Feb 27, Clotting, Immunohematology Flashcards
Platelet growth factor?
Thrombopoietin
Three phases in coagulation of an acute injury:
Adhesion, Activation, Aggregation
What binds both platelets and factor VIII in acute injury?
VWF
What molecule does VWF actually grab onto?
Glycoprotein 1B
What does ADP and Ca2+ signalling do within the platelet?
Signals for more activation, release of granules, serotonin
What does aspirin inhibit?
Arachadonic acid
Arachadonic acid acitivates ________ which activats _____, which induces platelet synthesis/release
Prostaglandin H2 (PGH2), Thromboxane (TXA2)
Which three molecules actually build the fibrinogen meshwork?
VWF, Platelets, and Fibrin
What is the mechanical cause of EDTA Pseudothrombocytopenia?
Clumping of poorly-made platelets. (CBC machine counts clumps as RBC’s)
One disorder you should always keep in mind for pancytopenia/thrombocytopenia?
MDS
Toxic Granulation
decreased PLT ct, with pinkish WBC cytoplasm, indicates a bacterial or viral infection
Immune Thrombocytopenia Post-Infection
Change in immune system leading to low PLT ct. (HIV, HepC, chronic EtOH use)
What do you see on smear with chronic EtOH abuse?
decreased PLTs, acanthrocytes, target cells (will also see internal bleeds ex. esophageal varices)
Immune Thrombocytopenia Purpura (ITP)
Body makes Ab to PLTs. Pt has easy bleeds/bruising with a decrease in PLTS only - no other WBC disorders
How to treat Immune Thrombocytopenia Purpura (ITP)?
Splenecomy, steroids, rituximab, IV IgG
VonWillebrand Disease/Disorder
No attachment of Factor VIII to VWF - leads to severe bleeds
Three types of VonWillebrand Disease/Disorder:
I: not enough VWF
II: VWF doesn’t fxn properly
III: no VWF at all
What does DDAVP do?
Increases the functionality of existing VWF
Tx for type I VW disease
How do you treat type II or III VW disease?
Factor VIII replacement therapy
Heparin artificially prolongs PTT or PT?
PTT
DDx for a long PTT?
x-linked hemophilia, heparin OD, Factor XI deficiency, VW disease, excess fibrinogen
DDx if PT is more prolonged that PTT?
Liver disease, vit K deficiency, Warfarin OD, factor VII hemophilia
DDx if PTT is more prolonged than PT?
DIC! sepsis!
How does mixing Pt plasma and donor plasma detect inhibitors causing thrombosis?
The mixture will not correct the thrombosis
What is the Pt prone to with Antiphospholipid Syndrome?
Both venous and arterial thromboses (liver disease, migranes)
How do you confirm a Lupus Anticoagulant?
With RVVT the Russel Viper Venom Test - it activates Factor X
What enzyme adds an A or B allele sugar onto RBC antigens?
Glycosyl transferase
What does the RHD gene do?
Makes Rh factor (D/d)
What is Hemolytic Disease of the Newborn?
When a Rh(-) mom has a Rh(+) firstborn, immunizing her against another Rh(+) baby. Will kill the second fetus
What is given to pregnant mothers to disallow Hemolytic Disease of the Newborn?
Rhogam! (IgG Ab to Rh(+) from male volunteer donors)
What is deficient in Bombay Blood types? What blood type are these Pt’s usually accidentally categorized with?
Glycosyl transferase - usually test as blood type O with questionable lab results
What happens if you give a patient the wrong blood type in transfusion?
Intravascular RBC lysis, causing crystals to form in the glomerulus, leading to acute renal failure
What do the Coombs tests actually test for?
Antiglobulins (Autoimmune)
Direct Coombs procedure?
Take washed RBCs from suspect Pt, add the coombs Ab since it will bridge the Pt’s IgG’s that are attached to RBC’s - causes agglutination if +
Indirect Coombs procedure?
Add susptect Pt’s serum to donor RBCs with needed antigen (ex: Rh- Pt serum with Rh+ RBC’s), add coombs Ab to see if it agglutinates
What does a + Direct Coombs test imply?
The + agglutination implies that there is an AUTOIMMUNE Ab issue
What Ab is present on RBC’s to detect different blood types? Why this kind of Ab?
IgM - since the A, B, O sugars are indeed carbohydrates that require the branching IgM Ab for detection
What does heparin do?
It induces AT3 action - increases natural anti-coagulation
What does Warfarin do?
It inhibits vit K oxyreductase, disallowing the recycling of vit K to II, VII, IX, XI
What is AT3?
A serine protease inhibitor that deactivates Factors X and IIa
How many saccharides are needed at least to inhibit Factor IIa with AT3? Factor X?
18 saccharides - IIa
15 saccharides - X
Would you give a pregnant woman Heparin or Warfarin?
Heparin
Which acts faster, heparin or warfarin?
Heparin
What do you give if a Pt OD’s on Heparin?
Protamine Sulfate (neutralizes the + charge of heparin)
Which medical issues indicate a need for daily Warfarin use?
PMH of stroke, DVT, recurrent MI’s, etc.
Besides warfarin, what are some other noteworthy oral anticoagulant drugs?
Pradexa, Eliquis, Xarelto
What are some derivatives of heparin?
Lovenox (low m.w. heparin)
Fondaparinux (synthetic pentasaccharide heparin)
What do fibrinolytic agents do? When do you use them?
Lyses clots right after they form - activates tPA’s. Use only in emergency situations only
Example of a fibrinolytic agent?
Alteplase
What do anti-PLT drugs mechanically do?
Inhibit PLT production of TXA2 (ASA)
Block the ADP receptor needed to activate PLTs (Plavix/Clopidogril)
Block GPIIb/IIIa to stop fibrinogen cross-linking
Examples of anti-PLT drugs?
Aspirin, Clopidogril (Plavix)
Which two molecules are crucial for successful fibrinogen cross-linking?
GPIIb and GPIIIa
