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Hemotology II
For the Heme/Onc exam, 11/25/09
39
Medical
Graduate
11/23/2009

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Cards

Term
What are the three systems for anticoagulation (assume endothelium is intact)?
Definition
  1. Protein C (thrombin --> thrombomodulin, which activates C, which along with Protein S, inactivates Va and VIIIa)
  2. Antithrombin III (neutralizes activated enzymes with heparan sulfate, target of heparin)
  3. Fibrinolytic system (tPa activates plasminogen into its plasmin form)
Term
Which glycoprotein on platelets is responsible for binding fibrinogen? How is it activated? In which disease is it defficient?
Definition

GpIIb-IIIa.

 

When platelets are activated, they release ADP, which binds to the glycoprotein. This causes conformational change and, subsequently, activation. It is deficient in Glanzmann disease.

Term
What is the most immediate step in coagulation?
Definition
Arterial constriction due to NO.
Term
What are the consequences of a von Willenbrand factor deficiency?
Definition
No platelet adherence (expect petechiae), diminished Factor VIII (vWF is a carrier), but not enough to cause hemophilia.
Term
What proteins are Vitamin K-dependent? Which drug would target them?
Definition
Factors II, VII, IX, X, as well as protein C and S. Warfarin
Term
What is DIC? What are some of the major causes? What is the treatment?
Definition

Excessive, dysregulated activation of coagulation system. Factors and platelets are consumed. Thrombosis in mild cases, hemorrhage in severe.

 

Common causes are sepsis from G- bacteria, and obstretical complications (necrotic tissue from placenta consumes clotting factor)

 

Treat underlying condition

Term

Identify the most likely causes:

  1. Patient is factor VII and X deficient, with normal V and VIII
  2. Patient is factor V, VII, X deficient, with normal VIII
  3. Patient is factor V, VII, VIII, X deficient
Definition
  1. Vitamin K deficiency
  2. Liver disease (factors all made in liver, but VIII is preserved in cirrhosis)
  3. DIC
Term
How does Vitamin K activate its various factors? What could be some possible reasons for Vitamin K deficiency?
Definition

Performs carboxylation that allow calcium binding.

 

Poor diet (lacking in leafy green vegatables), broad-spectrum antibiotics (bacteria responsible for Vit. K absorption)

Term
What are "antiplatelet" factors?
Definition
PGI2 and NO inhibit adherence. ADPase prevents ADP mediated platelet aggregation.
Term
Where are venous thrombi typically initiated?
Definition
Typically form in the venous valve. Inflames vein, leading to thrombophlebitis, and consequently swelling, pain, erythema and loss of funciton.
Term
What are some causes of the "hypercoagulable state"?
Definition

Feeling hyper? Pick up some meds at the IIIrd CVS in Beverly Hills 20210.

  1. Antithrombin III deficiency
  2. Protein C or S deficiency
  3. Factor V:Leidin (common mutation that prevents Protein C mediated degradation of factor V)
  4. Prothrombin gene mutation (prothrombin 20210- excessive half-life of prothrombin mRNA)
Term
What is the treatment for DVT?
Definition

Initial period (5 days) - Heparin to reduce new fibrin deposition and allow natural lysis.

 

Chronic (6-12 months) - Warfarin to prevent recurrence

Term
What are some of the postphlebitic/post-thrombotic syndromes?
Definition
Healing process degrades venous valves, leading to venous incompetence, reduced venous blood return, leg edema, risk of thrombosis, skin ulcers.
Term
What lab values would expect to see in the case of lupus antiphospholipid?
Definition
Increased PTT in vitro, even though the disease is a hypercoagulative in vivo.
Term
Which factor binds to vWF? What would be the consequence of losing this receptor?
Definition
GP Ib/V/IX. Loss would prevent platelet adherence (as in the case of Bernard Soulier syndrome)
Term
Which enzyme does asparin target that prevents platelet aggregation? Which pertinent product of that enzyme is consequently decreased?
Definition
COX-2; thromboxane A2.
Term
What is the role of the spleen in platelet sequestration?
Definition

Normally, 1/3 platelets sequestered.

 

Splenomegaly can lead to 90% sequestration, although typically does not results in a plt count below 50k. Cirrhosis, and portal htn can lead to thrombocytopenia.

Term
Which causes of thrombocytpoenia are typically associated with bleeding?
Definition
  1. ITP (immune mediated platelet destruction)
  2. Drug-induced thrombocytopenia
Term
What causes of thrombocytopenia are associated with thrombosis?
Definition
  1. TTP (thrombotic cytopenia purpura, due to ADAMTS13/vWF cleaving protein deficiency)
  2. HIT (heparin induced thrombosis, antibodies directed against PFIV-Heparin fusion protein leads to platelet activation)
  3. DIC (uncontrolled prudction of thrombin and fibin deposition)
Term
Patient presents with anemia, petechia, thrombocytopenia, headache and fever. Urinalysis shows proteinuria. What is the most likely diagnosis? What would you expect to see in the peripheral blood smear? What other lab results are expected?
Definition

TTP

 

Fragmented/cleaved cells (schistocytes)

[image]

 

High LDH and retic count.

Term
What is the most likely mechanism for TTP? Treatment?
Definition

Either congenital deficiency in ADAMST13 or autoimmune response directed against it. The protein is produced on endothelial cells, and cleave vWF. Without cleavage, large multimers cause spontaneous thrombi.

 

Plasmapherisis removes these large multimers and potentially removes antibodies directed against ADAMST13. It can also supply missing vWF protease.

Term
What labs would confirm DIC?
Definition
Thrombocytpoenia, elevated PT/PTT, decreased fibrinogen and increased D-dimer
Term
What is the most common treatment of ITP?
Definition
Steroids. For immediate relief, IVIG and anti-RH (Winrho) can temporarily increase platelets.
Term
What does an elevated hemoglobin A2 indicate?
Definition
B-Thalassemia
Term
What is the role of hepcidin, and in which pathological disease would you expect to see it?
Definition
Downregulates iron export, sequestering iron in liver. Seen in anemia of chronic inflammatory disease.
Term
What does increased transferrin (TIBC >400 ug/dL) indicate?
Definition
Increased iron binding capacity due to depleted iron stores.
Term
How would you distinguish iron deficiency anemia from ACD?
Definition

Iron deficiency generally more hypochromic, microcytic.

 

Definitive assay is transferrin receptor assay (increased Tf in iron deficiency)

 

Also, ACD typically responds well to EPO

Term
What can trigger increase in transferrin receptor?
Definition
Increase in erythroid component of BM (hemolytic anemia, thalassemia) or iron deficiency
Term
What is pagophagia, and what does it indicate?
Definition
Compulsive ice eating, a sign of iron deficiency
Term
Which disease increases RBC adhesion to vascular endothelial cells, causing obstruction and inflammation?
Definition
Sickle cell
Term
What role does HbF take in sickle cell disease?
Definition
3-20% of RBCs in SS have HbF. Believed to prevent sickling. Higher HbF is correlated with better prognosis; hydroxyurea is believed to work by increasing HbF.
Term
What is one major way sickle cell differs from other hemolytic anemias?
Definition
Autosplenectomy (diminished spleen size)
Term
What are possible clinical complications of sickle cell anemia?
Definition
  1. Vascular obstruction (stroke, retinal disease, necrosis of bones)
  2. Renal damage (papillary necrosis)
  3. Priapism (painful, prolonged erection)
  4. Osteomyletis from salmonella infection
  5. Ankle ulcers
Term
24 year old patient comes into your office directly from a flight across the country, reporting abdominal pain unlike anything he experienced before. Work up shows splenic infarction. What is the most likely cause of this seemingly spontaneous symptom?
Definition
Sickle cell carrier (sickle cell trait) triggered by high altitude, low pO2
Term
What are two theories explaining how thalassemia/hemoglobinopathies heterozygotes are selectively advantaged over HbA homozygotes?
Definition
  1. Plasmodium induce sickling in infected erythrocytes, leading to targeted removal by spleen.
  2. Limited oxygen availability in hemoglobin-deprived erythrocytes prevent plasmodium proliferation.
Term
What are the diagnostic features of hemoglobin C?
Definition
  1. Presents as hemolytic anemia (hematocrit ~30%).
  2. Target cells and spherocytes present (also present in carriers).
  3. Crystals are observed in RBCs.
  4. Generally well.
Term
What can be used to distinguish hemoglobin SC from sickle cell?
Definition
  1. Slightly highe rhematocrit (28-33%)
  2. Splenomegaly
  3. Presence of target cells and spherocytes in addition to sickle cells.
Term
In what circumstances might you notice a heterozygote with an unstable hemoglobin mutation?
Definition
When exposed to drugs with redox properties (anti-malarials, sulfa drugs) or contract fevers, they will undergo hemolytic episodes
Term
What are the hallmarks of beta thalassemia?
Definition
  1. Microcytic, hypochromic peripheral RBCs if just carrier.
  2. In untreated major intramedullary hemolysis, ineffective erythropoiesis and extramedullary hematopoeisis (bone abnormalities)
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