1Component in Partial Thromboplastin Time (PTT) reagent that gives it the name "partial" is
Phospholipid portion of tissue thromboplastin (prepared from brain or plant)
2Substance added to APTT reagent to remove contact activation variability and shorten contact activation time is
Negatively charged activator
3Examples of activators used in APTT reagents include
Silica, kaolin, celite, bentonite, or soluble activator e.g., ellagic acid
4General reference range for APTT is
35 to 45 seconds
5Specimen requirement for APTT testing is
Citrated platelet-poor plasma (prepared by centrifugation for 15 minutes at 2500 x g; platelet count <15,000/µL)
6Two main components of the APTT reagent are
Platelet substitute (phospholipid) and Activator
7Primary diagnostic application of APTT testing includes
Monitoring unfractionated heparin therapy and detecting factor deficiencies in the intrinsic and common pathways
8Reagent incubation temperature and tube specifications used in APTT test procedure are
37°C water bath and 12 x 75-mm glass test tubes
9Volume of patient plasma mixed with APTT reagent and calcium chloride in the test procedure is
0.1 mL PPP + 0.1 mL APTT reagent + 0.1 mL warmed CaCl2
10General reference range for Prothrombin Time (PT) is
10-13 seconds
11Specimen requirement for Prothrombin Time (PT) testing is
Citrated platelet-poor plasma (prepared by centrifugation for 15 minutes at 2500 x g; platelet count <15,000/µL)
12Reagent combination used in the Prothrombin Time (PT) test is
Thromboplastin-Calcium Chloride (CaCl2) reagent (PT reagent, Simplastin)
13Primary diagnostic application of Prothrombin Time (PT) testing includes
Monitoring patients on warfarin/coumarin therapy and detecting factor deficiencies in the extrinsic and common pathways
14Methods of reporting Prothrombin Time (PT) results include
Patient time with control time (seconds), Patient time (seconds) with reference range, Prothrombin ratio, and INR
15Definition of International Normalized Ratio (INR) is
Standardized way of reporting PT that corrects for variability in PT results caused by variable sensitivities of thromboplastin agents
16Target INR range recommended for most clinical indications during Coumadin therapy is
2.0 to 3.0 (or 2.5 to 3.5 for patients with a mechanical heart valve)
17Formula used to calculate International Normalized Ratio (INR) is
(Patient's PT / Mean Normal PT)^ISI
18Meaning of the acronym ISI in coagulation testing is
International Sensitivity Index
19Relationship between ISI value and thromboplastin reagent sensitivity is
More sensitive thromboplastins have ISI < 1.0 (longer PT), while less sensitive reagents have ISI > 1.0 (shorter PT)
20Mechanism of action of Coumarin/Warfarin drugs is
Vitamin K antagonists (VKAs) that interfere with normal synthesis of Factors II, VII, IX, and X as well as Proteins C and S
21Reagents used for reversal of Coumarin/Warfarin overdose include
Vitamin K (oral/intravenous), Fresh-frozen plasma, Prothrombin complex concentrate, and Recombinant activated factor VII (rFVIIa)
22Mechanism of action of Unfractionated Heparin (UFH) is
Accelerating the binding of antithrombin to target enzymes like thrombin and factor Xa
23Monitoring assays routinely required for Unfractionated Heparin (UFH) therapy include
Partial thromboplastin time (PTT) or Activated clotting time (ACT) assay
24Specific agent used to neutralize Unfractionated Heparin (UFH) is
Protamine sulfate (protein extracted from salmon sperm)
25Specific clinical scenarios where Activated Clotting Time (ACT) is useful include
Point-of-care assay at bedside, cardiac catheterization laboratory, or surgical suite for high UFH dosages
26Production process used to obtain Low-Molecular-Weight Heparin (LMWH) is
Controlled fragmentation of heparin
27Primary enzymatic target inhibited by Low-Molecular-Weight Heparin (LMWH) via antithrombin III is
Activated factor X (Factor Xa)
28Route of administration for Low-Molecular-Weight Heparin (LMWH) is
Subcutaneous injection
29Advantages of LMWH compared to unfractionated heparin include
Lowered incidence of heparin-induced thrombocytopenia, lowered incidence of hemorrhage, and lowered incidence of osteoporosis
30Disadvantages of LMWH compared to unfractionated heparin include
Increased cost and more complicated monitoring
31Measurement principle utilized in BBL Fibrometer mechanical clot detection is
Measures a change in conductivity between two metal electrodes in plasma
32Measurement principle utilized in Diagnostica Stago analyzers is
Electromagnetic field detects the oscillation of a steel ball within the plasma-reagent solution
33Detection principle used in photo-optical (turbidimetric) coagulometers is
Detects a change in plasma optical density during clotting
34Detection principle used in nephelometric coagulation testing is
Measures 90-degree or forward-angle light scatter
35Detection principle used in chromogenic (amidolytic) coagulation assays is
Uses a synthetic oligopeptide substrate conjugated to a chromophore (usually para-nitroaniline or pNA)
36Detection principle used in immunologic coagulation assays is
Based on antigen-antibody reactions similar to those used in nephelometry
37Primary purpose of performing Substitution Tests in coagulation is
Identify specific factor deficiency by mixing correction reagents with patient's plasma and repeating PT and/or APTT
38Coagulation factor content in Fresh Plasma (Normal Plasma) includes
All coagulation factors
39Coagulation factor content in Aged Plasma includes
All coagulation factors EXCEPT Factors V and VIII
40Coagulation factor content in Aged Serum includes
All coagulation factors EXCEPT Factors I, V, VIII, XIII, and II
41Coagulation factor content in Adsorbed Plasma includes
All coagulation factors EXCEPT Factors II, VII, IX, and X
42Factor deficiency pattern indicated when Patient's PT is prolonged and APTT is prolonged is
Member of the Common Pathway (Factors X, V, II, I)
43Factor deficiency pattern indicated when Patient's PT is normal and APTT is prolonged is
Member of the Intrinsic Pathway (Factors XII, XI, IX, VIII)
44Factor deficiency pattern indicated when Patient's PT is prolonged and APTT is normal is
Member of the Extrinsic Pathway (Factor VII)
45Specific factor deficiencies detected by Stypven time (Russell's Viper Venom Time) include
Fibrinogen, prothrombin, and factors V and X
46Key operational feature differentiating Stypven time from PT is
Bypasses Factor VII action by directly activating Factor X to Xa
47Normal reference value range for Stypven time is
20 to 25 seconds
48Primary clinical application and reference range of Dilute Russell's Viper Venom Time (dRVVT) are
Detect lupus anticoagulants; Normal Value: 30 to 35 seconds
49Clinical causes that result in prolonged Thrombin Time (TT) include
Low fibrinogen level, impaired fibrinogen function, presence of heparin, fibrin(ogen) degradation products, and streptokinase
50Normal reference value range for Thrombin Time (TT) is
15 to 18 seconds
51Source organism and enzyme function of Reptilase are
Venom of Bothrops atrox snake; converts fibrinogen to fibrin unaffected by heparin
52Normal reference value range for Reptilase Time is
10 to 15 seconds
53Reptilase Time result expected in the presence of Heparin Therapy is
Normal (unlike Thrombin Time which is prolonged)
54Methodological interval requirement for passing needle tip/tilting tube in whole blood clotting tests is
Every 30 seconds
55Normal reference value range for Slide or Drop Method Clotting Time is
2 to 4 minutes
56Water bath temperature and tube count used in Lee and White Whole Blood Clotting Time are
37°C water bath with three test tubes
57Normal reference value range for Lee and White Whole Blood Clotting Time is
7 to 15 minutes
58Effects of Penicillin G (carbenicillin and ticarcillin) on the coagulation system include
Weakens platelet function, platelet aggregation, and interaction of VWF with platelets; increases bleeding time
59Effects of DDAVP (1-desamino-8-D-arginine vasopressin) on the coagulation system include
Increases plasma levels of VIII:C by releasing endogenous protein from body storage sites; can shorten APTT
60Effects of Isoniazid (INH) on the coagulation system include
Can produce thrombocytopenia and increase bleeding time
61Effects of Aspirin products on the coagulation system include
Prolongs bleeding time by inhibiting thromboxane A2 synthesis in platelets
62Effects of Phenothiazines on the coagulation system include
Stimulates production of a "lupus anticoagulant" in circulation; prolongs APTT
63Effects of Phenylbutazone on the coagulation system include
Weakens platelet function, enhances effect of warfarin, and may prolong bleeding time
64Effects of Metronidazole on the coagulation system include
Improves effect of warfarin in a patient on both drugs; can prolong PT
65Effects of Streptomycin on the coagulation system include
Stimulates formation of inhibitors to Factor V; can prolong PT and possibly APTT