Heme - Lab Eval Of Hemostasis

Front 1

Difference between plasma and serum

Back 1

Plasma has all proteins and electrolytes (so this is what we do coag testing on)

Serum is the liquid after clotting--so is does not have coagulation factors, fibrinogen, etc.!!!

Front 2

Blue top tube

Back 2

COAGULATION TESTS

Citrate is the anticoagulant. Citrate binds Ca++ making it unavailable for coagulation reactions.

Blood is centrifuged to get the plasma, and calcium is added back.

Front 3

Red top tube

Back 3

Assay serum electrolytes, antibodies, other proteins.

Centrifuge to remove clot and cells.

Front 4

Purple top tube

Back 4

Cellular elements assayed in whole blood with EDTA as the anticoagulant.

Front 5

Spontaneous bleeding and thrombocytopenia - threshold platelet value

Back 5

Spont bleeding uncommon if platelet count is above 10k/microliter.

Remember that thrombycytopenia can be a marker of another disease (even if not causing bleeding)

Front 6

Pseudothrombocytopenia

Back 6

Always rule it out! It is when in the purple cap tubes, EDTA causes the platelets to clump.
Avoid this by looking at the smear or doing the test in a blue top tube.

Completely benign

Front 7

Smear - platelet counting rule of thumb

Back 7

For each 100X field, each platelet represents about 15,000 per microliter.

(so if you see 10, there are 150000 per microliter)

Front 8

Platelet function tests (3)

Back 8

Bleeding time

PFA-100

Platelet aggregation

Front 9

Bleeding time

Back 9

Time to stop bleeding after incision.

Assays the platelet/BV wall interaction!

This is a poor test (very operator dependent, poor sens and spec, not predictive of surg bleeding, performed at 40mM Hg)

Over 9 minutes - start to suspect something.

More platelets, less bleeding time.

Front 10

PFA-100

Back 10

In vitro bleeding time.
Measures time until platelets occlude an aperture in an agonist coated membrane.

ONLY ASSAYS PLATELET FUNCTION (bc BV wall isn'tthere)

A combined test of platelet adhesion and aggregation.

Mimics physiological cases of blood flow (high shear and flow)

On the membrane is collagen with epinephrine/ADP.

The device measures a change in pressure once occlusion occurs.

Closure time prolonged with aspirin (if CEPI used) or thrombocytopenia

Front 11

Platelet aggregation

Back 11

Measures platelet response to specific agonists.

Front 12

Bleeding time will be prolonged in...

Back 12

Platelet disorders (quant and qual)
vWFdisease
Hypofibrinogenemia
BV wall disorders.

Note - aspirin is probably the most common cause of prolonged bleeding.

Front 13

PFA-100 cartridges

Back 13

CEPI - sensitive to platelet dysunfction (and aspirin)
***Guiseppe Franco is v. sensitive to aspirin***

CADP - not sensitive to qualitative platelet disorders or aspirin. But sensitive to VWFdisease.

Front 14

Intrinsic coagulation cascade pathway

Back 14

12-->11-->9+8....

Front 15

Extrinisc coagulation cascade pathway

Back 15

TF+VIIa-->...

Front 16

Common pathway - where does it start?

Back 16

X-->Xa

Front 17

Prothrombin time

Back 17

Time to form a clot when citrated plasma is added to thromboplastin and calcium mixture.

Thromboplastin is TF + phospholipid

Will be prolonged in deficiencies in extrinsic and common pathways! (because VIIa is not given, and neither is X, V, II, I).

You must give a source of phospholipids because there are no platelets!

INR (international normalized ratio) is the measure you want. It standardizes prothrombin time across different thromboplatsin reagents. (so the actual PTT is useless).

INR is good for people being monitored long-term with different machines.

Front 18

activated Partial Thromboplastin Time (aPTT)

Back 18

Time required to forma clot when citrated plasma is added to phospholipid+calcium+a negatively charged surface.

So partial thromboplastin is phopholipid and calcium (no tissue factor)

Prolonged with deficiencies in the intrinsic and common pathways. So it tests factors XI, IX, VIIIl; and X, V, II.

There is no INR correlate.

Keep in mind the necc. in vitro factors

This (intrinsic) is the "contact pathway."

Front 19

aPTT - in vitro factors

Back 19

These are needed in vitro, but not in vivo: HMWK, pre-kallikrein, XII.
So if you have a prolonged aPTT and a deficiency only in one of those three, you will not have a problem in real life (bc those factors not needed in vivo).

Front 20

Prolonged PT - implications

Back 20

Deficiency in extrinsic pathway (i.e. factor VII)

Mild liver disease, early vit K def, early warfarin (bc it affects VII first), factor VII def/polymorph/inhibitor.

Front 21

Prolonged aPTT - implications

Back 21

Deficit in contact (intrinsic) pathway.

Hemostatis factor deficiency (e.g. Hemophilia A-VIII, B-IX, C-XI)

Non-hemostatic factor deficiency (HMWK, prekallikrein, XII)

VWFdisease (bc factor VIII is not being chaperoned)

Intrinsic pathway factor inhibitor

Heparin.

Front 22

Prolonged PT AND aPTT - implications

Back 22

Deficiency in common pathway or multiple coag factor deficiencies in both pathways

Severe liver disease

Consumptive coagulopathy

Hemodilution (e.g. massive transfusion)

Severe Vit K def

Therapeutic warfarin (inhibits factors II, VII, IX and X)

Hypofibrinogenemia or dysfibrinogenemia

Direct thrombin inhibitors.

Front 23

Mixing study

Back 23

Determines if prolongation of PT/aPTT is due to deficiency or inhibitor.

1:1 mix of pt plasma and normal pooled plasma.

If corrects - deficiency. If not - inhibitor is present.

Weird pattern - test will correct immediately but then prolong after incubation for an hour. This is common with Factor VIII inhibitors.

And then once you do this, you wanna test individual factors (coag factor assays).

Front 24

Thrombin clotting time

Back 24

Detect fibrinogen abnormalities

Exogenous thrombin added to plasma and clotting time measured in seconds.

Prolonged in hypofibrinogenemia
Dysfibrinogenemia
Heparin, thrombin inhibitors.

Front 25

D-Dimer

Back 25

Fibrinolytic breakdown product of cross-linked fibrin.

Not a specific test - elevated in acute thrombosis.

Also elevated in...
DIC, cancer, infection, inflamm, surgery.

Front 26

Reasons for quantitative platelet disorders

Back 26

Decreased number, increased destruction, sequestration in spleen, decreased production

Front 27

Thrombocytopenia

Back 27

<150000

Pts present with bruising, petechiae (breaks in BVs), mucosal bleeding (GI, oropharynx, epistaxis), menorrhagia.

Due to increased destruction, sequestration or decreased production.

Front 28

Thrombocytopenia due to increased consumption

Back 28

Autoimmune mediated
Medication mediated
Thrombocytopenic thrombotic purpura
DIC
HELLP syndrome in pregnancy (hemolysis, elevated liver enzymes, low platelets) - many similarities to TTP
Hemolytic uremic syndrome (overlap with TTP)
severe bleeding (platelets are consumed)
vWDisease, type 2B

Note - in these cases, BM is normal. there is just too much conumption. BM can increase platelet manufacturing by up to 10X.

Front 29

Thrombocytopenia due to increased consumption - autoimmune mediated

Back 29

Autoimmune mediated process - idiopathic thrombocytopenia
Autoantibody against platelet antigens. Common in HIV infection. In children, associated with viral infections.

Front 30

Thrombocytopenia due to increased consumption - medication mediated

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Medications (immune-mediated)
quinine (low platelets and bleeding)
heparin (low platelets, no bleeding. triggers a paradoxical hypercoagulable state)

Front 31

Thrombocytopenia due to increased consumption - Thrombocytopenic thrombotic purpura (TTP)

Back 31

Clotting disorder

Pentad - Microangiopathic hemolytic anemia, thrombocytopenia, fever, neuro changes, renal failure.

Failure of ADAMTS13 to cleave vWF. so the big multimers have antibodies attacking it and also nonimmune causes are medications or BM transplantation.

Leads to formation of platelet thrombi in small BVs. (they are so big that they clog the vessels)

Tx is plasma exchange and/or immunosuppression.

Front 32

Thrombocytopenia due to sequestration

Back 32

Splenomegaly (goes from holding 30% to up to 90%)

Common causes -
portal HTN due to hepatic cirrhosis or portal/hepatic vein thrombosis.
or myeloproliferative disorders (spleen enlarges to become site of hematopoeitic elements).

Front 33

Thrombocytopenia due to decreased production

Back 33

Primary bone marrow disorders (leukemia, aplastic anemia, myelodysplasia)
BM infiltration (cancer, Gaucher's disease-lipid accum due to lysosomal storage disorder)
Viral infections (Hepatitis, HIV are directly toxic to megakaryocytes)
Toxins (alcohol, radiation, chemo, medications)
Nutritional def - B12, folic acid
Hered disorders - often mistaken for immune thrombocytopenia - not common.

Front 34

Acquired platelet disorders

Back 34

Medications (most common - aspirin, NSAIDS, GPIIb/IIIa inhibitors, ADP rec inhibitors, SSRIs, herbal supplements (gingko, garlic, ginger, feverfew, fish oil)
Uremia (circ platelet toxin accumulates and good dialysis will improve platelet function)
Myeloproliferative, myelodysplastic disorders
Cardiopulmonary bypass

Front 35

Aspirin --> acq platelet disorders

Back 35

Irrev. acetylates cyclooxygenase --> inhib of thromboxane A2. (last 7-10 days)

Front 36

NSAID --> acq platelet disorders

Back 36

Rev inhib of cyclooxygenase pathway. Effects last until drug is cleared from blood (24-48hrs)

Front 37

Bernard-Soulier disease

Back 37

Hereditary qualitative platelet disorders

Defect in GPIb receptor.

Front 38

Glanzmann thrombocythemia

Back 38

Hereditary qualitative platelet disorders

Defect in GPiib/iiia receptor

Front 39

Gray platelet syndrome

Back 39

Hereditary qualitative platelet disorders

Storage pool disorder

Absent alpha granules

Front 40

Quebec platelet syndrome

Back 40

Hereditary qualitative platelet disorders

Storage pool disorder - increased uPA in alpha granules and granule contents degraded

Front 41

Delta granule disorders (2)

Back 41

Hereditary qualitative platelet disorders

Storage pool disorders - decreased ADP release
(Hermansky-Pudlak and Chediak-Higashi syndromes)

Front 42

Signal transduction disorders, secreation disorders

Back 42

Hereditary qualitative platelet disorders

Defects in transmitting signals from receptors to granules, resulting in decreased release of granule contents.

Front 43

Scott syndrome

Back 43

Hereditary qualitative platelet disorders

Defect in assembling coag factors on platelet surface.