Bleeding DIsorders Flashcards
In general, how do the clinical features of platalet bleeding and factor bleeding differ?
platelet: superficial bleeding (petechiae), spontaneous
factor: deep (joints), big bleeds, usually trauma
What is the most common hereditary bleeding disorder?
von willebrand disease
What’s the inheritance pattern for vWD?
autosomal dominant
Why does vWD vary in severity
because there are three types: one you just have decreased vWF, one you have abnormal vWF and the last one ou have no vWF
What cells make vWF>
megakaryocytes and endothelial cells
What does vWF do?
it esstneially glues platelets to subendothelium - gets the first layer of the clot on
WHat factor is carried by vWF so it doesn’t degrade?
factor VIII
What sort of bleeding will patient with vWD present with?
mucosal bleeding: nose bleeds, heavy menses, bruising, excessive bleeding after dental extractions
Why can you also get deep joint bleeding in really severe cases of vWD?
because it leads to a secondary factor 8 deficiency
What will the following lab tests show in vWD?
bleeding time? PTT? INR?
bleedint time prolonged PTT prolonged (corrects with mixing study) INR normal because it measure the extrinsic pathway only
If you do a platelet aggregation study, with what reagenet will you see it’s abnormal for vWD?
with ristocetin, which makes your platelets express GP Ib
It should make your platelets aggregate unless you odn’t have the vWF for the GPib to bind to
What’s the treatment for vWD?
DDAVP - which raises VIII and vWF levels if you have the tye where it’s just decreased
Cryoprecipitate (which containes VIII and vWF) if you don’t have any or you rhave abnormal
Facotr VIII - but avoid that whenever possible because patient can make antibodies to it eventually
What’s the most common FACTOR deficiency?
hemophilia A
WHat’s the interitance pattenr for the hemophilias?
x-linked recessive (so most cases are in boys, women are carriers)
How many cases of hemophilias are from raondom mutations?
30%
What factor is decreased in hemophilia A?
factor VIII
What sort of bleeding will hemophilia A patients present with?
deep joint bleeding that can be disfiguring over time
prolonged bleeding after dental work
rarely, mucosal hemorrhage (can be fatal)
What will the following labs show in Hemophilia A:
INR? TT? platelet count? bleeding time? PTT?
INR normal
TT normal
platelet count normal
bleeding time normal (remembe rit only looks at platelets)
PTT prolonged (corrects with mixing study)
What’s the treatment for hemophiliaA?
DDAVP - can increase VIII
Factor VIII - only when absolutely necessary
What factor is decreased in hemophilia B?
factor IX
Which is more common: a or b?
A is much more common (but still super rare)
What hereitary platelet disorder stems from abnormal GP Ib?
Bernard Soulier Syndrome
What do the platelets look like in bernard soulier syndrome?
just huge - like RBC huge
So is bernard soulier an issue with adhesion or aggregation?
adhesion
what hereditary platelet disorder arises from a lack of GP IIa-IIIb?
Glanzmann Thrombasthenia
Is glanzmann thrombasthenia an issue with adhesion or aggregation
adhesion is fine, aggregation is what’s lacking
What hereditary platelet disorder arises from a lack of apha granula?
gray platelet syndrome (mild bleeding)
What syndrome is a lack of delta granules associated with>
Chediak-Higashi
In general, what happens in disseminated intravascular coagulation?
Sometimes triggers coagulation, causing thrombosis
the platelets and factors all get used up by that coagulation, so you eventually get bleeding
What sort of anemia do you get with DIC?
microangiopathic hemolytic anemia as RBCs try to get around the thrombi
What are the four MOST common causes of DIC?
malignancy
OB complications
sepsis
trauma
(others include adenocarcinoma, mis-treated acute promyelocytic leukemia, burns and vasculitis)
What are the symptoms of DIC?
Either insidious or fulminant:
multi-system disease with thrombosis and or bleeding everywhere
What will the following labs do in DIC?
INR, PTT, TT, FDPs, fibrinogen?
INR, PTT and TT all prolonged (because you have no factors) FDPs increased (because you're tyring to break the clots down) FIbinrogen: decreased (because you used it all)
What’s the treatment for DIC?
treat the underlying disorder
support with blood products
What disease is caused by antiplatelet antibodies?
idiopathic thrombocytopenic purpura
Why is ITP a diagnosis of exclusion
because it’s rare and because we don’t have a good lab to look for the antibodies
Specifically, what are the antibodies attacking on the paltelets?
either GPIb or GP IIb-IIIa
What eventually kills the platelets in ITP?
splenic macorphages- after the antibodies opsonize it
What are the two kinds of ITP?
acute and chronic
Who gets chronic ITP? How doe sit present?
Adult women
Presents with nosebleeds, easy bruising
hard to treat
Who gets acute ITP? How?
children - usually after viral illness
usually self limiting, but can become chronic
What will the following lab tests do in ITP? INR? PTT? What will you see on histology?
INR and PTT will both be normal, because it’s no a coaculation issue, it’s a platelet issue
On histology you’ll see thrombocytopenia (low platelets), normal or increased megakaryocytes and the platelets that are there will be big because the megakaryocytes are trying to crank them out fast
What are the treatments for ITP?
glucocorticoids (most people respond to this)
splenectomy
intravenous immunoglobulin
What are the two thrombotic microangiopathies we learned about?
thrombotic thrombocytopenic purpura (TTP)
Hemolytic Uremic Syndrome (HUS)
What characteristics do all the thrombotic microangiopathies have in common?
all have thrombi, thrombocytopenia and microangiopathic hemolytic anemias
Basically, in TTP and HUS< something triggers activation of what? So how are they different from DIC?
platelets, leading to thrombi
DIC gets thrombi too, but that’s an issue with the coagulation cascade, not the platelets
Lack of what enzyme leads to TTP?
ADAMTS13
What does ADAMTS13 do?
new vWF is unusually large, and unusually large vWF cause splatelet aggregation
ADAMTS13 cleaves the large vWF into little vWF, which is less active and won’t cause uncontroled platelet aggregation
What are the clinical findings in TTP?
hematuria, jaundice (From the MAHA) bleeding and bruising (brom thrombocytopenia) fever bizarre behavior (clots in brian) renal faiure (from clots in kidneys)
What’s the treatment of ACQUIRED TPP? hereditary?
acquired - plasmapheresis
hereditary - plasma infusions
What infection is associated with hemolutic uremic syndrome?
E.coli
specifically the O157:H7 strain, which mains a paritcualrly nasty toxin that injures endothelial cells
Non-epidemic HUS comes from a defect in what?
complement factor H - somehow activates platelets
Which group of people are most susceptible to the epidemic form?
children and elderly
What are the clinical findings of the epidemic form?
bloody diarrhea and then renal failure
fatal in 5%
What are the clinical findings in the non-epidemic form of HUS?
renal failure
relapsing-remitting course
fatal in 50% of cases
What’s used for treatment in HUS? What DON”T you use for treatment in HUS?
supportive care and dialysis
NOT antibiotics because it can increase toxin release
