Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Heme Board Review Question Notes > Coagulation Missed Questions > Flashcards

Coagulation Missed Questions Flashcards

1
Q

Which vWD causes platelet aggregation and

thrombocytopenia in response to DDAVP ?

A
  • Type 2B
  • Gain of function that causes it to bind to GP IB/V/IX more readily
  • usually a transient thrombocytopenia that does not cause bleeding or thrombosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the main defect in vWD type 2A ?

A
  • mutation in the vWF protease cleavage site
  • leads to increased enzymatic cleavage
  • lack of high and intermediate vWF multimers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the main defect in vWD type 2M ?

A
  • caused by a loss of function mutation in the vWF binding site on GP IB/V/IX
  • leads to decreased binding of vWF to platelets
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the defect in vWD type 2N?

A
  • mutation in the factor VIII binding site on vWF
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the mechanism of HIT ?

A
  • antibodies to platelet factor four complexed to Heparin occur
  • antibodies can form in response to unfractionated heparin and LMW Heparin, although less likely because of the smaller molecule size
  • generally presents as an unexplained thrombocytopenia 4-14 days after heparin administration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a Latex Immunoassay used for

in coagulation testing ?

A
  • used for the quantitative detection of plasma proteins
  • Process:
    • latex is sensitized with reactant and the specimen
    • provides a quantitative measurement by using light detection methods or turbidimetry (light absorption) or nephelometry (light scattering) to detect resultant antibody-antigen complexes
    • IMP:
      • this test does NOT measure activity levels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a chromogenic assay used for ?

A
  • it is a qualitative assay, meaning it checks function
  • it is a good first step in evaluation of bleeding when there is normal PT, aPTT, and fibrinogen levels
  • how do the assays work:
    • chromogenic assays provide all components of the coagulation cascade needed to clot except for the factor being measured
    • the end point is cleavage of synthetic substrate thorugh enzymatic reaction
      • this is determined colorimetrically
      • the assay precisely measures the activity of the protein being tested
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What sort of coagulation issue should be suspected in a newborn with

bleeding (post circumcision etc) with normal PT, aPTT, and fibriongen levels?

A
  • Factor XIII functional deficiency or less likely quantitative deficiency
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is PCR used in coagulation testing ?

A
  • it is NOT used to measure activity or levels of coagulation factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does a clotting assay work in coagulation testing ?

A
  • these are modified PT and aPTT designed to make the factor of interest the rate-limiting step
  • How it works:
    • test plasma is compared with control plasma
    • the amount of correction is then measured
  • clot based assays give a broader view of the factor of interest function
  • IMP
    • activity of factor XIII cannot be detected by clot-based methods
  • Clot stability is assessed through the use of 5M of urea or 1% monochloracetic acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does an ELISA assay work

in coagulation testing ?

A
  • measures quantitative levels of plasma proteins
  • fluorescent labeled antibody is combined with the patient sample, then a labeled detection antibody is added
  • the level of fluorescence, luminscence or optical density is then measured to provide an accurate level of the protein of interest
  • IMP
    • this test does not measure activity levels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the different type of factor defects ?

A
  • Type I: quantitative with reduced or absent amounts of factor
  • Type II: qualitative with decreased activity despite normal numbers
  • Acquired defects can behave as type I or II
  • IMP
    • when choose a PT or aPTT clot based assay vs. chromogenic assay remember levels of other proteins can affect the clot based assay results while chromogenic is not affected
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What can be a cause of Heparin resistance ?

A
  • AT deficiency
    • inherited or acquired
    • AT deficiency affects Heparin therapy because heparin is not able to accelerate AT effectively if AT is present in low amounts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which factors are inactivated by Heparin binding to Antithrombin ?

A
  • IIa (thrombin)
  • IXa
  • Xa
  • XIa

Note: aPTT is usually used to monitor UFH therapy. If 25,000 to 35,000 IU of Heparin is administered in a 24 hour period without much affect on aPTT, then resistance should be considered.

IMP: if anti-Xa is elevated out of proportion to the measured aPTT then Heparin resistance should be considered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are common causes for Heparin resistance ?

A
  • elevated factor VIII activity (acute phase reactant)
  • congenital or acquired AT deficiency
  • increased Heparin clearance
  • increased Heparin binding to proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the treatment for Heparin resistance ?

A
  • switching to alternative anticoagulant
    • Argatroban
  • also can administer AT through infusion of plasma or AT concentrates
  • monitoring with anti-Xa activity instead of aPTT
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the function of Heparin cofactor II?

A
  • heparin cofactor II binds to Heparin which leads to inactivation of factor IIa
  • increased cofactor activity does NOT cause heparin resistance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which hemoglobinopathies are associated with

sickling of the peripheral blood ?

A
  • SS
  • SC
  • SD
  • SO
  • S/Beta Thalassemia

Note: Hb SG-Philadelphia behaves like a sickle cell trait.

Note: sickle cells are irreversibly damaged red cells. Boat cells are reversibly distorted and resume their discoid shape with oxygenation.

19
Q

What is the treatment for acquired Factor X deficiency

due to systemic amyloidosis ?

A
  • FFP or prothrombin complex concentrates
  • Acquired Factor X deficiency can be seen in:
    • vitamin K deficiency or liver disease
      • but in these instances it is usually not isolated (II, VII, IX, etc)
    • respiratory infections
    • thymoma
    • malignancies (RCC, adrenal adenocarcinoma, AML)
    • aquired inhibitors or congenital deficiencies are rare
20
Q

What does microhematocrit measure and how ?

A
  • determines the PCV (percentage of red cells in whole blood) using a potassium EDTA whole blood sample
  • how it works:
    • a small volume of blood is taken up by the capillary action into a fixed bore capillary tube
    • end of the tube is heat sealed and centrifuged for 5-10 minutes at a high rate
    • sample separates into red cells, white cells, platelets, and plasma layer
    • percentage of the column occupied by red cells (linear distance) compared with the total column is the packed cell volume
21
Q

What factors affect the microhematocrit PCV ?

A
  • centrifugation time
  • centrifugal force
  • red cell size and deformability
  • increased ESR
  • anticoagulant type
  • deoxygenation of Hgb
22
Q

How is the PCV by microhematocrit affected by SS disease, B-Thal,

decreased centrifugation time, increased ESR, and decreased centrifugal force ?

A
  • SS Disease
    • PCV is increased by microcytosis, SS disease and other causes of decreased RBC deformability
  • B-Thal
    • does not affect PCV
  • Decreased centrifugation time
    • PCV is increased because of excess plasma trapping
  • Increased ESR
    • causes falsely low PCV due to decreased plasma trapping
  • Decreased centrifugal force
    • PCV is increased because of incommplete reduction of plasma trapping
23
Q

What is the inheritance pattern of

Bernard Soulier syndrome and what are the main defects ?

A
  • Autosomal Recessive
  • defect in GP Ib/V/IX complex
  • Symptoms:
    • bleeding
    • thrombocytopenia
    • large platelets
    • bleeding often starts in childhood with frequent nosebleeds, gum bleeding, and easy bruising
24
Q

How is the diagnosis of Bernard

Soulier made ?

A
  • platelets fail to aggregate with ristocetin
  • diagnosis can be confirmed with flow cytometry to analyze GPIb-alpha surface density
25
Q

What is stored in the Weibel-Palade

bodies of endothelial cells ?

A
  • vWF and P-selectin
  • other proteins: IL-8, endothelin, tPA
  • Weibel Palade bodies are secretory organelles found within endothelial cells
    • they are oval or elongated with a whorled or fingerprint like appearance on EM
  • vWF
    • acts in primary hemostasis by binding platelets to the subendothelium and also stabilizes factor VIII in plasma
  • P-selectin
    • participates in leukocyte adhesion
26
Q

Which is the preferred anticoagulant for a

CBC specimen ?

A
  • K2EDTA
  • Note:
    • K3-EDTA can cause cell shrinkage and a slight dilution of the sample
    • Na-Heparin: causes white cell clumping
    • Na-Citrate: dilutes the blood sample and can also cause cell shrinkage

IMP: cell shrinkage causes a lower MCV and HCT

27
Q

When diagnosing antiphospholipid antibody

syndrome what must be demonstrated ?

A
  • antiphospholipid antibodies must be detected on two or more occasionas at least 12 weeks apart
  • this is an acquired autoimmune condition
  • symptoms include:
    • thrombosis
      • microvascular thrombosis usually manifest as catastrophic APS syndrome
    • pregnancy loss
    • persistent APS antibodies
28
Q

What are the clinical criteria for

APS Syndrome ?

A
  • vascular thrombosis: one or more episodes of venous, arterial or small vessel
  • pregnancy morbidity
    • one or more unexplained deaths of normal fetus at or. >10 weeks
    • one or more preterm births of normal neonate before 34th week of gestation due to eclampsia or pre-eclampsia
    • 3 or more unexpalined consecutive spontaneous miscarriages before 10th week with other possible causes excluded (hormonal, chromosomal etc)
29
Q

What are the laboratory criteria

for APS Syndrome ?

A
  • LAC present in plasma on 2 or more occasions, 12 weeks apart of IgG or IgM isotype present at medium or high titer
  • Anti-B2 glycoprotein 1 antibody of IgG or IgM isotype in serum or plasma on 2 or more occasions at least 12 weeks apart
  • Prolongation of Phospholipid dependent tests on 2 or more occasions
  • Demonstration of presence of an inhibitor
  • Demonstration of the phospholipid dependence inhibitor

Note: LAC activity is an in vitro phenomenon that is prolongation of phospholipid dependent coagulation tests and not a specific inhibitor to coagulations factors

30
Q

What are phsopholipid based tests that

can be used to test for LAC antibodies ?

A
  • should always use two or more tests when testing for APS
  • Tests
    • low phospholipid concentration PTT
    • dilute Russell viper venom time
    • kaolin clotting time
    • dilute PT
  • Confirmator testing
    • use a high phospholipid concentration test or LAC-insensitiv test to demonstrate phospholipid dependence
31
Q

What test is used to look for

aCL and anti-B2-glycoprotein antibodies ?

A
  • ELISAS
32
Q

What lab findings can suggest an

alpha thalassemia trait ?

A
  • presence of microcytosis
  • normal hemoglobin fractions (normal A2 and F)
  • normal iron studies (may be denoted by normal platelets and Ferritin levels)

Note: alpha thalassemias are most commonly caused by deletion of 1 or more alpha globin genes

33
Q

How does delta-B Thalassemia present

with lab findings ?

A
  • microcytosis by MCV
  • elevated Hgb F
  • normal Hgb A2
34
Q

How does Hgb E trat present in the lab ?

A
  • Microcytosis
  • there is peak that elutes on HPLC in the A2 window

IMP: Hgb Lepore also presents in this way on HPLC

35
Q

How does B-Thalassemia trait present

by HPLC ?

A
  • microcytosis
  • elevated Hgb A2
36
Q

What are the percentages of hemoglobins by HPLC

for Sickle cell trait and S/B Thalassemia ?

A
  • Sickle cell trait:
    • Hgb A. > Hgb S fraction
  • S/B Thal
    • Hgb S > Hgb A
37
Q

What are antifibrinolytic medications ?

A
  • aminocaproic acid
  • aprotinin
  • tranexamic acid
38
Q

What are Howell Jolly Bodies composed of. ?

A
  • DNA
  • think …..DNA is long and complex just like the name Howell Jolly Body
39
Q

What is the size and distribution of the RBCs

on the RBC histogram in treated B 12 def, end stage liver disease,

pseudothrombocytopenia, B-thal trait, and treated Fe def anemia ?

A
  • Treated B12
    • macrocytosis
  • ESLiver Dz
    • macrocytosis
  • Pseudothrombocytopenia
    • platelet clumps are small and should not have a large distribution of microcytic cells
  • B Thal trait
    • uniformly distributed microcytic cells
  • Fe Def anemia
    • variable distribution with microcytes and the macrocytes represent reticulocytes that are being pushed out
40
Q

What is the Coulter method for detection of

cells in the hematology analyzer ?

A
  • electrical-impedence method
  • cells are suspended in an electrolyte solution and passed through an aperture with an electrical field around it
    • measures numbers of cells as well as size
    • size is X axis, number of cells is Y axis
  • IMP
    • a dimorphic red cell histogram corresponds to two RBC populations
    • dimorphic RBC s can represent treated Fe deficiency anemia, transfused RBCs, treated megaloblastic anemia, sideroblastic anemia, hemolytic anemias
41
Q

What is the advantage of the red cell histograms ?

A
  • the MCV may be normal in the presence of dimorphic red cell populations
42
Q

How are Fe deficiency anemia and B-Thalassemia

differentiated on a RBC cytogram ?

A
  • B thal trait
    • microcytosis (downward shift) but the hemoglobin content per cell does not decreased
  • Fe Def Anemia
    • microcytosis and decreased hemoglobin content (leftward shift)

Note: sickle cell disease is usually normochromic, normocytic anemia

43
Q

What are some general considerations with

Factor V Leiden ?

A
  • inherited thrombophilia disorder with increased risk of VTE
  • mutation of Factor V at 1691 G* APC is 10x slower at inactivating FVL than WT
  • most common genetic risk factor for VTE, ~5% of caucasians

Heme Board Review Question Notes (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions