High Yield Topics-HemOnc Flashcards
Describe order of primary hemostasis (platelet plug formation)
- Endothelial cell damage/injury
- Endothelial cell releases vWF and collagen
- vWF binds to platelets via Gplb
- Platelets release ADP and Ca+2
- ADP binds to platelets via P2Y12 –> platelet aggregation
- Fibrinogen binds to platelets via Gpllb/Gpllla –> forms mesh
- platelet plug is temporary and is unstable –> can easily dislodge
What are the coagulation factors of common pathway for coagulation cascade (secondary hemostasis)?
10, 5, 2
*STUDY AID: “COMMON” math problem
2 x 5 = 10
What are the coagulation factors of intrinsic pathway for coagulation cascade (secondary hemostasis)?
12, 11, 9, 8 —> 10, 5, 2
- STUDY AID: write down 12-8 (exclude 10 b/c it’s already used for the common pathway)
What are the coagulation factors of extrinsic pathway for coagulation cascade (secondary hemostasis)?
7 –> 10, 5, 2
What test is used to measure intrinsic pathway?
PTT
- STUDY AID: intrinsic pathway has more coagulating factors –> PTT (more letters)
What test is used to measure extrinsic pathway?
PT
- STUDY AID: extrinsic pathway has less coagulating factors –> PT (less letters)
Which coagulation cascade pathway is slower?
Intrinsic
- STUDY AID: intrinsic pathway has more coagulating factors –> takes longer
What lab test is used to measure/monitor the effect of Heparin?
PTT
What lab test is used to measure/monitor the effect of Warfarin?
PT
What lab test(s) will be elevated when common pathway coagulating factors are deficient?
Both PT and PTT
What lab test will be elevated in platelet disorders?
Bleeding Time (BT)
Immune-mediated platelet destruction that is usually idiopathic and follows a recent infection; caused by antibodies against GpIIb/IIIa antibodies; it’s a diagnosis of exclusion
Idiopathic Thrombocytopenic Purpura (ITP)
Abnormal lab finding for ITP
↑ Bleeding Time
Thrombocytopenia
Clinical presentation of ITP
Increased bleeding
“BONE MARROW” biopsy finding for ITP
Megakaryocytes
- no schistocytes on PBS
A blood disorder due to deficiency of ADAMTS-13 that typically presents in females
Thrombotic Thrombocytopenic Purpura (TTP)
What is the function of ADAMTS-13?
A protease that degrades vWF
Describe the pathophysiology of TTP
ADAMTS-13 deficiency leads to ↓ degradation of vWF –> larger vWF (attached to endothelial cells) –> ↑ platelet adhesion and aggregation –> obstructed vessels –> destruction of RBCs as they pass through vessels –> intravascular hemolysis
Abnormal lab finding for TTP
↑ Bleeding Time
Thrombocytopenia
Clinical presentation of TTP
Thrombocytopenia Anemia (hemolytic; ↓ Hb, schistocytes) Renal Dysfunction (↑ creatinine) Fever Neurologic symptoms (confusion)
- STUDY AID: TTP
“ The Terrible Pentad”
Blood smear finding for TTP
Schistocytes
Toxin-mediated hemolysis that is caused by Shiga-like toxin from EHEC infection that typically presents in children
Hemolytic Uremic Syndrome (HUS)
Abnormal lab finding for HUS
↑ Bleeding Time
Thrombocytopenia
↑ Creatinine
Why does HUS present with ↑ Creatinine?
Toxin mainly affects the KIDNEY (glomerulus) by formation of platelet microthrombi (which causes obstruction and schistocytes)
Clinical presentation of HUS
Kidney failure, BLOODY diarrhea
Blood smear finding for HUS
Schistocytes
What E. coli serotype causes HUS?
O157:H7
A blood disorder caused by widespread clotting factor activation; caused by many factors (sepsis, snake venom, trauma, transfusion)
Disseminated Intravascular Coagulation (DIC)
Describe the pathophysiology of DIC
Sepsis/venom/trauma –> widespread clotting factor activation –> ↓ clotting factors, anticoagulant factors (protein C, protein S, antithrombin), platelets, and fibrinogen –> ↑ bleeding state
- STUDY AID: DIC
“ Damn I’m Clotting”
Abnormal lab finding for DIC
↑ Bleeding Time
↑ PT/PTT
↑ D-Dimer
Thrombocytopenia
↓ Fibrinogen
Clinical presentation of DIC
↑ Bleeding, sepsis
Blood smear finding for DIC
Schistocytes
A blood disorder caused by vWF deficiency; most common inherited bleeding disorder that can present with heavy menstrual bleeding and prolonged bleeding after tooth extraction
Von Willebrand Disease (VWD)
Inheritance pattern for Von Willebrand Disease (VWD)
Autosomal Dominant
- remember that it is most common type of inherited bleeding disorder!
Describe the pathophysiology of Von Willebrand Disease (VWD)
↓ vWF –> ↓ factor VIII activity & ↓ platelet adhesion to vWF –> ↑ PTT (can be normal) & ↑ BT
What coagulating factor is carried and protected by vWF?
Factor VIII
Tx for VWD
Desmopressin
MOA of Desmopressin in treating vWD
Desmopressin ↑ vWF release from endothelium
A bleeding disorder caused by GpIb deficiency
Bernard-Soulier Syndrome
What activity of platelet is defective in Bernard-Soulier Syndrome?
Platelet adhesion to vWF
Abnormal lab finding for Bernard-Soulier Syndrome
↑ Bleeding Time
Thrombocytopenia
Blood smear finding for Bernard-Soulier Syndrome
Large platelets
- same size as RBCs!
A bleeding disorder caused by GpIIb/GpIIIa deficiency
Glanzmann Thrombasthenia
What activity of platelet is defective in Glanzmann Thrombasthenia?
Platelet to platelet aggregation due to lack of fibrinogen mesh formation
Abnormal lab finding for Glanzmann Thrombasthenia
↑ Bleeding Time
Blood smear finding for Glanzmann Thrombasthenia
No platelet clumping
A bleeding disorder caused by factor VIII deficiency
Hemophilia A
A bleeding disorder caused by factor IX deficiency
Hemophilia B
A bleeding disorder caused by factor XI deficiency
Hemophilia C
Inheritance pattern for each type of Hemophilia
Hemophilia A: x-linked recessive
Hemophilia B: x-linked recessive
Hemophilia C: AR
Abnormal lab finding for all three types of Hemophilia
↑ PTT
- remember factors 8, 9, 11 are all intrinsic pathway coagulating factors!
A bleeding disorder caused by ↓ activity of factors II, VII, IX, X, protein C, protein S
Vitamin K deficiency
Abnormal lab finding for Vitamin K deficiency
↑ PTT
↑ PT
Conversion of fibrinogen to fibrin requires
Thrombin (factor IIa)
Aggregation of fibrin monomers to form fibrin mesh (fibrin polymer) requires
Factor XIIIa
Conversion of factor XIII to XIIIa requires
Thrombin (factor IIa)
- thrombin activates both fibrinogen and XIII
Protein C and S are regulatory ANTIcoagulant proteins that inhibit
Factors VIIIa and Va
A hyper-coagulability disorder caused by production of mutant factor V that is RESISTANT to degradation by protein C; presents with ↑ coagulating symptoms (DVT, pregnancy loss)
Factor V Leiden
MCV < 80 is ____ anemia
Microcytic
MCV=80-99 is ____ anemia
Normocytic
MCV > 80 is ____ anemia
Macrocytic
Anemia caused by low iron level
Iron deficiency anemia
Iron deficiency anemia is considered (micro/macro/normocytic) anemia
Microcytic
Iron Studies (Serum Iron, Ferritin, TIBC/Transferrin) for Iron deficiency anemia
Serum Iron: ↓
Ferritin: ↓
TIBC/Transferrin: ↑
Unique clinical presentations associated with Iron deficiency anemia
Pica and Koilonychia (nail spooning)
What disorder presents with a triad of esophageal webs, iron deficiency, and Dsyphagia?
Plummer-Vinson Syndrome
- STUDY AID: “call Plumber When I Diarrhea”
- W: Webs (esophageal)
- I: Iron Deficiency
- D: Dysphagia
Anemia caused by defective heme synthesis (porphyrin pathway), which leads to iron overload/accumulation in mitochondria
Sideroblastic Anemia
Genetic cause of Sideroblastic Anemia
ALA synthase deficiency
Acquired causes of Sideroblastic Anemia (2)
- Isoniazid (B6 deficiency)
2. Lead poisoning (inhibits ferrochelatase and ALA dehydratase)
Sideroblastic Anemia is considered (micro/macro/normocytic) anemia
Microcytic
Iron Studies (Serum Iron, Ferritin, TIBC/Transferrin) for Sideroblastic Anemia
Serum Iron: ↑
Ferritin: ↑
TIBC/Transferrin: ↓
Blood smear finding for Sideroblastic Anemia
ringed sideroblasts (basophilic stippling of iron granules in mitochondria of bone marrow cells)
Ringed sideroblasts are only visible by using what stain
Prussian blue stain (stain iron)
Anemia caused by defective hemoglobin production
Thalassemia
Anemia caused by defective synthesis of ALPHA subunit(s) of hemoglobin
α Thalassemia
Anemia caused by defective synthesis of BETA subunit(s) of hemoglobin
β Thalassemia
Normal Hb subunits
α2β2
- αα | ββ
__ (#) gene(s) deletion of alpha subunit of hemoglobin causes no anemia
1
- αα | α\
__ (#) gene(s) deletion of alpha subunit of hemoglobin causes mild anemia
2
- αα | \ (cis)
- α\ | α\ (trans)