BOC Questions for Coagulation
326) Plasma from a patient with lupus coagulation inhibitor can show: a) a prolonged APTT and normal PT b) a prolonged thrombin time c) no change with platelet neutralization d) complete correction when incubated with normal plasma
a) a prolonged APTT and normal PT Patients suspected of a lupus anticoagulant present with a prolonged APTT. Lab assays to detect lupus anticoagulants are the APTT, dilute Russel viper venom test, and Kaolin clotting time. In the presence of LA, the mixing study doesn't correct.
310) Prothrombin is: a) a protein formed by the liver in the presence of Vitamin K b) an enzyme that converts fibrinogen into fibrin threads c) the end product of the reaction between fibrinogen and thrombin d) a protein released by platelets during coagulation
a) a protein formed by the liver in the presence of Vitamin K Prothrombin is produced by the liver cells dependent on Vitamin K as a coenzyme for its functionality. It is released into the blood as a zymogen as a precursor for its active form thrombin.
350) A bedside test that can be used to monitor heparin activity is the: a) activated clotting time b) stypven time c) reptilase time d) partial thromboplastin time
a) activated clotting time The ACT monitors high-dose heparin therapy at clinics, bedside, cardiac catheterization or at a surgical site. The Stypven time is a test using snake venom for testing for lupus. The reptilase time is used to distinguish between heparin contamination and a decreased fibrinogen level.
353) Low molecular weight heparin is monitored by a: a) anti-Xa assay b) APTT c) PT d) anti-IIa assay
a) anti-Xa assay The chromogenic anti-Xa assay is the only assay available to monitor LMWH; it may also be used to measure UFH. The APTT can not be used to monitor low molecular-weight heparin therapy.
297) Which of the following detects or measures platelet function? a) bleeding time b) prothrombin time c) thrombin time d) partial thromboplastin time
a) bleeding time BT assesses platelet function; PT, TT & APTT do not assess platelet function.
298) Platelet aggregation is dependent in vitro on the presence of: a) calcium ions b) sodium citrate c) thrombin d) potassium
a) calcium ions Calcium is required for platelet aggregation.
348) D-dimers are produced from: a) cross-linked and stabilized fibrin clots b) decreased fibrinogen and platelets c) plasminogen converting to plasmin d) generation of thrombin from endothelial cells
a) cross-linked and stabilized fibrin clots D-dimers are produced from cross-linked and stabilized fibrin clots. These clots are dissolved by plasma and D-dimers are released. Therefore, D-dimers suggest a breakdown of fibrin clots, and indicate that clots have been formed at the site of injury.
320) A hemophiliac male and a normal female can produce a: a) female carrier b) male carrier c) male hemophiliac d) normal female
a) female carrier All daughters of hemophiliac men are carriers of the disease; all sons are normal. The gene for Factor VIII lies on the X chromosome.
283) Which of the following is characteristic of Bernard-Soulier syndrome? a) giant platelets b) normal bleeding times c) abnormal aggregation with ADP d) increased platelet count
a) giant platelets Giant platelets, abnormal bleeding time, normal aggregation with ADP, decreased platelet count are characteristic of Bernard-Soulier.
332) Acute disseminated intravascular coagulation is characterized by: a) hypofibrinogenemia b) thrombocytosis c) negative D-dimer d) shortened thrombin time
a) hypofibrinogenemia The lab profile for a patient with acute DIC is: increased PT, APTT and D-dimers, with decreased fibrinogen and platelets.
312) The most potent plasminogen activator in the contact phase of coagulation is: a) kallikrein b) streptokinase c) HMWK d) fibrinogen
a) kallikrein A clot is degraded by plasmin in the fibrinolytic system. Plasminogen is the zymogen producted when Factor XIIa and kallikrein are produced by contact activation.
314) Which of the following is a characteristic of Factor XII deficiency? a) negative bleeding history b) normal clotting times c) decreased risk of thrombosis d) epistaxis
a) negative bleeding history See explanation in question 313 *same*
294) A bleeding time is used to evaluate the activity of: a) platelets b) prothrombin c) labile factor d) Factor XIII
a) platelets Bleeding time (BT) assesses platelet activity.
340) A patient is taking 10 mg per day of Coumadin (warfarin). The results of which of the following lab tests will be most impacted? a) protein C level b) antithrombin III level c) Factor V Leiden mutation d) Factor VIII level
a) protein C level Protein C is a Vitamin K dependent protein; hence warfarin therapy will lower levels of this protein.
266) Normal platelets have a circulating life-span of approximately: a) 5 days b) 10 days c) 20 days d) 30 days
b) 10 days Average life span of platelets in peripheral blood is 9.5 days.
316) Which one of the following factors typically shows an increase in liver disease? a) Factor VII b) Factor VIII c) Factor IX d) Factor X
b) Factor VIII Liver disease affects all Vitamin K dependent factors ( II, VII, IX and X) which will be decreased. Factor VIII is an acute phase reactant that may be elevated in liver disease.
313) Which of the following factor deficiencies is associated with either no bleeding or only a minor bleeding tendency, even after a trauma or surgery? a) Factor X b) Factor XII c) Factor XIII d) Factor V
b) Factor XII Patients with deficiency of Factor XII tend to have thrombotic complications. They do not have bleeding problems most likely due to the lack of activation of fibrin lysis, also due to pathway activation of IX by VIIa/TF complex as well as the activation of Factor XI by thrombin.
325) Patient presents with bleeding 48 hours post tooth extraction. Results are as follows: PT 11.5 sec (ref. range: 10-13 sec) APTT 32.5 sec (ref. range: 23-35 sec) fibrinogen 345 mg/dL (ref. range: 200-400 mg/dL) platelets 324 (ref. range: 150-450) Possible causes are a deficiency in: a) plasminogen b) Factor XIII c) alpha2 anti-plasmin d) Factor XII
b) Factor XIII Factor XIII activity is <5% in congenital or acquired disorders. In adults, bleeding is slow and delayed. The PT, APTT, fibrinogen and platelets will be normal.
311) Which of the following coagulation factors is considered labile? a) II b) V c) VII d) X
b) V Factor V is called labile factor, because its activity diminishes quickly at room temperature. Factor II: prothrombin, VII: stable factors, X: Stuart-Prower.
269) Platelet activity is affected by: a) calcium b) aspirin c) hyperglycemia d) hypoglycemia
b) aspirin Aspirin interferes with prostaglandin metabolism in the platelet.
351) Which of the following lab findings is associated with Factor XIII deficiency? a) prolonged activated partial thromboplastin time b) clot solubility in a 5 molar urea solution c) prolonged thrombin time d) prolonged prothrombin time
b) clot solubility in a 5 molar urea solution Fibrin stabilizing factor is needed to polymerize a clot. Primary screening tests are normal in Factor XIII deficiency. A screening test is based on the solubility of a fibrin clot in 5M urea.
339) Aliquots of plasma with a prolonged PT and APTT are mixed using various ratios of patient plasma and normal plasma. All samples are incubated at 37°C and tested at 10, 30, and 60-min intervals. The PT and APTT results on all of the mixtures are corrected. These results would indicate the presence of: a) circulating anticoagulant b) factor deficiency c) contaminated reagent d) antibodies
b) factor deficiency A mixing study, when corrected, indicates a factor deficiency. Lack of correction indicates an inhibitor. Some inhibitors may only become evident after the patient's plasma is allowed to interact with normal plasma after incubation. In this case, correction occurred immediately, as well as after incubation, confirming a factor deficiency.
295) A patient has been taking aspirin regularly for arthritic pain. Which one of the following tests is most likely to be abnormal in this patient? a) platelet count b) template bleeding time c) prothrombin time d) activated partial thromboplastin time
b) template bleeding time BT assesses platelet number and function; platelet count only assesses platelet number; PT & APTT do not assess platelet number or function.
345) In a Clauss fibrinogen method, the time to clot formation in plasma is measured after the addition of: a) calcium b) thrombin c) phospholipids d) kaolin
b) thrombin In a Clauss fibrinogen, a standard amount of thrombin is added to diluted plasma, and the time required for clot formation is recorded.
344) The best test to determine if a sample is contaminated with heparin is: a) fibrinogen b) thrombin time c) prothrombin time d) stypven time
b) thrombin time A prolonged thrombin time may be considered evident of diminished or abnormal fibrinogen; however, the presence of AT activity such as heparin, must be ruled out.
334) Patient results are as follows: PT 17.5 sec (ref. range: 10-13 sec) APTT 56.7 sec (ref. range: 23-35 sec) D-dimer 698 ng/mL (<250 ng/mL)( fibrinogen 123 mg/dL (200 - 400 mg/dL) platelet count 102 (150 - 450) This workup suggests: a) blood clot b) hemorrhage c) DIC d) HUS
c) DIC The lab profile for a DIC workup includes increased PT, APTT and D-dimers, with decreased fibrinogen and platelets.
317) A patient has a normal prothrombin time and a prolonged activated partial thromboplastin time using a kaolin activator. The APTT corrects to normal when the incubation time is increased. These results suggest that the patient has: a) hemophilia A (Factor VIII deficiency) b) Hageman Factor (XII) deficiency c) Fletcher Factor deficiency (prekalikrein) d) Factor V deficiency
c) Fletcher Factor deficiency (prekalikrein) A prolonged APTT with a normal PT denotes a problem with the intrinsic pathway, so Factors VIII, IX, XI would be looked at, these deficiencies would correct in a mixing study. A characteristic of prekalikrein deficiency is the correction of the PTT when incubated for 10 minutes with kaolin, Celite, silica or ellagic acid.
305) Coagulation factors affected by warfarin (Coumadin) drugs are: a) VIII, IX and X b) I, II, V and VII c) II, VII, IX and X d) II, V and VII
c) II, VII, IX and X Warfarin interferes with the carboxylation of vitamin K factors by interrupting the enzymatic phase of the reaction. Factors are inhibited according to their half life, VII having the shortest (4-5 hours) and II the longest (2-3 days).
308) Which of the following factors is used only in the extrinsic coagulation pathway? a) II b) V c) VII d) VIII
c) VII The extrinsic pathway is initiated by the release of tissue thromboplastin that has been expressed after damage to a vessel. Factor VII forms a complex with tissue thromboplastin and calcium. Factors II and VII are found in the common pathway, and Factor VIII is in the intrinsic pathway.
296) A platelet count done by phase microscopy is 200. A standardized template bleeding time on the same person is 15 min. (ref. range 4.5 + 1.5 min). This indicates that: a) the Duke method should have been used for the bleeding time b) the manual platelet count is in error c) abnormal platelet function should be suspected d) the results are expected
c) abnormal platelet function should be suspected
347) Excess D-dimer indicate that clots have been: a) converted to fibrin monomers b) released into circulation c) formed and are being excessively lysed d) stimulated to activate platelets
c) formed and are being excessively lysed D-dimers are produced from crosslinked and stabilized fibrin clots. These clots are dissolved by plasma and D-dimers suggest a breakdown of fibrin clots, and indicate that clots have been formed at the site of injury.
306) Which of the following statements concerning Vitamin K is NOT true? a) there are 2 sources of Vitamin K; vegetable & bacterial b) Vitamin K converts precursor molecules into functional coagulation factors c) heparin inhibits the action of Vitamin K d) Vitamin K is fat soluble.
c) heparin inhibits the action of Vitamin K Vitamin K is present in green vegetables, fish, liver & tobacco and synthesized by bacteria in the intestine. Naturally occurring vitamin K is fat soluble. Warfarin is the most popular vitamin K antagonist. Heparin inhibits Factor Xa and thrombin.
282) Which of the following is characteristic of platelet disorders? a) deep muscle hemorrhages b) retroperitoneal hemorrhages c) mucous membrane hemorrhages d) severely prolonged clotting times
c) mucous membrane hemorrhages MM hemorrhage is typical of platelet disorders; remaining choices are typical of coagulation factor disorders.
337) In the APTT test, the patient's plasma is mixed with: a) ADP and calcium b) tissue thromboplastin and collagen c) phospholipid and calcium d) tissue thromboplastin and calcium
c) phospholipid and calcium The APTT reagent contains phospholipid and a negatively-charged particulate activator such as kaolin, ellagic acid, or Celite. Ionic calcium and phospholipid are supplied as reagents.
336) The prothrombin time test requires that the patient's citrated plasma be combined with: a) platelet lipids b) thromboplastin c) Ca++ and platelet lipids d) Ca++ and thromboplastin
d) Ca++ and thromboplastin PT thromboplastin reagents are prepared from recombinant or affinity purified tissue factor suspended in phospholipid mixed with a buffered 0.025M solution of calcium chloride.
307) Which of the following is Vitamin-K dependent? a) Factor XII b) fibrinogen c) antithrombin III d) Factor VII
d) Factor VII Factor VII (proconvertin) is a single-chain glycoprotein that is Vitamin K dependent and remains stable for 4-5 hours in blood. Produced in the liver, it has the shortest half-life; therefore, it is the first factor affected when a Vitamin K antagonist such as Warfarin is administered.
315) The 2 factors that differentiate liver disease from Vitamin K deficiency are: a) II and VII b) IX and VII c) VIII and IX d) V and VII
d) V and VII Factors V and VII are helpful in distinguishing between liver disease and Vitamin K deficiency. Factor VII is a Vitamin K dependent factor; however, Factor V is not and will not be decreased. Both factors will be decreased in liver disease.
319) A 4-yr-old boy presents with chronic ear infections and is on prophylactic antibiotics. He presents with bleeding. Factor assays reveal: Factor VIII 100% (ref. range: 50 - 150%) Factor V 75% (ref. range: 50 - 150%) Factor IX 38% (ref. range: 50 - 150%) Factor II 22% (ref. range: 50 - 150%) Possible causes are: a) Factor II deficiency b) lupus anticoagulant c) hemophilia d) Vitamin K deficiency
d) Vitamin K deficiency Long-term antibiotic therapy disrupts normal flora, which provides a source of Vitamin K synthesis. This results in a Vitamin K deficiency.
352) Heparin acts by: a) precipitating fibrinogen b) binding calcium c) activating plasmin d) inhibiting thrombin
d) inhibiting thrombin Heparin acts by inhibiting thrombin and Factor Xa. Anticoagulants, such as sodium citrate, act by binding calcium to prevent a blood sample from clotting.
338) The APTT: a) tests the extrinsic coagulation pathway b) monitors Coumadin therapy c) requires tissue thromboplastin d) monitors heparin therapy
d) monitors heparin therapy The APTT is performed to monitor the effects of unfractionated heparin, to detect factor deficiencies, and the presence of inhibitors. The PT tests the extrinsic pathway and requires thromboplastin. It is also used to monitor warfarin (Coumadin) therapy.
291) The automated platelet count on an EDTA specimen is 58. The platelet estimate on the blood smear appears normal, but it was noted that the platelets were surrounding the neutrophils. The next step should be to: a) report the automated platelet count since it is more accurate than a platelet estimate. b) warm the EDTA tube and repeat the automated platelet count c) rerun the original specimen since the platelet count and blood smear estimate do not match d) recollect a specimen using a different anticoagulant
d) recollect a specimen using a different anticoagulant Platelet satellitism is reduced by collecting sample in sodium citrate.
290) An automated platelet count indicates platelet clumping, which is confirmed by examining the smear. The technician should: a) repeat the count on the same sample b) report the automated count c) perform a manual count d) recollect in sodium citrate
d) recollect in sodium citrate Platelet clumping is reduced by collecting sample in sodium citrate.
342) A prolonged thrombin time and normal reptilase-R time are characteristic of: a) dysfibrinogenemia b) increased D-dimer c) fibrin monomer-split product complexes d) therapeutic heparinization
d) therapeutic herparinization A prolonged thrombin time can indicate diminished or abnormal fibrinogen, the presence of FDPs, paraproteins, and heparin. Reptilase is insensitive to the effects of herparin, and sensitive to dysfibrinogenemia. Therefore, when the TT is prolonged and the reptilase test is normal, this confirms the presence of heparin.
309) Hageman Factor (XII) is involved in each of the following reactions EXCEPT: a) activation of C1 to C1 esterase b) activation of plasminogen c) activation of Factor XI d) transformation of fibrinogen to fibrin
d) transformation of fibrinogen to fibrin Factor XII is a contact factor, which is activated to Factor XIIa. It is responsible for the activation of Factor XI to Factor XIa. Fibrinogen is converted to fibrin by the action of thrombin.
318) The results on a patient are: PT 18.5 sec (ref. range: 11.0-13.5) APTT 47.5 sec (ref. range: 24-35) thrombin time 14.0 sec (ref. range: 12-19) ATIII 82% (70-130%) protein C 54% (77-167%) protein S 48% (65-140%) activated protein C resistance 2.6 (>2.1) These results reflect: a) thrombophila b) Factor IX deficiency c) heparin d) warfarin
d) warfarin Warfarin is a Vitamin K antagonist; coagulation Factors II, VII, IX, X, Protein C, and S are reduced as nonfunctional molecules are produced. The rate of reduction is based on the half-life of the factors.