Clinical Hemostasis questions
A newly admitted patient has the following coagulation results: PT: 12.9 seconds (N = 12-14 seconds) aPTT: 84 seconds (N = 25-35 seconds) Platelet Count: 200 x 109/L (N = 150-450 x 109/L) A mixing study was performed due to the abnormal aPTT test results. The mixing study demonstrated the following:aPTT was corrected by normal plasma, factor IX deficient plasma, but not by factor VIII deficient plasma. What factor assay should be performed next?
Factor VIII assay
All of the following factors are involved in the initial contact phase of the intrinsic pathway, EXCEPT:
Factor X
The following factors are measured by either the PT or aPTT, EXCEPT:
Factor XIII
Thromboelastography (TEG) is a methodology used to assess blood coagulation. The prothrombin time (PT) and activated partial thromboplastin time (APTT) are more commonly used. All of the following are things that TEG can assess that the PT and APTT cannot assess EXCEPT?
Factor deficiencies
Plasmin is known to degrade Factors Va, VIIIa, and GPIb. What other substance is it known to digest?
Fibrin
Which of the following will impact platelet aggregation when it becomes deficient?
Fibrinogen
Dysfibrinogenemia can be caused by many different structural mutations of the fibrinogen genes, and can result in bleeding, thrombosis, or in some patients, no symptoms. A lab test which differentiates dysfibrinogenemia from afibrinogenemia is:
Fibrinogen antigen assay
The D-dimer is useful in detecting activity in which aspect of hemostasis?
Fibrinolysis
Which one of the following is a true statement about Lupus Anticoagulant (LA)?
LA is an immunoglobulin.
Which of the following tests could be used to determine whether an abnormal screening coagulation test result (PT or aPTT) is caused by a factor deficiency or an inhibitor?
Mixing studies
Which of the following is a quantitative test which is commonly available to determine Protein C and Protein S antigen levels?
Enzyme immunoassay
A deficiency in Plasminogen Activator Inhibitor-1 (PAI-1) can lead to a serious bleeding disorder due to which of the following?
Excessive and unregulated fibrinolysis
Which of the following coagulation pathways includes Factor VII?
Extrinsic
An increased D-Dimer can be associated with all of the following EXCEPT:
Factor Deficiency
Which of the following assays is commonly used to confirm the diagnosis of Activated Protein C resistance?
Factor V Leiden Mutation Assay
The most specific test to detect both presence of Factor V Leiden, also known as activated protein C resistance (APC) and predict risk of thrombosis is:
Factor V Mutation Assay
A specimen drawn from an indwelling catheter that was contaminated by heparin would be indicated by:
Prolonged aPTT and normal reptilase time test
Which of the following is responsible for inhibiting the tissue plasminogen activator?
Protein C
The vascular system contributes to hemostasis in all of the following ways EXCEPT:
Providing smooth endothelial surface
Secondary hypercoagulable states can be caused by all of the following conditions EXCEPT:
Rapid weight loss
Patients who undergo urologic procedures, as well as those with genitourinary tract diseases such as prostate cancer can sometimes be prone to diffuse hemorrhage. A possible cause of this could be which of the following?
Release of urokinases
Ristocetin is used in certain von Willebrand Factor (vWF) functional assays. The reason it is used is because:
Ristocetin enhances binding of vWF to platelet GPIba.
A laboratory professional is going to perform a mixing study to differentiate between a factor deficiency and a coagulation inhibitor as the cause of a prolonged prothrombin time (PT) or activated partial thromboplastin time (aPTT) test result. The mixing study should be performed within what time frame following collection of the specimen?
4 hours
What is the CORRECT blood-to-anticoagulant ratio in blue top (sodium citrate) tubes used for coagulation tests?
9:1
The following describes a clot-based test to assess Protein C function, as well as the results of someone's test who has a protein C deficiency.
A parital thromboplastin time (PTT) is performed using C-depleted normal plasma, a venom activator of protein C (such as Protac), and a heparin neutralizer. The clotting time would not be prolonged in someone with a protein C deficiency.
What are the expected lab results in the condition known as "Afibrinogenemia"?
Elevated PT, elevated aPTT, elevated thrombin time (TT) and elevated reptilase time
A test used to evaluate the abnormalities in the intrinsic coagulation pathway and to monitor heparin therapy is called:
Activated partial thrombloplastin time (aPTT or PTT)
All of the following are coagulation assays that employ low-reagent phospholipids and thus are sensitive to Lupus Anticoagulant (LA) (Antiphospholipid Antibodies) EXCEPT:
Activated partial thromboplastin time (aPTT)
All of the following tests are useful in the diagnosis of heparin induced thrombocytopenia (HIT) EXCEPT:
Dilute partial thromboplastin time (DTT)
In patients who have developed heparin-induced thrombocytopenia with thrombosis (HIT), which of the following should be used to prevent ischemic stroke?
Direct thrombin inhibitors
When monitoring the use of low-molecular-weight heparins becomes necessary, which of the following laboratory tests is recommended?
Anti-Xa
A laboratory test to determine heparin levels in a patient's plasma is:
Anti-factor Xa assay (anti-FXa)
Platelets are:
Fragments of megakaryocyte cytoplasm and do not contain nuclei
The laboratorian completed the mixing study ordered for John Doe. The results are as follows: Initial aPTT result: 167 seconds Initial 1:1 Mix with Normal Pooled Plasma: 158 seconds Incubated 1:1 Mix with Normal Pooled Plasma: 150 seconds Which of the choices below would most likely explain the results for this patient?
Immediate-acting coagulation inhibitor
The process by which the body stops the bleeding after an injury is called:
Hemostasis
Platelet aggregation is blocked upon use of which of the following medications?
Heparin
Which of the following blood collection tubes is appropriate for coagulation testing?
Light blue top tube
A variety of additives are used in blood collection tubes. Which of the following additives prevents clotting by inhibiting thrombin and thromboplastin?
Lithium or sodium heparin
What would be a PROBABLE diagnosis for a habitual alcoholic with slight elevations in the PT and aPTT tests?
Liver disease
Abnormal thrombin times (TT) can be caused by all of the following EXCEPT:
Low platelet count
Anticoagulant drugs which are direct thrombin inhibitors (such as argatroban and bivalirudin) can prolong which of the following clot based assay/s?
PT, aPTT and Ecarin clotting time
After several incidences of deep vein thrombosis (DVT), a patient is to be assessed for hypercoagulability. The following would be an appropriate panel for hypercoagulability screening:
PT, aPTT. Lupus Anticoagulamt (LA) screening, Activated Protein C resistance (APC) , d-dimer screening
A 3-year-old child was brought into the hospital with complaints of recurring conjunctivitis along with "woody" growths on the mucous membranes. Which of the following deficiencies would occur given these symptoms?
Plasminogen
All of the following substances can be used to induce platelet aggregation when performing platelet aggregation studies EXCEPT:
Plasminogen
The thrombomodulin-thrombin complex is known to aid in the activation of which of the following?
Plasminogen
A point-of-care test used to evaluate bleeding problems and monitor antiplatelet medication is called?
Platelet function assay (PFA)
Von Willebrand Factor (vWF) multimer analyses of patient's plasma can be performed by:
SDS agarose gel electrophoresis
What is the anticoagulant most commonly used for routine coagulation testing?
Sodium citrate
A prothrombin time (PT) specimen was collected at an outpatient clinic and will not be picked up by the testing laboratory's courier until several hours later. How should the specimen be stored until it is picked up by the courier?
The tube should remain unopened and be kept at room temperature (20°-25° C).
Thromboelastography is a point of care test which measures which of the following?
The entire coagulation status of the patient
The clot-based assay that is most specific for measuring fibrinogen function is the:
Thrombin time (TT)
Obstruction of a blood vessel caused by a stationary blood clot is called:
Thrombosis
A substance secreted by the vascular endothelial cells that can help to initiate fibrinolysis is:
Tissue plasminogen activator (t-PA)
To obtain accurate aPTT times in patients who have hemophilia and have blood drawn from implanted venous access devices, it is important to:
Treat patient plasma with heparin neutralizers and then do the aPTT
The principle of most commercially available d-dimer assays is:
Using specific antisera to detect d-dimers' neo-epitopes
