Coagulation Factors Substitution Test

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Questions and Answers

What is the primary purpose of the Bethesda unit in coagulation testing?

To detect weak inhibitors in plasma samples

To differentiate between hemophilia A and von Willebrand disease

To measure the activity of FVIII inhibitors (correct)

To correlate inhibitor units with predicted bleeding risk

What is the recommended approach for detecting weak inhibitors using the Bethesda unit?

Prolonging the incubation period at lower temperatures or room temperature (correct)

Increasing the sample volume to be tested

Diluting the sample to be tested

Prolonging the incubation period at higher temperatures

What is the relationship between the inhibitor unit and predicted bleeding risk?

The inhibitor unit is only useful for differentiating between hemophilia A and von Willebrand disease

The inhibitor unit does not necessarily correlate with predicted bleeding risk (correct)

The inhibitor unit is not a reliable measure of bleeding risk

The inhibitor unit directly correlates with predicted bleeding risk

What is the recommended course of action if a plasma sample contains more than one unit of inhibitor per ml?

Repeat the test until the percent residual factor is close to 50% Signup and view all the answers

What is the purpose of the Platelet Neutralization Procedure (PNP) in coagulation testing?

To detect the presence of lupus anticoagulant Signup and view all the answers

How does the Platelet Neutralization Procedure (PNP) work to detect lupus anticoagulant?

By increasing the quantity of phospholipid in the test system, reducing the impact of the phospholipid-dependent anticoagulant Signup and view all the answers

What is the expected result of the Platelet Neutralization Procedure (PNP) in the presence of lupus anticoagulant?

A shortened APTT of 3-5 seconds or more Signup and view all the answers

What is the purpose of combining the patient's weak plasma with the suspension of ruptured platelets in the Platelet Neutralization Procedure (PNP)?

To provide a source of phospholipid for the test Signup and view all the answers

What is the purpose of comparing the clotting time of the patient's sample with a similar mixture where the platelets are replaced with calcium chloride in the Platelet Neutralization Procedure (PNP)?

To detect the presence of lupus anticoagulant Signup and view all the answers

Which of the following is a characteristic laboratory finding in Disseminated Intravascular Coagulation (DIC)?

Increased fibrin degradation products Signup and view all the answers

What is the primary purpose of the Protamine Sulfate Dilution Test in coagulation analysis?

To detect the presence of fibrin monomers or fibrin degradation products Signup and view all the answers

Which of the following is a common indication for DDAVP (desmopressin) therapy in coagulation disorders?

Recurrent venous thrombosis Signup and view all the answers

How does liver disease affect coagulation test results during the anhepatic phase of liver transplantation?

Results in prolonged prothrombin time and activated partial thromboplastin time Signup and view all the answers

What is the relationship between obesity and the risk of recurrent venous thrombosis?

Obesity is associated with an increased risk of recurrent venous thrombosis, but the significance is unclear Signup and view all the answers

What is the primary cause of prolonged clotting times in Disseminated Intravascular Coagulation (DIC)?

Depletion of coagulation factors Signup and view all the answers

What is the mechanism of action of DDAVP (desmopressin) in the treatment of von Willebrand disease?

Stimulates the release of von Willebrand factor from endothelial cells Signup and view all the answers

Which of the following tests is used to determine the presence of lysis products in a sample?

Both A and B Signup and view all the answers

What is the purpose of the Protamine Sulfate Dilution Test in coagulation studies?

To detect heparin contamination in a sample Signup and view all the answers

In the context of coagulation disorders, what is a common cause of prolonged prothrombin time (PT) and activated partial thromboplastin time (aPTT)?

Liver disease Signup and view all the answers

What is the recommended course of action if vitamin K administration does not correct a prolonged prothrombin time (PT)?

Perform additional tests to assess for liver disease Signup and view all the answers

Which of the following tests is most specific for detecting intravascular fibrin formation?

Ethanol Gelation Test Signup and view all the answers

In which condition would you expect to find a high level of D-dimers?

Disseminated Intravascular Coagulation (DIC) Signup and view all the answers

What is the principle behind the Protamine Sulfate Dilution Test?

Protamine sulfate neutralizes heparin, allowing the detection of heparin-like inhibitors Signup and view all the answers

Which of the following conditions is associated with a decreased level of plasminogen?

Liver disease (cirrhosis) Signup and view all the answers

What is the purpose of the DDAVP (desmopressin) therapy?

To increase fibrinogen levels Signup and view all the answers

Which test is considered less sensitive but more specific than the Protamine Sulfate Dilution Test for detecting heparin-like inhibitors?

Ethanol Gelation Test Signup and view all the answers

Study Notes

Coagulation Tests and Interpretation

APTT (Activated Partial Thromboplastin Time) can indicate deficiencies in coagulation factors.
Correction of APTT with aged serum suggests factors 7, 9, 10, 11, or 12 may be missing.
APTT not corrected with adsorbed plasma indicates factors 2, 7, 9, or 10 are absent.

Patient A Analysis

APTT: prolonged; PT (Prothrombin Time): normal.
Adsorbed plasma: APTT not corrected; aged serum: APTT corrected.
Factor 9 deficiency confirmed after canceling extrinsic and irrelevant factors.

Patient B Analysis

Similar initial lab results as Patient A: prolonged APTT, normal PT.
Adsorbed plasma: APTT corrected; aged serum: APTT not corrected.
Indicates deficiency in intrinsic pathway factors, specifically factor 8.

Factor Presence in Plasma Types

Adsorbed plasma rich in factors 1, 5, 8, 11, and 12.
Aged serum deficient in factors 1, 2, 5, 8, and 13.
Factor cancellation leads to the identification of affected factors.

Thrombin Time Assessment

Thrombin Time (TT) prolonged due to low fibrinogen levels affects thrombin's ability to cleave fibrinogen.
Factors 1 and 5 considered for deficiency based on residual activity from thrombin response.

Patient F Analysis

Cases of low or absent fibrinogen: Fibrinogenemia, Dysfibrinogenemia, Hypofibrinogenemia.
Thrombin time is crucial for diagnosing fibrinogen deficiency.

Patient E Analysis

APTT normal; PT prolonged indicates a problem with the extrinsic pathway.
Adsorbed plasma: PT not corrected; aged serum: PT corrected confirming factor 7 deficiency.

Inhibitor Studies for Factor VIII

Factor VIII measured post-incubation to assess residual activity against inhibitors.
Bethesda units quantify inhibitor levels based on dilution needed for neutralization of factor VIII.
Low responders identified with ≤ 5 Bethesda units, indicating treatment requirement with rapid factor VIII doses.

Residual Factor Activity Calculation

Formula: % Residual Factor Activity = (Factor Activity from patient tube / Factor Activity in control tube) x 100.
Understanding residual activity critical for determining patient treatment efficiency and response to factor administration.

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Description

Test your knowledge on coagulation factor deficiency using the substitution test method. Practice identifying missing factors based on APTT correction with aged serum and no correction with adsorbed plasma.