Term
| special precautions to take regarding specimen collection and processing for coagulation studies |
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Definition
| Blood should be anticoagulated with sodium citrate in a 9:1 dilution with freshly collected blood. The samples need to be centrifuged as soon as possible after collection for a minimum of 10 minutes at 1000 ref to remove plasma to a plastic tube and keep refrigerated until ready to test. There needs to be plasma in the sample because plasma contains all the clotting factors. |
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Term
| determine specimen appropriateness |
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Definition
| There needs to be plasma in the sample because plasma contains all the clotting factors |
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Term
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Definition
| : in vivo measurement of platelet function, measures the time required for bleeding to cease from a superficial skin cut |
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Term
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Definition
| measures the time needed for plasma to clot after adding calcium and tissue factor. The complex formed between plasma Factor VII and tissue factor, in the presence of calcium, directly activated Factor X. This assay measures the coagulation factor of the extrinsic and common pathways with the exception of Factor XIII. |
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Term
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Definition
| measure the time needed for plasma to form a fibrin clot following the addition of calcium and a phospholipid reagent. A contact activating reagent is included in the phospholipid reagent. The assay measures all of the coagulation factors of the intrinsic and common pathways except for Factor XIII. |
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Term
| Principle of Fibrinogen Assay |
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Definition
| Reference method used to produce a clot based on functional measurement. Additional thrombin in varies dilutions in the presence of fibrinogen forms a clot. The fibrinogen concentration is inversely proportional to the clotting time. |
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Term
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Definition
| Semi-quantitative test used to determine the concentration of fibrin degradation products based on various dilutions of patient’s serum. Fibrin degradation products are indicative of increased fibrinolytic activity |
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Term
| Principle of D-Dimer Assay |
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Definition
| The D-dimer is a specific marker that results from plasmin degradation of fibrin clot, semi-quantitative assay to determine concentration of D-Dimer and rule out venous thromboembolism |
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Term
| Principle of Mixing Studies |
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Definition
| performed to differentiate factor deficiency from presence of circulating inhibitors. The test is a PT and a PTT but with a 50/50 dilution of patient’s plasma mixed with normal plasma. If it is a deficiency, the pooled plasma will fix the abnormal test results. If it is a circulating inhibitor, the pooled plasma will be affected and the results will still be abnormal |
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Term
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Definition
| Constant venous pressure is applied with blood pressure cuff at 40 mmHg; a sterile disposable spring-loaded device is applied to the arm which makes a standard depth and width skin incision on forearm. The time it takes to stop bleeding is measured in minutes |
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Term
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Definition
| In the PT test a thromboplastin (TF and calcium) is added to a citrated patient plasma sample. The time is recorded for fibrin formation |
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Term
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Definition
| : activated partial thromboplastin and calcium are added to the patient plasma sample. The time is recorded for fibrin formation. |
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Term
| Procedure for Fibrinogen Assay |
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Definition
| Thrombin is added to various known dilutions of concentrations of fibrinogen, clotting time in measured |
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Term
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Definition
| Special collection tubes contain thrombin and fibrinolytic inhibitor to prevent in vitro fibrinolysis. Patient’s serum is mixed with latex particles coated with antibodies to FDP, the reaction is observed macroscopically. The test does not distinguish between fibrin degradation products and fibrinogen degradation products. |
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Term
| Procedure for D-Dimer Assay |
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Definition
| monoclonal antibodies against D-dimer fragment are added to the patient sample. The reaction is read macroscopically for latex agglutination. The patient sample is diluted, and latex is added to diluted and undiluted samples. High D-dimer levels are associated with both samples showing agglutination. |
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Term
| The clinical significance of BT test |
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Definition
| : Bleeding time is used as a screening test for vWF. Patients with low platelet counts and specific medical conditions have prolonged bleeding time |
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Term
| The clinical significance of PT test |
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Definition
| This test is used to detect deficiencies in clotting factors in the extrinsic or common pathways or monitor oral anticoagulant therapy. |
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Term
| The clinical significance of APTT |
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Definition
| This test is used to monitor heparin therapy as well as screen for inherited or acquired deficiencies or proteins in the intrinsic or common pathways. |
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Term
| The clinical significance Fibrinogen Assay |
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Definition
| Reference method to quantitative fibrinogen concentration. Decreased fibrinogen indicated DIC, primary/secondary fibrinolysis, liver disease or congenital disorders. Increased fibrinogen indicated inflammatory disorders, pregnancy and women on oral contraceptives. |
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Term
| The clinical significance FDP test |
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Definition
| FDP levels will be abnormal in liver disease alcoholic cirrhosis, kidney disease, cardiac disease postsurgical complications, carcinoma, myocardial infarctions, pulmonary embolism, DVT, eclampsia and DIC. |
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Term
| The clinical significance D-Dimer Assay |
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Definition
| Semi-quantitative assay for D-dimer fragments. Elevated levels are associated with DIC, pulmonary embolism, venous thromboembolism, arterial thromboembolism, recent trauma or surgery, cirrhotic liver disease and renal failure. |
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Term
| The clinical significance of mixing studies |
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Definition
| This test is used when a patients PT or APTT is abnormal. It is used to determine if the abnormal results are due to a factor deficiency or circulating inhibitors. |
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Term
| appropriate laboratory procedure for monitoring heparin therapy and oral anticoagulant therapy. |
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Definition
| The APTT test monitors standard (unfractionated) heparin therapy. Anti- Xa Assay is used to monitor low molecular weight heparin. ACT is used to monitor heparin therapy bedside |
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Term
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Definition
| PT test monitors oral anticoagulant therapy. |
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Term
| Describe the international normalized ratio (INR) |
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Definition
| The INR is the standard for monitoring long term anticoagulant therapy. It is independent of the reagents and methods. It is determined from the PT and reported on patients for monitoring anticoagulant therapy. |
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Term
| 7. Calculate the INR given patient’s prothrombin time (PT); mean normal PT, and international sensitivity index (ISI) |
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Definition
| INR = (patient’s PT/ Mean normal PT) ^ ISI (provided by manufacturer) |
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Term
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Definition
| decreased Factor VII, mildly decreased Factor II, V and X, warfarin given at initiation, Mild DIC, mild vitamin K deficiency or mild liver disease |
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Term
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Definition
| heparin, decreased factor VII, IX or XI, factor inhibitor, Lupus inhibitor, decreased factor XII, prekalikrein, HMW or kininogen |
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Term
| A decreased fibrinogen assay means |
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Definition
| DIC, primary/secondary fibrinolysis, liver disease or congenital disorders |
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Term
| An increased fibrinogen assay means |
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Definition
| inflammatory disorders, pregnancy, women on oral contraceptives |
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Term
| An abnormal FDP test means |
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Definition
| : Liver disease, alcoholic cirrhosis, kidney disease, cardiac disease, postsurgical complications, carcinoma, myocardial infarctions, pulmonary embolism, DVT, eclampsia and DIC. |
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Term
| An elevated D-dimer test means |
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Definition
| DIC, trauma, surgery, hematoma, arterial thrombosis, general hospitalization, pregnancy, cancer, diabetes, thrombolytic therapy, and older age. |
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Term
| Correlate collection and processing procedures of the blood specimen with potential problems in coagulation testing. |
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Definition
| The 1:9 ratio is critical for valid results. If underfilled the overabundance of citrate will bind calcium in the test procedure and produce falsely prolonged test results. If overfilled insufficient calcium bonds can cause clotting to occur in the tube and falsely prolonged results. |
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Term
| Defend the use of 3.2% sodium citrate as an anticoagulant for coagulation studies |
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Definition
| In a normal hematocrit there is a smaller volume of plasma relative to citrate and the excess free citrate binds calcium in the test procedure. If a falsely prolonged clotting time is suspected than the citrate concentration may be off. |
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Term
| Select and defend the most appropriate laboratory tests to monitor anticoagulant therapy, interpret the results, and assess conditions that could affect these tests |
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Definition
| Prothrombin time test monitors oral anticoagulant therapy. A prolonged PT could indicate a presence of the anticoagulant. The results are reported used the INR. Activated partial thromboplastin time is used to monitor heparin therapy, interference in conversion of fibrinogen to fibrin indicated presence of heparin. Heparin is also monitored using the Anti-Xa and the ACT (POC) test. |
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Term
| How does the Fibrinometer detect the time of clot formation for the PT and APTT assays? |
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Definition
| The Fibrinometer detects the time of clot formation by detecting an electrical current through the probe via two electrodes. One electrode moves in and out of the reaction well and the stationary electrode stays inside the reaction well. The small hook on the end of the moving electrode picks up and fibrin strand that has formed and moves back up to the resting position carrying the fibrin strand. The fibrin strand which is still connected to the fibrin clot in the reaction well completes the electrical circuit between the stationary electrode and the moving electrode. The electrical current runs through the probe and triggers the timer to stop. The stopping time is indicative of the time it takes a clot to form. |
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Term
| Briefly describe the reagent reaction in the PT assay (What does reagent contain? What does it do?) |
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Definition
| The PT assay reagent is freeze dried thomboplastin prepared from rabbit cerebral tissue. It contains a specific heparin inhibitor in order to indicate any deficiencies related to prothrombin complex. In the PT assay the reconstituted thomboplastin contains sources of calcium and tissue factor which allows the patients plasma to clot via extrinsic and common pathway (activation of factor X). |
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Term
| Briefly describe the reagent reactions in the APTT assay (What do reagents contain? What do they do?) |
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Definition
| The APTT assay reagents are Actin and Calcium Chloride. The Actin reagent is used as a contact factor activator in that it provides a negative surface which is necessary for the intrinsic pathway to be activated. It contains the phospholipid surfaces to stimulate platelet surfaces with the Actin activator which allows for factor XII activation (beginning of intrinsic pathway). The calcium chloride is necessary for the intrinsic and common pathway to proceed. |
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Term
| What concentration and type of anticoagulant is used for patient samples for PT and APTT assays |
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Definition
| For both the Protime and PTT the patient blood should be anticoagulated with sodium citrate in the ratio of one part anticoagulant to nine parts freshly collected blood. |
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Term
| Why is it necessary not to underfill or overfill the Vacutainer tube during specimen collection for coag testing? |
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Definition
| The Vacutainer tube should not be under or over filled because the dilution of the blood to anticoagulant in the tube is very specific. Over or under dilutions could change the results of the Protime and PTT drastically. An underfilled tube increases the concentration of citrate which can then bind calcium in the test procedure and produce falsely prolonged test results. Overfilling can also produce prolonged results in that there are insufficient calcium bonds which allows for clots to occur in the sample tube. |
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Term
| Because of variations in reagents, methods, and instruments used to determine PT, the WHO recommends PT results be converted to ______________________when using PT as a therapeutic drug monitor for Coumadin |
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Definition
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Term
| Given that the ISI of our thomboplastin reagent is 1.28, and the geometric mean of the Protime reference range is 12, calculate the INR of each of today’s patients showing the formula |
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Definition
INR = (patient’s PT/ Mean normal PT) ISI
INR for Patient 1 = (38.2/12)1.28 = 4.4
INR for Patient 2 = (12.35/12)1.28 = 1.0 |
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Term
If a person has a Factor VII deficiency, you would expect the PT to be _____________ and the
APTT to be _________________ (prolonged vs. normal). |
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Definition
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Term
| 2 corrective actions that could be taken for controls out of reference range |
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Definition
| It is possible that the tech made up the controls incorrectly, to remedy that problem all controls should be remade. It is also possible that the pipettes are calibrated incorrectly; to remedy that one could use a different set of pipettes, and see if the controls fall within range. |
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Term
| Describe the coagulation cascade reactions in the common pathway |
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Definition
| The coagulation cascade reaction in the common pathway can be activated by the intrinsic Xase complex and/or the extrinsic Xase complex. Either of these complexes can activate factor X which can combine with factor V, the phospholipid surface of the platelet and calcium to form the prothrombinase complex. This complex activates Prothrombin to thrombin, which can activate factor XIII to crosslink fibrin and/or thrombin can activate fibrinogen to fibrin which is then cross-linked to form the fibrin plug. |
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Term
| If the patient’s fibrinogen clotting time is more prolonged than the clotting time of Standard 5, what is the appropriate next step? |
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Definition
| If the patient’s fibrinogen clotting time is more prolonged than the clotting time of standard 5 then that is characteristic of a low concentration specimen. The AMR of the procedure is 92-924 mg/dL. If the patients specimen falls outside of this AMR range then the next step should be to pre-dilute the sample 1:5 instead of 1:10. The measured concentration would be divided by 2 to obtain a reportable result. |
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Term
| Name 2 transfusion blood products that can be used to treat a low fibrinogen level |
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Definition
| 2 transfusion blood products that can be used to treat a low fibrinogen level are (1) cryoprecipitate or (2) fresh frozen plasma (FFP). |
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Term
| If a patient’s FDP level is elevated, but the D-dimer is not, what is the most likely condition? Identify 3 diseases where this could occur. |
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Definition
| The most likely condition is hyper primary fibrinolysis (fibrinogenolysis) with hypo secondary fibrinolysis. Three diseases where this could occur are (1) metastatic prostatic carcinoma (2) hemorrhagic states following cardiac bypass surgery and (3) hepatic diseases. |
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Term
| D-dimer has a “negative predictive value” for DVT and VTE. What does negative predictive value mean in this case? |
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Definition
| A negative predictive value for DVT and VTE means that the negative D-dimer test correlates very strongly with the absence of these conditions |
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Term
| If the Protime and PTT are prolonged, the Fibrinogen is decreased, and the D-Dimer is elevated what syndrome is the most likely cause? |
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Definition
| The mostly likely cause of these test results are DIC (disseminated intravascular coagulation). |
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Term
| How do you make a 1:10 dilution |
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Definition
| 100 uL of patient sample, 900 uL of buffered solution |
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Term
| How do you make a 1: 5 dilution |
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Definition
| 100 uL of sample, 400 uL of buffered solution, divide the answer by 2 |
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Term
| What do you do when you have to pre-dilute to a 1:20 instead of 1:10 |
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Definition
| multiply measured concentration by 2 |
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Term
| when do you need to make a 1:5 dilution? |
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Definition
| when the result is too high (prolonged) |
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Term
| when do you need to make a 1:20 dilution? |
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Definition
| when the result is too low (too short) |
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Term
| how do you get to a 1:4 from a 1:2 dilution? |
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Definition
| a 1:2 is 100 uL sample, 100 uL diluent, you take 100 uL of the 1:2 and add it to 100uL of diluent |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| Describe an infectious mononucleosis PBS |
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Definition
| low segs, high bands, very high atypical lymphs, and high monos. normal lymphocytes |
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Term
| describe a sickle cell PBS |
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Definition
| normal WBCs count but a lot of nRBCs and increased platelets. sickle cells with target cells, h-j bodies and macrocytes |
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Term
| describe a hereditary sphereocytosis PBS |
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Definition
| high band count with some atypical lymphs, high RDW, sphereocytes |
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Term
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Definition
| high band count and atypical lymphs, slightly increases mono count, low platelets, parasites with echinocytes |
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Term
| Describe an infectious PBS |
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Definition
| some atypical lymphs, eosinophils, polychromasia (retics), microcytes, schitocytes, platelet clumping |
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