S18C227 - Tests of Hemostasis Flashcards
1
Q
Site of bleeding gives indication of bleeding diathesis
A
- mucocutaneous, petechiae, ecchymoses, epsitaxis, GI/GU bleed or heavy perids is characteristic of a platelet d/o
- purpura with thrombocytopenia indicates systemic illness
- bleeding into joint and potential spaces and delayed bleeding is common with coagulation factor deficiencies
- pts with both mucocutaneous and bleeding in deep apces may have DIC (platelet and coag factor abnormality)
2
Q
Thrombus
A
- DVT/PE
- possibly underlying hypercoagulable state
- acquired hypercoagulable d/o and inherited
3
Q
acquired hypercoagulable d/o
A
thrombocythemia polycythemia vera paroxysmal nocturnal hemoglobinuria antiphospholipid syndrome cancer
-can have both arterial and venous thrombi
4
Q
inherited hypercoagulable d/o
A
- Factor V leiden
- prothrombin mutations
- hyperhomocysteinemia
- protein C and S deficiencies
- antithrombin
-tend to be just venous thrombi
5
Q
normal coagulation formation
A
- platelet plug forms (primary hemostasis)
- then a cross-link of fibrin is produced over top to strengthen the plug (secondary hemostasis)
- these rxns are counterregulated by the fibrinolytic system to limit the fibrin clot and prevent excessive clot formation
6
Q
Primary Hemostasis
A
- formation of platelet plug requires:
- normal collagen
- normal platelets
- normal von WF (connects platelets to endothelium via glycoprotein Ib)
- normal fibrinogen (connects platelets to each other via glycoprotein IIb and IIIa)
- occurs in 20sec
7
Q
Tests of primary hemostasis:
A
-platelet count: 150-300 is normal
in thrombocytopenia bleeding not a problem until platelets
8
Q
Secondary hemostasis tests: PT and INR
A
PT and INR
- PT 11-13s
- INR 1
- extrinsic clotting pathway factors VII, X, V, prothrombin and fibrinogen
- prolonged PT: warfarin (inhibition of 1972 vit K dependent factors), liver dz (decr factors), Abx that inhibit vit K factors (cefotaxime)
9
Q
Secondary hemostasis tests: aPTT
A
aPTT: 22-34s
- activated partial thromboplastin time
- intrinsic system
- factors XII, XI, IX, VIII, X, V, prothrombin, and fibrinogen
- prolonged if: heparin, factor deficiencies (factors have to be
10
Q
Secondary hemostasis tests: fibrinogen level
A
- 1 – 11.8 μmol/L
- low in DIC
- elevated as an acute phase reactant
11
Q
Secondary hemostasis test: mix testing
A
- performed when an there is an abnormal result on screening test
- pts plasma is mixed with normal plasma and screening is repeated
- if mixing corrects the screening test then one or more factors are deficient
- if mixing does not correct the test then there is an inhibitor present
12
Q
Hemostatic tests: FDP
A
Fibrinogen degradation products
-
13
Q
Hemostatic test: D-dimer
A
14
Q
Hemostatic test: factor V leiden
A
- looks for activated protein C resistance and confirmatory test analyzes DNA sequence of Factor V gene
- screening assay uses aPTT with and w/o added activated protein C
- mutation associated with thromboembolism in people
15
Q
Hemostatic test: antithrombin
A
- 30-45mg/dL
- measures level of antithrombin
- not vit K dependent
- pts with deficiency require higher doses of heparin for anticoagulation therapy
- deficiency causes thromboembolism in
