monocytes– Increase is seen in patients with

tuberculosis, typhoid, and Rocky Mountain spotted fever

– In a typical adult, make up 3 to 7 percent of the total white blood cell volume


• Platelets and Coagulation Studies– Platelets (thrombocytes): the smallest

cells found in the blood; formed in the bone marrow

– Live for about ten days and are continuously reproduced

– Assist in the clotting of blood to stop bleeding or assist in healing


• Platelet Counts– Typically between 150,000 and 400,000

platelets/mm3 in adults– Testing is typically performed in an

outside laboratory or by automated testing.


• Platelet Counts– Over 750,000 (thrombocytosis)– Less than 50,000 (thrombocytopenia)– Severely low counts can lead to internal

bleeding and even death


• Prothrombin Time (PT, Protime) International Normalized Ratio (INR)/(PT/INR)– PT• coagulation test that measures the amount

of time it takes to form a clot


• Prothrombin Time (PT, Protime) International Normalized Ratio (INR)/(PT/INR)– INR• Standard protocol that allows specimens

performed at different laboratories to have consistent results• Does not reveal specific bleeding disorders

in patients with liver failure or other systemic diseases


• Prothrombin Time (PT, Protime) International Normalized Ratio (INR)/(PT/INR)– Typically used to screen patients with

symptoms of bleeding– Protime for an average healthy adult will

show clotting at 10–14 seconds– Higher than 30 seconds (or 4.5 INR)

indicates a risk for bleeding; more than 40 seconds is considered critical


• Prothrombin Time (PT, Protime) International Normalized Ratio (INR)/(PT/INR)– Elevated levels seen in patients with

severe bone marrow depression, cancer, liver or collagen diseases, pancreatitis, disseminated intravascular coagulation, and toxic shock syndrome


• Prothrombin Time (PT, Protime) International Normalized Ratio (INR)/(PT/INR)– Decreased levels seen in patients with

myocardial infarction, multiple myeloma, pulmonary embolus, or thrombophlebitis


• Partial Thromboplastin Time (PTT)– Determines the length of time it takes

for a fibrin clot to form– Can help to determine which specific

clotting factors are affected– Commonly used to determine the

effectiveness of anticoagulant therapy


• Partial Thromboplastin Time (PTT)– Helps to screen for bleeding tendencies

and identify more precise causes– Normal findings are typically 60–70

seconds.

Other Blood Tests

• Common panels include the lipid panel and the liver panel

• Lipid panel– Cholesterol, triglycerides, and high-

density lipoproteins (HDL)

• Liver panel– SGOT and SGPT

• CBC• Coagulation studies

Other Blood Tests

• Refer to the following tables in the student text:– Table 48-1: Common Blood Test Groups– Table 48-2: Common Laboratory Tests

and Their Normal Values – Table 48-3: Common Blood Chemistry

Tests

TABLE 48-1 Common Blood Test

Groups

TABLE 48-2 Common

Laboratory Tests and

Their Normal Values

TABLE 48-3 Common

Blood Chemistry

Tests

TABLE 48-3 (continued)

Common Blood

Chemistry Tests

Other Blood Tests

• Comprehensive Metabolic Panel (CMP)– Screening tool used to:• Evaluate organ function• Check for common disorders• Monitor the progress of current conditions

and response to medications

– Includes 14 essential tests included among the basic metabolic panel, renal panel, liver function tests, and electrolytes

Other Blood Tests

• Comprehensive Metabolic Panel (CMP)– Abnormality in any area may indicate a

need for further, more-specific testing– Recommended that the patient fast for

12 hours before testing– Normal values can be found in Table 48-

3 Common Blood Chemistry Tests

Other Blood Tests

• Glucose– A simple sugar required by all body cells

to produce energy; circulates in the blood

– Used to give energy to the cells

Other Blood Tests

• Glucose– Hyperglycemia• When glucose cannot get into the cells for

consumption, it builds up in the blood and clogs up the organs

– Critical, life-threatening levels above 700 mg/dL while fasting

Other Blood Tests

• Glucose– Hypoglycemia (low blood sugar)• Can happen rapidly and can become lethal

before treatment may be considered

– Suspected blood glucose abnormalities are always treated as if they are low, until blood testing can be performed.

Download - Formed Elements and Associated Tests Leukocyte or White Blood Cell (WBC) Count – Complete WBC count includes the total number of all types of white blood

Top Related