Coagulation Lab Tests

Front 1

Purpose of Bleeding Time

Back 1

Screen for defects of PRIMARY hemostasis. Measures in vivo plt function

Front 2

Normal range for BT

Back 2

1-9 Minutes

Front 3

Causes of FALSELY increased BT

Back 3

aspirin
other drugs that inhibit plt fctn

Front 4

Conditions assoc with increased BT

Back 4

Thrombocytopenia, Platelet dysfunction, vascular abnormalities, vWF disease, Bernard-Soulier,
Glanzmann's thrombasthenia, Congenital storage pool disease, Afibrinogenemia, Ehlers-Danlos syndrome, Uremia

Front 5

Principle of Platelet Function Analysis

Back 5

Test cartriges w/ membranes coated w/ platelet agonists
-whole blood aspirated under controlled flow cond thru an aperture in membrane
-Plts undergo AAA on membrane surrounding aperture
-time req for plt plug to occulude aperture indicates plt function

Front 6

Purpose of Platelet Function Analysis

Back 6

Reliable, cost-effective
-easier than plt aggregometry

Front 7

Principle of Platelet Aggregation

Back 7

-PRP measured photometrically
-aggreg agent added, plts clump, % transmittance directly prop to amt clumping in plts
-Aggreg. agents: ADP, collagen, ristocetin, epinep., arachidonic acid

Front 8

What are the primary and secondary waves in the platelet aggregation test?

Back 8

1=direct response of plts to aggregating reagent (shape change)
2=complete aggregation (endogenous ADP release from plt dense bodies)

Front 9

What's special about using ristocetin in platelet aggregometry?

Back 9

it's action is dependent on interaction of vWF & GPIb/IX. Represents plt agglutination, not aggregation

Front 10

Purpose of PT Test

Back 10

-mainly monitor oral anticoag therapy
-screen for inherited EXTRINSIC or COMMON pathway deficiencies
-acquired factor deficiencies

Front 11

Principle of PT Test

Back 11

-Plasma re-Ca in presence of excess tissue factor & time for clot formation is measured
-Test bypasses intrinsic factors
-unaffected by plts (because FIII has phospholipids)

Front 12

What is the normal range for PT test? and what caveat is there?

Back 12

~10-14 sec
varies from lab to lab because of different techs, reagents, populations, equipment...

Front 13

Causes for elevated PT

Back 13

oral anticoag therapy
vitamin K deficiency
Liver disease (acquired cond)
specific coag factor deficiencies
inhibitor

Front 14

Purpose of APTT

Back 14

-screen to eval factors in INTRINSIC pathway (eval all xcpt VII,XIII,PF3)
-acquired or inherited
-monitor heparin therapy
-detect inhibitors in blood

Front 15

Principle of APTT

Back 15

-Ca in blood bound by NaCitrate to prevent coag
-plasma after centrifg contains all intrinsic factors xcpt Ca & plts
-must add: Ca source (CaCl), Phospholipid substitute (PF3), activator (ellagic acid)

Front 16

normal ranges for APTT

Back 16

- 30-40 sec
-varies lab to lab

Front 17

APTT increased in...

Back 17

INTRINSIC or COMMON pathway deficiencies
heparin therapy (main use)
inhibitors

Front 18

What does elevated APTT w/ prolonged incubation mean?

Back 18

Fletcher factor deficiency

-incubating 10 min instead of 4

Front 19

Purpose & Principle of TT

Back 19

measures conversion of fibrinogen to fibrin after adding excess thrombin to citrated plasma
-time for clot to form measured

Front 20

Normal range for TT

Back 20

10-15 sec

Front 21

Causes of prolonged TT

Back 21

Hypofibrinogenemia
Dysfibrinogenemia
Paraproteins (e.g., cryoglobulin)
Presence of heparin
Presence of FDPs
Presence of plasmin

Front 22

Principle of Quantitative Fibrinogen

Back 22

ability of thrombin to convert fibrinogen to fibrn
-clotting time of diluted plasma INVERSELY prop to fibrinogen conc
-excess amts thrombin added to diluted plasma & clotting time noted

Front 23

Normal range for Quant Fibrinogen

Back 23

200-400 mg/dL

Front 24

Causes of LOW fibrinogen levels

Back 24

<200 in children normal!
-hypofibrinogenemia, dysfibrinogenemia
-liver disease
-DIC
-fibrinolysis

Front 25

Causes of HIGH fibrinogen levels

Back 25

Remember: Fibrinogen=Acute Phase Reactant
-Pregnancy
-Trauma
-estrogen therapy

Front 26

Purpose of FXIII screening test

Back 26

Remember: FXIII changes H-bonds to covalent in clot
-deficiency of FXIII results in unstable clots
-test is time for clot to dissolve in 5M urea. Normal=~24 hrs

Front 27

Principle of FDP

Back 27

-latex particles coated w/ Ab to fibrinogen fragments D & E
-positive is agglutination

Front 28

Purpose of soybean trypsin inhibitor in FDP

Back 28

prevents In vitro fibrinolysis

Front 29

Normal range for FDP

Back 29

10-40 ug/dL

Front 30

Purpose of D-Dimer

Back 30

-latex agglut for specific cross-linked fibrin derivatives w/ D-Dimer domain
-eval pts w/ DVT or PE (which have elevated values)

Front 31

Purpose of mixing studies

Back 31

differentiate a factor deficiency from the presence of an inhibitor.
Mix pt. plasma w/ normal plasma. If inhibitor, will also inhibit normal factors, thus no correction

Front 32

What are 2 specific coagulating inhibitors, and what would the results be in mixing studies?

Back 32

Lupus-like anticoagulant,
Factor VIII inhibitor

-There will be NO CORRECTION after 2 hr incubation
(FVIII inhibitor corrects after immediate, but goes away)

Front 33

What is the dRVVT

Back 33

Dilute Russell's Viper Venom Time
-has venom, Ca, LIMITED conc phospholipid
-venom in presence of FV, phospholipid, and Ca will activate FX => prothrmbn to thrombin
-dRVVT ELEVATED w/ lupus anticoagulant

Front 34

What patients do we see inhibitors?

Back 34

Chronic illness
FVIII and FIX deficiencies
congenital coag deficiencies
postpartum women