Coagulation & Platelet Disorders Flashcards
What does PT test?
Function of common & extrinsic pathway (factors I, II, V, VII, X). Inc in a defect
What does PTT test?
Function of common & intrinstic pathway (all factors except VII & XIII). Inc in defect
What is the MC coagulation disorder?
Hemophilia A
What is increased in Hemophilia A or B?
PT
What is the defect in Hemophilia A & B?
Intrinsic pathway coagulation defect
What is deficient in Hemophilia A?
Factor VIII
What is deficient in Hemophilia B?
Factor IX
What are the sx of hemophilia A & B?
- Macrohemorrhages
- Hemarthroses (bleeding into joints)
- Easy bruising
- Inc PTT
What is increased in Vitamin K?
PT & PTT
What is the defect in Vitamin K def?
General coagulation defect
Which factor synthesis is dec in Vitamin K def?
Factors II, VII, IX, X, protein C & S
What do defects in platelet plug formation lead to?
Inc bleeding time (BT)
What are the signs/sx of Platelet ABN?
- Microhemorrhage
- Mucous mem bleeding
- Epixtaxis
- Petechiae
- Purpura
- Inc bleeding time
- Possible dec platelet count (PC)
What are the lab features of Bernard-Soulier synd?
- Dec platelet count
- Inc bleeding time
What is the defect in Bernard-Soulier synd?
Platelet plug formation
What is decreased in Bernard-Soulier synd?
Dec GpIb→ defect in platelet-to-vWF adhesion
What are the lab features of Glanzmann’s thrombasthenia?
- Inc bleeding time
- Blood smear shows no platelet clumping
What is the defect in Glanzmann’s thrombasthenia?
Defect in platelet plug formation
What is decreased in Glanzmann’s thrombasthenia?
GpIIb/IIIa→ platelet-to-platelet aggregation
What are the lab features in Idiopathic thrombocytopenic purpura (ITP)?
- Dec platelet count
- Inc bleeding time
- Inc megakaryocytes
What is the defect in ITP?
Anti-GpIIb/IIIa Ab’s→ splenic macrophage, consumption of platelet/Ab complex
What is dec in ITP?
Platelet survival
What are the lab features of Thrombotic thombocytopenic purpura (TTP)?
- Dec platelet count
- Inc bleeding time
- Schistocytes
- Inc LDH
What is deficient in TTP?
ADAMTS 13 (vWF metalloprotease)→ dec degradation of vWF multimers
What is the pathogenesis of TTP?
Inc large vWF multimers→ inc platelet aggregation & thrombosis
What is dec in TTP?
Platelet survival
What are the sx of TTP?
- Neurologic sx
- Renal sx
- Fever
- Thrombocytopenia
- Microangiopathic hemolytic anemia
What are the lab features in von Willebrand’s dz?
- Inc bleeding time
- Normal or inc PTT
What is the intrinsic pathway coag defect in Von Willebrand dz?
Dec vWF→ normal or inc PTT (depends on severity; vWF acts to carry/protect factor VIII)
What is the defect in platelet plug formation in von Willebrand’s dz?
Dec vWF→ defect in platelet-to-vWF adhesion
What is the MC inherited bleeding disorder?
von Willebrand’s dz
(AD)
How is von Willebrand’s dz dx?
Ristocetin cofactor assay
What is the tx of von Willebrand’s dz?
DDAVP (desmopressin) which releases vWF stored in endothelium
What are the test features in DIC?
- Dec platelet count
- Inc bleeding time
- Inc PT
- Inc PTT
What is DIC?
Widespread activation of clotting leads to a fef in clotting factors, which creates a bleeding state
What are the causes of DIC?
- Sepsis (gram-neg)
- Trauma
- Obstetric complications
- Acute pancreatitis
- Malignancy
- Nephrotic synd
What are the lab features in DIC?
- Schistocytes
- Inc fibrin split products (D-dimers)
- Dec fibrinogen
- Dec factors V & VIII
What is Factor V Leiden dz?
Production of mutant factor V that is resistant to degradation by activated protein C
What is the MCC of inherited hypercoagulability in whites?
Factor V Leiden dz
What is Prothrombin gene mutation?
Mutation in 3’ untranslated region→ inc production of prothrombin→ inc plasma levels & venous clots
What is Antihrombind def?
Inherited def of antithrombin
What is blunted after heparin administration in Antithrombin def?
Inc in PTT
What is Protein C or S def?
Dec ability to inactivate factors V & VIII
What does Protein C or S def inc risk of?
Thrombotic skin necrosis w/ hemorrhage following administration of warfarin
What is the dosage effect of Packed RBCs?
Inc Hb & O2 carrying capacity
What is the clinical use of Packed RBC’s?
- Acute blood loss
- Severe anemia
What is the dosage effect of Platelets?
Inc platelet count (Inc -5,000/mm3/unit)
What is the clinical use of Platelets?
Stop significant bleeding (thrombocytopenia, qualitative platelet defects)
What is the dosage effect of Fresh frozen plasma?
Inc coagulation factor levels
What are the clinical uses for Fresh frozen plasma?
- DIC
- Cirrhosis
- Warfarin overdose
What is the dosage effect of Cryoprecipitate?
Contains fibrinogen, factor VIII, factor XIII, vWF & fibronectin
What are the clinical uses of Cyroprecipitate?
Tx coagulation factor def involving fibrinogen & factor VIII
What are the risks of blood transfusion?
- Include infection transmission (low)
- Transfusion reactions
- Iron overload
- Hypocalcemia (citrate is a Ca chelator)
- Hyperkalemia (RBC may lyse in old blood unit)
