Coagulation Screen

Дата канвертавання19.04.2016
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Coagulation Screen


SP Notes

Data Interpretation – Venkatesh

-> = causes of abnormalities

Prothrombin Time
- thromboplastin added

- tests the extrinsic pathway

- ratio compared to control (INR)

- tests factors: I, II, V, VII, X

-> warfarin

-> vitamin K deficiency

-> liver disease

-> DIC

-> artefact: incorrect sampling or increased haematocrit (> 55%)

Activated Partial Thromboplastin Time
- kaolin added

- tests intrinsic pathway

- tests factors: I, II, V, VIII, IX, XI, XII
-> heparin

-> DIC

-> haemophilia

-> liver disease

Thrombin Time
- thrombin added to undiluted plasma

- tests the conversion of fibrinogen -> fibrin

- prolonged in:
-> heparin

-> DIC

-> hypofibrinogenaemia

-> fibrin degradation products

- normal: 1.5-4.0

- high in: acute phase response

- low in:
-> sepsis

-> DIC

Fibrin Degradation Products (FDP’s)
- marker of fibrin and fibrinogen breakdown

- mixing of patients sample with pooled normal plasma – 50:50 mix

- failure to correct after mixing:

-> lupus anticoagulant present (should go on to autoantibodies and anti-cardiolipin antibodies)

Echis Time
- snake venom from Echis multisquamatus added to sample

- differentiates liver dysfunction from vitamin deficiency

- this activates prothrombin without requiring vitamin K

- is normal in vitamin K deficiency or warfarin use

- if prolonged:
-> factor deficiency (liver disease)

Retiplase Time
- used to detect deficiency or abnormalities in fibrinogen

- snake venom that has similar action to thrombin but is resistant to inhibition by antithrombin III

- interpret with TCT

- if retiplase time normal and TCT prolonged:

-> heparin

-> hirudin

-> direct thrombin inhibitors

Euglobin Lysis Time
- shortened time:
-> prescence of systemic fibrinolytic pathway activators

Urea solubility Test
- factor 13 stabilises fibrin

- if deficient 5M urea will dissolve it

Jeremy Fernando (2010)

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