IHL I - Bilirubin Metabolism and Platelet Function Flashcards
activity of aspirin?
inhibits platalet activity
through COX pathway (prostaglandins)
petechiae
pinpoint hemorrhages under skin
subQ bleeds
aspirin action of COX?
irreversible inhibition
due to acetylation of the enzyme
COX activity?
catalyzes production of TXA2 in arachidonic acid pathway
TXA2 and ADP promote platelet recruitment and aggregation to form platelet plug
TXA2
potent vasoconstrictor
abciximab
inhibit the GPIIb/IIIa receptors on platelets
no platelet aggregation
daibigatan
inhibits thrombin
therapeutic use of aspirin
antiplatelet therapy
cardiovascular disease, angine, CAD, post-MI
aspirin long term affects?
can develop a resistance to aspirin after a long time
variable among patients
PTT
pro thromboplastin time
measures the intrinsic pathways
Vit K requiring factors
2, 7, 9, 10
**liver disease - vit K goes down
platelet function assays
can measure protein activity
ristocetin cofactor assay
measure vWF activity
**ristocetin is an antibiotic leading to thrombocytopenia
induces platelet agglutination but only in the presence of vWF
platelet aggregometry
checks for aggregation of platelets
-if they aggregate, they are functioning correctly
shine a light through sample
-if light visible through test tube you can identify aggregation
hemophilia A
factor VIII deficiency
hemophilia B
factor IX deficiency
vWF deficiency
cant form platelet plug
also a decrease in factor VIII
type O blood type and vWF?
have lowest levels
AB has highest
purpura
subQ bleeding
treatment of vWF
dDAVP (desmopressin nasal spray)
type I vWD treatment
stimulates release of endogenous vWF from endothelial cells
also for hemophilia A (bc vWF activates factor VIII)
less at risk from thrombosis if vWF disease?
maybe
normal range of bilirubin?
< 2 mg/dL
source of bilirubin?
senescent RBCs broken down (120 days)
main site of RBC breakdown?
occurs extravascularly
in the spleen
heme oxygenase
breaks down heme to biliverdin
produces O2 and ferric iron (Fe3+)
requires NADPH
conjugated bilirubin formation?
enzyme: UDP-GT
adds glucuronic acid (or xylose or ribose)
stercobilin
oxidized from stercobilinogen in the large intestine
*presence of O2
crigler najjar
deficient UDP-GT
increased levels of indirect bilirubin (very high)
death early age
prehepatic jaundice
because of excess production of bilirubin following hemolysis
excess RBC lysis
Rh-ABO incompatibility
sickle cell disease
intrahepatic jaundice
impaired uptake, conjugation, or secretion of bilirubin
reflects a generalized liver dysfunction
congenital: Gilbert’s, Crigler-Najjar, Dubin-Johnson, Rotor
Posthepatic jaundice
obstruction of biliary tree
cholestasis
intrahepatic cholestasis
failure of excretion at the cellular level
-due to swelling of hepatocytes and edema
extrahepatic cholestasis
due to obstruction at any point in tract distal to the bile canaliculi
plasma bilirubin is conjugated
also pale-colored stool and dark urine
autoimmune disease of prehepatic jaundice?
Rho incompatibility
intrahepatic congenital diseases?
gilbert, crigler-najjar, dubin-johnson, rotor
posthepatic jaundice?
extrahepatic bile duct blockage
ex/ gall stones
direct coombs test
for incompatibility of blood tests
positive shows presence of antibody on blood cells
phototherapy treatment?
converts trans to cis isomer
makes it more water soluble
amylase and lipase
from the pancreas
elevated if problem in the pancreas
