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

Formed Elements and Associated Tests

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

the cause

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

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

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

automated analyzer

Formed Elements and Associated Tests

• 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.

PROCEDURE 48-4 (continued) Preparing

SlidesFIGURE C Blood smear.

PROCEDURE 48-4 (continued) Preparing

SlidesFIGURE D Blood smear.

PROCEDURE 48-4 (continued) Preparing

SlidesFIGURE E Wright’s

staining process.

PROCEDURE 48-4 (continued) Preparing

SlidesFIGURE F Wright’s

staining process.

PROCEDURE 48-4 (continued) Preparing

SlidesFIGURE G Wright’s

staining process.

PROCEDURE 48-4 (continued) Preparing

SlidesFIGURE H Wright’s

staining process.

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

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

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

Formed Elements and Associated Tests

• 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.

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

• 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.

Formed Elements and Associated Tests

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

reaction is occurring

Formed Elements and Associated Tests

• 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.

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

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

cytotoxic cells, and suppressor cells

Formed Elements and Associated Tests

• 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.

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

• 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.

Formed Elements and Associated Tests

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

bleeding and even death

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

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

myocardial infarction, multiple myeloma, pulmonary embolus, or thrombophlebitis

Formed Elements and Associated Tests

• 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

Formed Elements and Associated Tests

• 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

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.