Heme/Onc Flashcards
Why are neonates prone to bleeding if not given a shot of Vitamin K at birth?
Enteric bacteria synthesize Vitamin K, and neonates lack these bacteria at birth.
Hemophilia __ is most common in what Nationality?
C, Ashkenazi Jews (and it is often autosomal)
What is the mechanism of action of Heparin?
Activates antithrombin
What lab value changes with Heparin?
Increase in PTT
Does low molecular weight heparin increase PTT?
No
What is the antidote for heparin?
Protamine sulfate
What is the mechanism of action of Warfarin?
Inhibits synthesis of vitamin K-dependent coagulation factors (II, VII, IX, X, proteins C and S)
What are the vitamin K-dependent coagulation factors?
Factors II, VII, IX, X, proteins C and S
What lab value does Warfarin affect?
Increases PT (INR)
What is the mechanism of action of tPA (tissue plasminogen activator - alteplase)?
Aids in conversion of plasminogen to plasmin, which breaks down fibrin.
How do you reverse the effects of Warfarin?
Rapid reversal = fresh frozen plasma
Reversal = vitamin K
How does tPA affect lab values?
Increases PT and PTT
What is the mechanism of action for Factor Xa inhibitors (apiXAban, riveroroXAban)?
Directly inhibits factor Xa.
Do you monitor PT/PTT with Factor Xa inhibitors?
NO
Is there a reversal agent for Factor Xa inhibitors?
Not yet
What is the mechanism of action for LMWH (enoxaprin)?
Mainly inhibits factor Xa
What is the mechanism of action for direct thrombin inhibitors (dabigatran, argatroban)?
Directly inhibits factor II (thrombin)
What anticoagulants work on IIa (thrombin)?
Heparin
LMWH (dalteparin, enoxaparin)
Direct thrombin inhibitors (argatrovan, dabigatran)
Hemophilias are __ linked clotting factor deficiencies
X
What lab value does hemophilias affect?
PTT (PT and bleeding times are normal)
A = factor VIII B = factor IX C = factor XI
What are the treatment options for bleeding in hemophilia?
Severe = transfusion
Not severe desmopressin (DDAVP) because it releases factor VIII from endothelial cells
What is in cryoprecipitate?
Mainly Factor VIII, fibrinogen (more concentrated source than FFP)
Smaller concentrations of Factor XIII, vWF, and fibronectin
What is vWD?
Von Willebrand Disease
Defect or deficiency in vWF (used to adhere platelets to site of injury) with decreased levels of factor VIII (which is carried by vWF)
What is the most common inherited bleeding disorder?
vWD
What is more severe, hemophilia or vWD?
Hemophilia
How does vWD often present?
In childhood, with recurrent and prolonged mucosal bleeding (epistaxis, gums, teeth, menorrhagia, after dental procedures)
How does hemophilia often present?
A young boy with spontaneous hemorrhage into tissues and joints, leading to arthropathy and joint destruction.
What is diagnostic of vWD?
Decreased agglutination, seen on ristocetin cofactor assay.
Does ASA increase the risk of bleeding in patients with vWD?
Yes
How can bleeding be controlled in vWD?
DDAVP (in mild/mod type 1)
What is the most common cause of hereditary thromboembolic disease?
Factor V Leiden
HIT: formation of blood clots and __% drop in platelet count
50% (rapid)
What conditions is APS (antiphospolipid syndrome) often associated with?
SLE, rheumatoid arthritis
How can Protein C or S deficiency present?
Hypercoagulable state with skin or tissue necrosis following warfarin administration
A patient with rapid onset dyspnea, pleuritic chest pain, hypoxia, tachycardia, increased alveolar arterial oxygen gradient
PE
What is DIC characterized by?
Thrombosis + Hemorrhage
Aquired coagulopathy caused by deposition of fibrin in small blood vessels, leading to thrombosis and end-organ damage.
Depletion of clotting factors and platelets lead to bleeding diathesis.
How can you differentiate DIC from liver disease?
Factor VIII is depressed in DIC (normal in liver disease)
What are the three causes of microangiopathic hemolytic anemia?
- HUS
- TTP
- DIC
“DICk’s HoUSe got TTPed because he caused microangiopathic hemolytic anemia”
What is the most immunologic disorder in women of childbearing age?
Idiopathic Thrombocytopenic Purpura
What is the differential diagnosis of thrombocytopenia?
HIT SHOC
HIT or HUS ITP TTP or Treatment (meds) Splenomegaly Hereditary Other (malignancy) Chemotherapy
What is the treatment for ITP (idiopathic thrombocytopenic purpura)?
Platelet count > 30,000 no treatment
Platelet count < 30,000 corticosteroid or IVIG
Second line: Anti-D (Rh) immunoglobulin and rituximab … they act as “decoys” so that WBCs will recognize them instead of IgG on platelets
What are the causes of microcytic anemia?
TAILS
Thalassemia Anemia of chronic disease Iron deficiency Lead poisoning Sideroblastic anemia
What is the most common cause of acute renal failure in kids?
HUS (hemolytic uremic syndrome)
An elderly man with hypo chromic, microcytic anemia is asymptomatic. Diagnostic test?
Fecal occult blood test and sigmoidoscopy; suspect colorectal cancer
What are the precipitants of hemolytic crisis in patients with G6PD deficiency?
Sulfonamides, antimalarial drugs, favs beans.
What is the diagnostic test for hereditary spherocytosis?
Osmotic fragility test
Pure RBC aplasia
Diamond-Blackfan anemia
What anemia is associated with absent radii and thumbs, diffuse hyper pigmentation, cafe au lait spots, microcephaly, and pancytopenia?
Fanconi anemia