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Formed Elements and Associated Tests

Formed Elements and Associated TestsLeukocyte or White Blood Cell (WBC) CountComplete WBC count includes the total number of all types of white blood cells in a microliter of bloodNormal WBC or leukocyte counts in adults range from approximately 4.5 to 11 thousand/mm3Formed Elements and Associated TestsLeukocyte or White Blood Cell (WBC) CountElevated level usually indicates infectionIf grossly elevated, leukemia could be the cause Formed Elements and Associated TestsLeukocyte or White Blood Cell (WBC) CountLow level usually indicates a viral infection or autoimmune deficiencyExtreme bacterial infection also can destroy enough white blood cells to significantly reduce their numbersFormed Elements and Associated TestsLeukocyte or White Blood Cell (WBC) CountManual method is through use of hemocytometerMAs require further training to perform manual WBC count in a medical laboratoryFormed Elements and Associated TestsDifferential White Blood Cell CountDetermines the percentages of each type of leukocyte in a given sampleMost commonly performed by the automated analyzerFormed Elements and Associated TestsDifferential White Blood Cell CountTypes of leukocytes that are counted are neutrophils, eosinophils, basophils, lymphocytes, and monocytesResults 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 SlidesRefer 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 SlidesFIGURE 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 Wrights staining process.

PROCEDURE 48-4 (continued) Preparing SlidesFIGURE F Wrights staining process.

PROCEDURE 48-4 (continued) Preparing SlidesFIGURE G Wrights staining process.

PROCEDURE 48-4 (continued) Preparing SlidesFIGURE H Wrights staining process.

Formed Elements and Associated TestsNeutrophilsAct as the body's primary defense and make up the largest percentage of white blood cellsGranules are neutral in color on laboratory-stained slidesFormed Elements and Associated TestsNeutrophilsPhagocytosisThe process in which the neutrophil surrounds, swallows, and digests the bacteriaSegmentedMature cells with a nucleus that is divided into multiple segments connected by small thin threadsFormed Elements and Associated TestsNeutrophilsNonsegmented neutrophilsImmature cells; also called stabs or bandsNicknamed a "shift to the left" and indicates an early white blood cell responseFormed Elements and Associated TestsNeutrophilsTend to increase in response to infection; may also increase from hemorrhage, cancer, poisoning, hemolysis, and inflammationTend to decrease in response to a virus or serious bacterial infectionFIGURE 48-14 Phagocytosis. The cell engulfs and digests a bacterium.

FIGURE 48-15 Band and segmented neutrophils.

Formed Elements and Associated TestsEosinophilsWhite blood cells assumed also to be produced by the bone marrowA large number can indicate a parasitic condition or the presence of certain allergic conditionsHave granules that produce a red color on laboratory-stained slidesMake up less than 3 percent of white blood cell volumeFormed Elements and Associated TestsBasophilsThought to be produced by the bone marrow Produce heparinIncreased amounts may be found in patients who have had their spleen removed or in patients with excessive exposure to radiation.Formed Elements and Associated TestsBasophilsContain the vasodilator histamineAppear in tissues where an allergic reaction is occurringFormed Elements and Associated TestsBasophilsConcentration of basophils may contribute to the severity of allergic reactionsNormal laboratory results generally show basophils as less than 1 percent of white blood cell volume.Formed Elements and Associated TestsLymphocytesWhite blood cells produced in the bone marrow and in the lymphoid tissuePrimary function is to produce antibodies against foreign substancesSmall and large, and can proliferate into B and T cellsFormed Elements and Associated TestsLymphocytesB cells may convert into plasma cellsT cells can produce helper cells, cytotoxic cells, and suppressor cellsFormed Elements and Associated TestsLymphocytesDo not have granules and are nonsegmentedMake up the second largest volume of white blood cells, comprising 25 to 30 percentTo diagnose an individual with HIV, testing is performed to evaluate the type and amount of T cells present.Formed Elements and Associated TestsMonocytesWhite blood cells formed in the bone marrow from stem cells; assist in phagocytosisIngest foreign particles or bacteria that the neutrophils are unable to digestAssist in cleaning up cellular debris that may have been left from the infectionFormed Elements and Associated TestsMonocytesIncrease is seen in patients with tuberculosis, typhoid, and Rocky Mountain spotted feverIn a typical adult, make up 3 to 7 percent of the total white blood cell volumeFormed Elements and Associated TestsPlatelets and Coagulation StudiesPlatelets (thrombocytes): the smallest cells found in the blood; formed in the bone marrowLive for about ten days and are continuously reproducedAssist in the clotting of blood to stop bleeding or assist in healingFormed Elements and Associated TestsPlatelet CountsTypically between 150,000 and 400,000 platelets/mm3 in adultsTesting is typically performed in an outside laboratory or by automated testing.Formed Elements and Associated TestsPlatelet CountsOver 750,000 (thrombocytosis)Less than 50,000 (thrombocytopenia)Severely low counts can lead to internal bleeding and even deathFormed Elements and Associated TestsProthrombin Time (PT, Protime) International Normalized Ratio (INR)/(PT/INR)PTcoagulation test that measures the amount of time it takes to form a clotFormed Elements and Associated TestsProthrombin Time (PT, Protime) International Normalized Ratio (INR)/(PT/INR)INRStandard protocol that allows specimens performed at different laboratories to have consistent resultsDoes not reveal specific bleeding disorders in patients with liver failure or other systemic diseasesFormed Elements and Associated TestsProthrombin Time (PT, Protime) International Normalized Ratio (INR)/(PT/INR)Typically used to screen patients with symptoms of bleedingProtime for an average healthy adult will show clotting at 1014 secondsHigher than 30 seconds (or 4.5 INR) indicates a risk for bleeding; more than 40 seconds is considered criticalFormed Elements and Associated TestsProthrombin 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 syndromeFormed Elements and Associated TestsProthrombin Time (PT, Protime) International Normalized Ratio (INR)/(PT/INR)Decreased levels seen in patients with myocardial infarction, multiple myeloma, pulmonary embolus, or thrombophlebitisFormed Elements and Associated TestsPartial Thromboplastin Time (PTT)Determines the length of time it takes for a fibrin clot to formCan help to determine which specific clotting factors are affectedCommonly used to determine the effectiveness of anticoagulant therapyFormed Elements and Associated TestsPartial Thromboplastin Time (PTT)Helps to screen for bleeding tendencies and identify more precise causesNormal findings are typically 6070 seconds.Other Blood TestsCommon panels include the lipid panel and the liver panelLipid panelCholesterol, triglycerides, and high-density lipoproteins (HDL)Liver panelSGOT and SGPTCBCCoagulation studiesOther Blood TestsRefer to the following tables in the student text:Table 48-1: Common Blood Test GroupsTable 48-2: Common Laboratory Tests and Their Normal Values Table 48-3: Common Blood Chemistry TestsTABLE 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 TestsComprehensive Metabolic Panel (CMP)Screening tool used to:Evaluate organ functionCheck for common disordersMonitor the progress of current conditions and response to medicationsIncludes 14 essential tests included among the basic metabolic panel, renal panel, liver function tests, and electrolytesOther Blood TestsComprehensive Metabolic Panel (CMP)Abnormality in any area may indicate a need for further, more-specific testingRecommended that the patient fast for 12 hours before testingNormal values can be found in Table 48-3 Common Blood Chemistry TestsOther Blood TestsGlucoseA simple sugar required by all body cells to produce energy; circulates in the blood Used to give energy to the cellsOther Blood TestsGlucoseHyperglycemiaWhen glucose cannot get into the cells for consumption, it builds up in the blood and clogs up the organsCritical, life-threatening levels above 700 mg/dL while fasting Other Blood TestsGlucoseHypoglycemia (low blood sugar)Can happen rapidly and can become lethal before treatment may be consideredSuspected blood glucose abnormalities are always treated as if they are low, until blood testing can be performed.

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