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Block 6 > Heme/ Oncology > Flashcards

Heme/ Oncology Flashcards

1
Q

What does thrombocytopenia mean?

A

Low platelets

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2
Q

What is primary hemostasis? What is secondary hemostasis?

A

Primary hemostasis- formation of a weak platelet plug.
Secondary hemostasis- stabilization of the platelet plug by the coagulation cascade.

(Hemostasis= blood clotting)

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3
Q

Disorders of primary hemostasis are usually due to abnormalities in what?

A

Platelets

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4
Q

What’s the difference between quantitative and qualitative primary hemostasis disorders?

A

Quantitative- you don’t have enough platelets

Quantitative- you have enough platelets, but the quality of them is bad

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5
Q

What does “epistaxis” mean?

A

Nosebleeds

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6
Q

What are clinical symptoms of primary hemostasis disorders?

A

(Primary hemostasis is formation of a weak platelet plug, so these disorders are due to abnormalities in platelets.)
Mucosal and skin bleeding.

Mucosal bleeding- epistaxis (nosebleeds), hemoptysis (coughing up blood), GI bleeds, hematuria (peeing out blood), menorrhagia (heavy menstrual bleeding), intracranial bleeding if severe.

Skin bleeding- petechiae, purpura, ecchymoses, easy bruising.

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7
Q

Patient presents with epistaxis (nosebleeds), hematuria, petechiae on skin, and bruises all over. What category of conditions should you think of to diagnose?

A

Primary hemostasis disorders. Because the patient is presenting with mucosal and skin bleeding symptoms, which is classic for platelet abnormalities (inability to form weak platelet plug to clot).

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8
Q

Why do patients with primary hemostasis present with mucosal and skin bleeding?

A

Primary hemostasis= formation of weak platelet plug. Primary hemostasis disorders involve platelet dysfunction. If not enough platelets or poor quality platelets—> not enough clotting—> bleeding.

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9
Q

Petechiae is a sign of what?

A

Thrombocytopenia (low platelet count)
*not usually seen in a primary hemostasis disorder that is due to poor quality platelets, quantitative (just seen in one due to lack of platelets, qualitative)

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10
Q

What is a normal platelet count?

A

150-400 K/uL (<50 leads to symptoms)

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11
Q

What is a normal bleeding time?

A

2-7 minutes

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12
Q

The following laboratory studies can be helpful in diagnosing a primary hemostasis disorder in a patient. Explain how so.

  1. Platelet count
  2. Bleeding time
  3. Blood smear
  4. Bone marrow biopsy
A
  1. Platelet count- if quantitative (not enough platelets), will be low
  2. Bleeding time- if quantitative (not enough platelets) or qualitative (poor quality platelets) will be high (you bleed out for a longer time before body stops the bleeding by clotting)
  3. Blood smear- so you can see the number and size of platelets
  4. Bone marrow biopsy- so you can see megakaryocytes, which are the precursors to platelets
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13
Q

What is Immune Thrombocytopenic Purpura (ITP)?

A

(Quantitative primary hemostasis disorder, meaning there’s not enough platelets to form a platelet plug to clot)
Autoimmune problem where you have IgG auto-antibodies against platelets (for example, against the Gp2b/3a receptors on platelets that help platelets cross-link to aggregate and form a plug). This is the most common cause of thrombocytopenia in adults and children!!

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14
Q

What is the most common cause of thrombocytopenia in adults and children?

A

Immune Thrombocytopenia Pupura (ITP)
*this is a quantitative primary hemostasis disorder (not enough platelets). It is an autoimmune problem where you have auto-antibodies against platelets (like their GP2a/3b receptors).

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15
Q

A patient’s labs reveal thrombocytopenia. Without any further information, what is the most likely diagnosis?

A

Immune Thrombocytopenia Pupura (ITP). This is the most common cause of thrombocytopenia (low platelet count) in adults and children!
*this is a quantitative primary hemostasis disorder (not enough platelets). It is an autoimmune problem where you have auto-antibodies against platelets (like their GP2a/3b receptors).

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16
Q

Explain the pathophys of Immune Thrombocytopenic Purpura (ITP).

A

*This is a quantitative primary hemostasis disorder (not enough platelets) and is the most common cause of thrombocytopenia.
It is an autoimmune problem in which auto-antibodies are produced by plasma cells in the spleen and attack platelets. Then, splenic macrophages eat them up—> thrombocytopenia (low platelet count).

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17
Q

Regarding Immune Thrombocytopenia Purpura (ITP), what is the difference between the acute and chronic forms?

A

remember that ITP is a quantitative primary hemostasis disorder (not enough platelets so can’t form platelet plug to clot well) and it’s the most common cause of thrombocytopenia (lack of platelets)

Acute- in kids, after a virus, self-limited
Chronic- in adults (usually women of childbearing age), can be primary or secondary (SLE), IgG can cross the placenta so can cause thrombocytopenia in baby if pregnant mom has it

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18
Q

Patient has dec platelet count, normal PT/ PTT, and inc megakaryocytes on bone marrow biopsy. What are you thinking?

A

Quantitative primary hemostasis disorder—Immune Thrombocytopenia Purpura (ITP) or Microangiopathic Hemolytic Anemia (not enough platelets to form platelet plug to clot well).

Bone marrow increases megakaryocytes (platelet precursors) to try to compensate for dec platelets. Normal PT/ PTT because it is a PRIMARY hemostasis disorder, so it’s a problem with weak platelet plug formation, not a problem with coagulation factors in secondary hemostasis).

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19
Q

In a primary hemostasis disorder, will you see increased PT/ PTT time?

A

No. PRIMARY, so it’s a problem with weak platelet plug formation, not with secondary hemostasis, or coagulation cascade to stabilize the platelet plug. No problem with coagulation factors= no change in PT/ PTT.

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20
Q

What is the treatment for Immune Thrombocytopenia Purpura (ITP)?

A

Corticosteroids.
Other options: IVIg (throw splenic macrophages this “bone” so they won’t go after the Ig bound to platelets), splenectomy (eliminates the primary source of antibody and the site of platelet destruction).

*page 32 Pathoma

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21
Q

What is microangiopathic hemolytic anemia? Explain the 2 sub-types (what conditions they are seen in, pathophys).

A

Quantitative primary hemostasis disorder (not enough platelets to form weak platelet plug to help clot).
Seen in thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS).

TTP—> autoantibody—> dec ADAMTS13 enzyme that normally cleaves vWF for degradation—> abnormal platelet clumping (platelet microthrombi)—> dec platelets where you need them at injury site so you get thrombocytopenia and the platelet microthrombi shear RBCs giving you shistocytes (hemolytic anemia).

HUS from E. Coli 0157:H7 (or Shigella)—> toxin damages endothelial cells—> platelets clump up (platelet microthrombi)—> dec platelets where you need them at injury site so you get thrombocytopenia and the platelet microthrombi shear RBCs giving you shistocytes (hemolytic anemia).

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22
Q

Kid ate some undercooked hamburger. Now has a low platelet count. What’s going on?

A

Hemolytic Uremic Syndrome from E.Coli.

HUS from E. Coli 0157:H7—> toxin damages endothelial cells—> platelets clump up (platelet microthrombi)—> dec platelets where you need them at injury site so you get thrombocytopenia and the platelet microthrombi shear RBCs giving you shistocytes (hemolytic anemia). *platelet thrombi also affect kidney vessels, giving you renal insufficiency.

*note that HUS falls under the category of microangiopathic hemolytic anemia, which is a type of quantitative primary hemostasis disorder (not enough platelets to form weak plugs to help clot).

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23
Q

In what condition would you see thrombocytopenia with inc bleeding time, normal PT/ PTT, anemia with shistocytes, and inc megakaryocytes?

A

Microangiopathic hemolytic anemia

You get abnormal platelet clumping into platelet thrombi—> shearing of RBCs (shistocytes, hemolytic anemia) and because the platelet clumping is abnormal, there are less platelets where they need to be at injury site so thrombocytopenia and bone marrow tries to compensate by inc megakaryocytes (platelet precursors) and normal PT/ PTT because it is a PRIMARY hemostasis problem (platelet problem), not secondary hemostasis problem (coagulation factor problem)

24
Q

Explain the following qualitative platelet disorders:

  1. Bernard-Soulier syndrome
  2. Glanzmann thrombasthenia
  3. Aspirin
  4. Uremia
A
  • Qualitative primary hemostasis disorders mean you have enough platelets, but they are bad quality so you can’t form a weak platelet plug to help clot well.
    1. Bernard-Soulier syndrome: genetic GPIb (receptor on platelets that helps it adhere to vessel wall vWF) deficiency—> impaired platelet adhesion.
    2. Glanzmann thrombasthenia: genetic GP2b/3a (receptor on platelets that helps it bind to other platelets)—> impaired platelet aggregation.
    3. Aspirin blocks COX—> platelets can’t make TXA2 (released in platelet degranulation to help promote aggregation)—> impaired platelet aggregation.
    4. Uremia (inc nitrogenous waste products held back in blood)—> messes up platelet function, impaired adhesion and aggregation.
25
Q

What is the meaning of a “secondary hemostasis disorder?”

A

Problem with the coagulation cascade factors—> problem with clotting/ stabilization of the weak platelet plug to clot

26
Q

Coagulation cascade factors are produced by what organ?

A

The liver. (They are produced in an inactive state—> float around blood and eventually get activated)

27
Q

Coagulation cascade factors are made in the liver, then get activated in the bloodstream. The presence of what 3 things are required in order for the coagulation factors to get activated?

A
  1. Exposure to an activating substance (tissue thromboplastin activates factor 7 in the extrinsic pathway and subendothelial collagen activates factor 12 in the intrinsic pathway).
  2. Phospholipid surface of platelets
  3. Calcium (derived from platelet dense granules)
28
Q

What are clinical features of secondary hemostasis disorders?

A

Deep tissue bleeding into muscles and joints (hemarthrosis) and rebleeding after surgical procedures (like circumcision and wisdom tooth extraction)

29
Q

What are clinical features of primary hemostasis disorders? Secondary hemostasis disorders?

A

Primary hemostasis—> mucosal and skin bleeding (nosebleeds, GI bleeds, coughing up blood, hematuria…petechiae, purpura, ecchymoses)

Secondary hemostasis—> Deep tissue bleeding into muscles and joints (hemarthrosis) and rebleeding after surgical procedures (like circumcision and wisdom tooth extraction)

30
Q

What is the inheritance pattern of Hemophilia A?

A

X-linked recessive (more common in males)

31
Q

Hemophilia A is an X-linked recessive deficiency of which clotting factor?

A

Factor 8 in the intrinsic pathway (remember Hemophilia “A” sounds like “8”)

32
Q

In Hemophilia A, do patients have a prolonged PT or PTT?

A

PTT because it is a deficiency in factor 8 of the INTRINSIC pathway (PTT for intrinsic, PT for extrinsic)

33
Q

Does PTT measure clotting time for the intrinsic or extrinsic pathway of the coagulation cascade? How about PT?

A

PTT is for intrinsic

PT is for extrinsic

34
Q

What is the difference between Hemophilia A and Coagulation Factor Inhibitor (both secondary hemostasis disorders)?

A

Hemophilia A is a genetic deficiency (X-linked recessive) of factor 8. Coagulation factor inhibitor is a deficiency of factor 8 (or another factor) due to an auto-antibody against factor 8.
*note: you can tell them apart by doing a mixing study (mix patients blood with healthy blood to see if PTT stays high or returns to normal).

35
Q

You can do a mixing study to tell Hemophilia A apart from Coagulation Factor Inhibitor. Explain.

A

Hemophilia A= deficiency of factor 8 due to genetic problem.
Coagulation factor inhibitor= deficiency of factor 8 due to auto-antibodies.
————————————————————-
Mixing study means you mix the patients blood (lacking factor 8) with normal, healthy blood and then measure the PTT.

Hemophilia 8–> PTT will return to normal because by mixing in good blood, you supply factor 8.

Coagulation factor inhibitor—> PTT will stay high bc even though you’re supplying factor 8, there are auto-antibodies that attack it right away so the problem still exists.

36
Q

What is the most common inherited coagulation disorder?

A

Von Willebrand Disease

37
Q

Patient has an unknown inherited coagulation disorder. What is it most likely?

A

Von Willebrand Disease. This is the most common inherited coagulation disorder!

38
Q

What is Von Willebrand disease.

A 
Secondary hemostasis (coagulation cascade) disorder and the most common inherited coagulation disorder. 
The most common subtype is autosomal dominant with decreased vWF. 
**you get impaired platelet adhesion, but it’s still consider a secondary hemostasis disorder, not primary, bc it messes with the coagulation cascade—vWF stabilizes factor 8, so in this disorder, factor 8 is unstable and PTT is prolonged.
39
Q

Mild mucosal and skin bleeding, inc bleeding time, inc PTT, and abnormal ristocetin test. Diagnosis?

A

Von Willebrand disease

**This is a secondary hemostasis (coagulation) disorder that is autosomal dominant and you have decreased vWF (normally stabilizes factor 8)—> unstable factor 8 and prolonged PTT. You have increased bleeding time due to poor platelet adhesion. Ristocetin is a molecule that can induce platelet aggregation. If you lack vWF, platelets won’t adhere/ stick even with the Ristocetin so the test is abnormal.

40
Q

What is the ristocetin test? Why is it abnormal in Von Willebrand disease?

A

Ristocetin is a molecule that can induce platelet aggregation (by causing vWF to bind to the platelet receptor GP1b).
Von Willebrand Disease—> lack of vWF—> platelets won’t adhere even with Ristocetin, so you get an abnormal ristocetin test.

41
Q

What is the treatment for Von Willebrand disease?

A

Desmopressin (ADH analog)
This increases vWF release from Wiebel-Palade bodies of endothelial cells (helps bc in this disease you have lack of vWF and therefore lack of platelet adhesion and lack of stabilization of factor 8 in the coagulation cascade).

42
Q

Vitamin K is activated by what enzyme in the liver?

A

Epoxide reductase

43
Q

In what patient populations do we most often see vitamin K deficiency (name 3)?

A
  1. Newborns (the infant GI tract isn’t full of as many bacteria and since some GI bacteria make vitamin K, this leads to vit K deficiency and it’s why we give babies a vit K injection)
  2. Patients on long-term antibiotics (kills vitamin K-producing bacteria in the gut)
  3. Malabsorption patients
44
Q

Explain why liver failure can cause abnormal secondary hemostasis.

A

(Secondary hemostasis= coagulation cascade problem)

The liver is the site where coagulation factors are made and the enzyme epoxide reductase in the liver activates vitamin K. SO, in secondary hemostasis, you get decreased production of coagulation factors and decreased activation of vitamin K (which further leads to decreased coagulation factors)—> coagulation cascade is not working well.
(**we can use PT to follow the effect of liver failure on coagulation)

45
Q

What effect can a large volume blood transfusion have on coagulation?

A

Large volume blood transfusion—> dilutes coagulation factors—> deficiency of coagulation factors, that is a secondary hemostasis disorder

46
Q

What is Heparin-induced thrombocytopenia?

A

You take Heparin for therapy and then develop platelet destruction (—> low platelets)

**Heparin forms a complex with platelet factor 4 (Hep—PF4) and antibodies attack that complex—> fragments of destroyed platelets may activate remaining platelets—> thrombosis (clotting)

47
Q

What is DIC (Disseminated Intravascular Coagulation)?

A

PATHOLOGICAL ACTIVATION OF THE COAGULATION CASCADE (the coagulation cascade gets activated when it’s not supposed to).

You get clotting in various places in blood vessels, blocking blood flow to organs—> ischemia. (TOO MUCH CLOTTING)
Since platelets and coagulation factors are used up to lay down random clots, there’s decreased platelets and coagulation factors in the bloodstream available to clot at injury sites where you need it—> when you get an injury, you bleed out. (TOO LITTLE CLOTTING)

48
Q

What laboratory findings (platelet count, PT/ PTT, fibrinogen, RBC findings, and fibrin split products) would you see in DIC (Disseminated Intravascular Coagulation)?

A

(DIC= pathological activation of the coagulation cascade)

  • Decreased platelet count (dec platelets floating around in the blood bc they clump up in thrombi on endothelial cells all over where they shouldn’t)
  • Increased PT/ PTT (coagulation factors are used up in the making of thrombi for random clots all over so there are less coag factors in the blood—> clotting problems in places where you need a clot)
  • Decreased fibrinogen (also gets consumed in the making of thrombi)
  • RBCs—> shistocytes (helmet cells) bc sheared by thrombi all over, so you get a microangiopathic hemolytic anemia
  • Elevated fibrin split products, especially D-dimer
49
Q

What is the best screening test for DIC?

A

Elevated D-dimer (a fibrin split product)

*tells you the entire coagulation cascade has been activated to the extent that you even activate the splitting of the cross-linked fibrin

50
Q

What factor resolves clots (does fibrinolysis)?

A

Plasmin

51
Q

HOW does plasmin resolve clots (do fibrinolysis)?

A

It cleaves fibrin and serum fibrinogen and destroys coagulation factors

52
Q

Disorders of fibrinolysis are due to what?

A

Plasmin overactivity (too much resolving of clots, excessive cleavage of fibrinogen)

Specific sub-types of fibrinolysis disorders:

  1. Radical prostatectomy- release of urokinase, which activates plasmin.
  2. Cirrhosis of liver- reduced production of alpha-2 anti-plasmin (so more activation of plasmin).
53
Q

Treatment for disorders of fibrinolysis is aminocaproic acid. What is its mechanism?

A

Blocks activation of plasminogen.

54
Q

What is a thrombosis?

A

A pathologic formation of an Intravascular blood clot (thrombus)

55
Q

What is the Virchow’s triad/ 3 things that put you at risk for thrombosis?

A
  1. Disruption of blood flow (like stasis bc you sit at a desk all day, MI, or aneurysm)
  2. Endothelial cell damage
  3. Hypercoagulable state

Block 6 (8 decks)

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