Chapter 5 Hematology – Flashcards
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What is Hematology?
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the study of the cellular components of the bloodstream and bone marrow.
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What is a hematologist?
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Someone who primarily studies the cellular elements of the blood and also investigates the hemostasis of the blood. (its ability to initiate or stop the clotting process).
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The ___________ is a routine, moderately complex test ordered to evaluate health status.
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CBC (Complete Blood Count)
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What color top tube does a CBC require?
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Lavender top
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What are formed Elements?
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the solid parts of the blood such as RBCs, WBCs, and platelets that can be seen under a microscope.
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The formed elements are suspended in a watery liquid called _________, which contains hundreds of dissolved biochemical substances such as hormones, vitamins, albumin, and clotting factors.
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Plasma
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Where are blood cells produced?
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Red Bone Marrow (which is found in flat bones at the ends of long bones)
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All blood cells originate from a ________ able to differentiate (change) into any of the seven visible blood elements found in circulating blood.
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Hemocytoblast
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What is an immature erythrocyte called? there are 2 things it can be called.
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Erythroblast or a rubriblast
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A normal RBC, which sheds its nucleus before entering the bloodstream, is called a _______.
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Normocyte
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The last stage in RBC development immediately before a mature RBC enters the bloodstream is a _________.
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Reticulocyte
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Mature RBCs contain millions of _______ ________ that have a reddish pigment and are capable of carrying oxygen.
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Hemoglobin molecules
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What happens to a RBC after it dies?
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RBCs disintegrate and release their iron portion, heme, and their protein portion, glob in, which is sent to the live as bilirubin, which is further metabolized in the liver, intestines, and kidneys.
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What is the test used to tell the percentage of each of the 5 different types of WBCs and also scan RBCs and pits?
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A WBC differential.
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How do you collect the blood for a differential? -for a CBC?
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Two blood smears and a purple top tube and two blood smears
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What are the main two groups WBCs are divided into?
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Granulocytes and agranulocytes.
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What are the cells that eventually mature into the granulocytes? (neutrophils, eosinophils, and basophils)
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myeloblasts mature into myelocytes, then a band or a stab cell.
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What is a mature granulocyte called?
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PMN or Seg PMN comes from polymorphonuclear and "seg" comes from its segmented nucleus.
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Name the three granulocytes.
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Neutrophils, Eosinophils, and Basophils.
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Describe a Neutrophil.
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They have granules that stain lavender/pink; associated with bacterial infections.
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Describe a Eosinophil.
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They have large granules that stain red; associated with allergic reactions.
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Describe a Basophil.
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They have large granules that stain dark blue; their granules produce heparin to keep the blood from over-clotting.
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Name two agranulocytes.
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Monocytes and Lymphocytes
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Describe a monocyte.
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Originate from monoblasts. they are the largest WBC and can leave the bloodstream to become macrophages, associated with the recovery stage of tissue damage.
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Describe a Lymphocytes.
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Originate from lymphoblast. they are the smallest WBCs and further differentiate into T lymphocytes and B lymphocytes and play an important role in the body's immunity; associated with viral infection's.
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What large cell do platelets or thrombocytes originate from?
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Megakaryocytes (platelets are pieces of the cytoplasm)
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What are the function of platelets?
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They gather around a damaged blood vessel in effort to "plug" the hole, and they release clotting chemicals that cause the formation of a clot that entangles blood cells.
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How is a blood smear made?
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-A drop of blood is placed on one end of a slide. -A "pusher" slide is moved into the drop of blood, allowing it to spread across the edge. -The pusher slide is pushed to the other end of the slide moving in one continuous motion off the edge. - If too much pressure is exerted, the slide will be too thin overall.
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Describe an ideal blood smear.
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-Smooth, not wavy surface -goes from thick to thin. -overall not too thick or too thin. -ends in a feather edge. -covers at least 1/2 the slide in length
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What is the stain used for a blood smear?
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Diff Quick
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Can a medical assistant or lab assistant perform a differential? What do they do?
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NO!! They prepare the slide and bring it into focus on the body of the slide under oil immersion for the hematologist or doctor to read.
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How is a differential performed?
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-scan the body of the slide using a serpentine pattern under oil immersion. -each time a WBC is found it is identified and the corresponding key on the counter is pressed. -when 100 cells have been counted, the bell rings. -The result above each key indicates the percentage of each WBC. -WBC identification and differential.
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List the types of WBCs in order of the highest percentage to the lowest and rarest.
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Segmented, Neutrophils, Banded neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils.
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When scanning a differential slide, what are some abnormal RBCs that might possibly be observed?
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-Macrocyte~large RBC -Microcyte~small RBC -Anisocytosis~abnormal sizes -Target Cell~target shaped -Spherocytes~sphere shaped -Elliptocytes or ovalocytes~oval shaped -Dacryocytes~tear shaped -Poikilocytosis~ abnormal shapes -Abnormal color~ polychromia or hyperchromia, hypochromia -Basophilis stippling~ small RNA dots -Sickle cells~ c-shaped
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When scanning a differential slide how are platelets assessed?
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The hematologist does an approximate count.
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When a blood vessel is damaged, how does the body respond?
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The blood vessel walls contract, platelets become sticky and form a temporary platelet plug, then the clotting facts form a more permanent fibrin clot. The clot shrinks and eventually dissolves when no longer needed.
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How does the fibrin clot form?
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It is the result of a complex chain reaction of 13 clotting factors including two plasma proteins: fibrinogen (factor I) and prothrombin (factor II). Vitamin K is used by the life in the production of prothrombin.
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What are the final steps in the clotting sequence?
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Thromboplastin activates prothrombin to become thrombin, which then activates fibrinogen to become fibrin.
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How does the body stop the coagulation process and why?
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The body produces a natural anticoagulant, heparin, to avoid excessive clotting and the abnormal formation of stationary clots called thromboses, and traveling clots called emboli.
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How do physicians treat patients who are prone to forming internal clots?
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They may be placed on anticoagulant therapy such as heparin, Coumadin, or Warfarin. These patients tend to bleed longer after a venipuncture.
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How often are patients on anticoagulant therapy monitored?
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weekly to determine the amount of time it takes to form a fibrin clot.
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How are hematology tests that are sent to a reference lab drawn? What type of specimen is this?
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In a purple top tube that must be 100% full and Venous blood
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How are CLIA-Waived hematology tests drawn? What type specimen is this?
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Skin puncture blood collected into the device specific for each instrument and Capillary blood.
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Name four CLIA waived hematology tests and their instruments that can be performed in a CoW office?
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Hemoglobin test-hemoCue Hematocrit test- Hematostat Erythrocyte sedimentation rate- SEDIPlast/Westergren Prothrombin Time test- Protime
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Name a moderately complex hematology test and its instrument that is commonly run in some POLs.
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Complete blood count- Quantitative Buffy coat (QBC)
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Which abnormal condition is the hemoglobin test used for?
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Anemia
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Why do hemoglobin reference ranges in men run higher than in women?
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Because women lose blood during menstruation.
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What are the common principles of the hemoglobin test?
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-Collecting blood into the appropriate testing device. -Hemolyzing the blood -Analyzing the released hemoglobin by sending a light source through the specimen -An optical reader receives the light after it passes through the specimen, allowing it to calculate the amount of hemoglobin in the specimen. -The instrument then produces a digital readout expressed in grams per deciliter.
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What is a CLIA-waived instrument commonly used by laboratory assistants in satellite labs in large hospitals that does a hemoglobin test?
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i-STAT Point of Care
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Which abnormal conditions is the hematocrit test used for?
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It tests for anemia in which it is low and Polycythemia in which it is high.
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What is the principle of the microhematocrit test?
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It measures the percentage of packed RBCs that result after centrifuging a specimen and comparing the volume of the packed cells to the total volume of the measured specimen. RBCs occupy almost 50% of the total volume.
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How does the numeric value of the hematocrit test compare to the numeric value of the hemoglobin test?
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The hematocrit value is approximately 3 times the value of the hemoglobin.
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Describe how to perform a microhematocrit test.
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-Collected blood into two heparinized capillary tubes. -Seal one end of each tube. -Centrifuge the specimens. -Determine the percent of RBC volume compared with the total blood volume by a built-in scale. -Results of two tubes should fall within 2% of each other or the test should be repeated. -Hematocrit (Hct)
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The plasma of the spun hematocrit tube should be observed for for which two interfering substances?
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-Hemolysis, where the plasma is red in color -Lipemia, where the plasma appears white and cloudy from a high fat content.
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Make sure you are able to label a spun microhematocrit tube!!!!
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-Air -Plasma -buffy coat -red blood cell layer -Sealant
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What is the principle behind the erythrocyte sedimentation rate (ESR, Sed Rate)?
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-It is the rate at which RBCs settle out of an anticoagulated blood specimen after 60 minutes. -Plasma proteins (especially globulins and fibrinogen) increased during inflammatory conditions cause the RBCs to become sticky and stack together in rouleaux formation (resembling stacked chips) increasing the sed rate.
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Which abnormal condition is the sed rate used for?
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It is a nonspecific screening test to help monitor changes in inflammatory diseases, autoimmune diseases, carcinoma, and leukemia. These conditions cause the sed rate to increase.
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What factors can affect the sed rate test?
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-Size and shape of RBCs -blood not fresh -extreme temperatures -technical factors such as tilting the test tubes, vibrations, and allowing the tubes to sit over 1 hour which increases the sed rate. -air bubbles in the tube lowers the sed rate.
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What is the principle of the prothrombin time (PT) test?
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It measures the amount of time the blood takes to form a fibrin clot. It uses thromboplastin as the active reagent to initiate the coagulation process.
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What abnormal conditions is the PT test used for?
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Most commonly, to monitor patients on anticoagulants such as heparin, Coumadin, or warfarin. Too little blood thinners could cause clots in the blood stream and lead to a stroke or heart attack. -Also, to screen for patients who lack clotting factors, have a liver disease, or are deficient in vitamin K.
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What is the name of the CLIA-waived instrument used for the prothrombin time test?
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Protime
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How should the blood be drawn for the PT test?
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a light blue top tube that is 100% full. It can never be done by skin puncture.
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How are the results of the Pro Time test expressed?
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the results are recorded in seconds and as an international normalized ration
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Reference ranges for normal....
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Hemoglobin-12-18 gm/dL Hematocrit-36-55% ESR-0-20 mm/hr ProTime 16-18 sec or 2-2.5INR
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How should a CBC be drawn?
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a lavender top tube with EDTA filled 100%
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?What level test is a CBC
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Moderately complex
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List seven tests in a CBC.
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-RBC count -WBC count -Pit count -Hct -Hgb -RBC indices -Differential
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Are the reference ranges the same for men and women, adults and children?
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NO! They vary widely
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Are reference ranges the same al over the country?
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NO! they vary in different parts of the country depending on the altitude, average temperature, humidity, etc.That is why CLIA requires that each lab print out their own normal values along with the test results.
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What is the name of the printout of the results of a CBC run on an automated hematology instrument?
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A hemagram
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What is the reference range for the RBC?
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Men: 4.5-6.0 million/cmm Women: 4-5.5million/cmm
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What are the RBC indices and what are they used for?
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-Three mathematic ratios helpful in diagnosing causes of anemia. -MCHC(mean cell Hgb concentration)- used to diagnose anemia and polycythemia. -MCV(mean cell volume)-tells size of the RBCs MCH(mean cell Hgb)-tells concentration of Hgb in RBCs
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What are the formulas for the RBC indices?
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MCHC= Hgb x 100/Hct MCV= Hct x 10/RCB MCH= Hgb x 10/RBC
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What is the reference range for the WBC?
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4,000-11,000/cmm Slightly high-indicates a bacterial infection Extremely high-indicates leukemia Low- indicates a viral infection
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What is the reference range for the platelet count?
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150,000-400,000/cmm
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Folate acid anemia
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caused by a deficiency of folic acid
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Iron-deficiency anemia
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caused by blood loss which caused a deficiency in iron such as menses or ulcers.
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Hereditary Spherocytosis
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sphere-shaped RBCs caused by a genetic abnormality.
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Aplastic anemia
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caused by destruction of stem cells in bone marrow from toxins.
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Perrnicious anemia
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caused by a decrease in vitamin B-12
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Sickle cell anemia
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caused by an inherited abnormal hemoglobin S
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Thalassemia
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Hemolytic anemia caused by inherited abnormal hemoglobin
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Hemolytic Anemia
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caused by destruction of RBCs
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What does a rise in lymphocytes indicate?
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viral infection
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What does an increase in atypical "reactive" lymphocytes indicate?
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Mononucleosis
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acute myelocytic leukemia
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sudden increase in immature granulocytes.
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Chronic myelocytic leukemia
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gradual, long-term increase in immature granulocytes
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Acute lymphocytic leukemia
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sudden increase in immature lymphocytes common in children.
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Chronic Lymphocytic leukemia
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gradual, long-term increase in immature lymphocytes.
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What extra steps does a lab need to take when performing moderately complex tests?
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-Documented training of the operators. -Operator competency testing -Detailed recording of instrument calibration and maintenance. -Two levels of liquid controls -Proficiency testing
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What is the principle behind the QBC Star Centrifugal Hematology System?
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-The QBC system performs a CBC by spinning a capillary sample of blood into its various layers. -A fluorescent dye and a miniature float within the tube can stain and spread out the buffy coat of WBCs and platelets into three additional layers
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What is the principle behind the Coulter Counter system?
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-The coulter Counter performs an automated CBC. -Blood is diluted with an electrolyte solution capable of conducting electricity. -Blood cells pass through an opening in the instrument and cause a pulse or interruption of the electrical circuit. -The pulses are counted, analyzed and calculated by the instrument, which produces a readout.
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Identify these outdated or rarely used hematology devices from their descriptions. -____________-pipette used to dilute blood for manual WBC and RBC. A separate pipette is used for each. -_____________-Collects blood for manual WBC, RBC and platelet count. -_____________-Slide used for manual WBC,RBC, and platelet counts after dilution with a Thoma pipette or Unopette. Blood is placed on the slide and cells are counted.
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-Thoma Pipette -Unopette -Hemocytometer.
