RBC II Putthoff, Bleeding Disorders Flashcards
excessive bleeding can result from what
increased fragility of vessels, platelet deficiency or dysfunction and derangement of coagulation
PT time asses what
extrinsic and common coagulation pathways
what can cause increased PT time
dysfunction factor V VII X prothrombine or fibrinogen
What does PTT assess
intrinsic and common clotting pathways
prolonged PTT indicates what
deficiency in : V VII IX X XI or XII, prothrombin or finbrinogen
bleeding due to vessel wall abnormalities are characterized how clnicallys
small hemorrhages (petichiae and purpura)
What are PT and PTT times in vessel wall abrnomality bleeding disorders
normal
what infections can cause petechial and purpuric hemorrhages
meningococcemia, infective endocarditis and some of the rickettsial
How do drugs induce cutaneous petechiae and purpura
vascular injury from drug induced IC in vessel walls which leads to HS vasculitis
Scurvy and Ehlers-Danlos syndrome and Cushings are assoc with what type bleeding disorder
microvascular bleeding that results from collagen defects that weaken vessel walls
What is Henoch Schonlein purpura
systemic immune disorder of unknown cause characterized by purpuric rash, colicky abdominal pain, polyarthralgia and acute glomerulonephritis
what Ig is assoc with henoch schonlein
IgA
What is weber-osler rendu syndrome
hereditary hemorrhagic telangiectasia
dilted tortuous blood vessels with thin walls that bleed readily
what type of hereditary pattern is seen in hereditary hemorrhagic telangiectasia
autosomal domintant
mutations in TBF bet signaling
where are the common sits of bleeding in hereditary hemorrhagic telangiectasia
nose, tongue, mouth, eyes and GI tract
Perivascular amyloidosis weakening of blood vessels walls is a complication seen in what disorder
amyliod light chain amyloidosis
platelet numbers are how low to be considered associated with nontraumatic bleeding
<20,000
what will PT and PTT be in bleeding from thrombocytopenia
normal
where are common hemorrhage sites for bleeding from thrombocytopenia
skin and mucous membranes of GI and gU tracts
what is most feared thromcytopenic bleeding site
intracranial
4 main causes of thromcoytopenia
decreased platelet production
decreased platelet survivial
sequestration
dilution
decreased platelet productiosn generally occurs when
depressed arrow output like in anemias and leukemias
drugs or alcohol that can supress production
HIV
myelodysplastic syndromes
What is immune thrombocytopenia
destruction caused by the deposition of Ab or IC on platelets
What are Ab that recognized self Ag
autoAb
what are Ab that recognize non-self Ag
alloAb
When can alloAb arise
when platelets are transfused
cross placenta durign pregnancy
Most important non immunoe causes of decreased platelet survival are what
DIC, thrombotic microangiopathies
mechanical injury
how much of platelets can spleen sequester
80-90%
what is dilutional thrombocytopenia
massive transfusions can produce a dilutional thrombocytopenia
What causes chronic ITP
autoAb mediated destruction of platelets
What conditions can lead to secondary chronic ITP
SLE, HIV, B cell neoplasms like CLL
autoAb are usually against what in chronic ITP
membrane glycoproteins IIb-IIIa or Ib-IX
IgG
What is a good Tx for chornic ITP
splenectomy because thats where the opsonized platelets from autoAb are remobed
is there splenomegaly in chronic ITP?
no
what does BM look like in chronic ITP
increased # megakaryocytes
what will PS look like in chronic IT
abnormally large platelets
sign of thrombopoiesis
population affected by chronic ITP
adult women younger than 40 y.o
3:1 F:M
clinical signs ITP
insidious onset, bleeding into the skin and mucosal surfaces
pinpoint hemorrhages that can lead to ecchymoses
Hx easy bruisning and nosebleeds
melena, hematuria or excessive menstural dlow
fatal complications of chronic ITP
subarachnoid hemorrhage and intracerebral hemorrhage
PT and PTT in chronic ITP
normal
What causes acute ITP
autoAb to platelets
When does acute ITP occur
childhood disease 1- 2 weeks post viral illness
Tx for acute ITP if severe
glucocorticoids
Which cases of acute ITP are mroe severe
without viral prodrome the thrombocytopenia persists and usually progress to chronic ITP
What drugs most commonly assoc with inducing thrombocytopenia
quinine, quinidine, vancomycin by binding platelet glycoptoeins and creating antigenic determinants
how do platelet inhibitory drugs lead to thrombocytopenia
induce conformational changes in glycoprotein IIb IIIa and create immunogenic epitope
What is type I Heparin induced thrombocytopenia
rapidly after onset of therapy,
from direct platelet aggregating effect of heparin
What is type II HIT
5-14 days post Tx and usually leads to life threatening venous and arterial thrombosis
What cuases HIT type II
Ab recognize heparin complexes and paltelet factor 4 so when they bind activates platelets and thrombosis
How does HIV lead to thrombocytopenia
impaired platelet production and increased destruction
development of auto Ab in B cell hyperplasia
Thrombotic microangiopathy includes what
many syndromes
TTP HUS
what are thrombotic microangiopathies
insult that lead to activation of platelets that deposit as thrombi in small blood vessels
What is the pentad of TTP
fever, thrombocytopenia, microangiopathic hemolytic anemia, transient neurologic deficits and renal failure.
how is HUS distinguished from TTP
absence of nuerologic Sx and has acute renal failure
frequent in children
Intravascular thrombi in TTP and HUS lead to what
microangiopathic hemolytic anemia with widespread organ dysgunction and thrombocytopenia
why are TTP and HUS different than DIC
actication of coagulation cascade not primary importance
normal PT and PTT
what mutation is assoc with TTP
deficiency of ADAMTS13
what is Typical HUS
E coli strain O157:H7 infection
what is atypical HUS
alternative Cā pathway inhibitor deficiencies like factor H, membrane cofactor protein CD46 or facor I
