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81 Cards in this Set

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Giant platelet syndrome
Defect – glycoprotein Ib/IX/V complex is missing


Heterozygotes – near normal platelets
Homozygous – moderate to severe bleeding, prolonged bleeding time, enlarged platelets, thrombocytopenia and decreased platelet survival, plt# 40,000/mcL to normal


Rare – autosomal recessive
Manifested in infancy
Defective platelet function ; ecchymoses, epistaxis and gingival bleeding


Aggregation studies – normal aggregation response to ADP, epinephrine, collagen and arachidonic acid
Do not respond to ristocetin and diminished response to thrombi
Lack of binding to VWF


Abnormality cannot be corrected by addition of human plasma or cryoprecipitate
Treatment of choice is platelet transfusions (apheresis platelets preffered to prevent alloantibodies), desmopressin acteate (DDAVP) and recombinant factor VIIa


Heterozygous are normal
Homozygous have serious bleeding problems
Seen in neonatal periods of life after circumcision
Clinical features – manifests as petechiae, purpura, menorrhagia, GI bleeding and hematuria


Abnormal or deficient in GP IIb/IIIa complex needed for binding fibrinogen, VWF, fibronectin
Leads to defect in hemostatic plug formation and serious bleeding


Blood smear feature-normal platelet count and morphology. Abnormal tests – bleeding time, in-vitro clot formation. Lack of aggregation with all platelet activating agents
Ristocetin-induced binding of VWF to platelets and platelet agglutination are normal

CBC is normal unless there is another underlying reason
Platelet factor 3 test is diminished because:
Fewer microvesicles
Complex GPIIb/IIIa missing for prothrombin
Not as activated by thrombin as normal platelets


Clinical features
Hemorrhage severe and disabling
Epistaxis, ecchymosis, hemarthrosis, subcutaneous hematoma, menorrhagia and GI and urinary tract hemorrhage


Single donor platelet apheresis products, HLA-matched donor platelets, or ABO matched donor platelets
Hormonal therapy to control menorrhagia
Antifibrinolytic therapy to control gingival hemorrhage
Recombinant factor VIIa


Mucocutaneous hemorrhage and hematuria, epistaxis and easy and spontaneous bleeding
Platelet count is normal
Bleeding time usually prolonged
Platelet aggregation abnormalities usuallly seen


Most common plt secretion disorder
Dense granule deficiencies
Alpha granule deficiencies

Storage pool release reaction diseases

Storage pool release reaction diseases

Thromboxane pathway disorders


Albinism, Nonalbinism. bleeding is mild limited to easy bruisability


Autosomal recessive
Tyrosinase positive oculocutaneous albinism
Mutations mapped to chromosome 19
Common abnormality in this disorder is marked dilation and tortuosity of surface-connecting tubular system (Swiss cheese platelet)

Hermansky-Pudlak syndrome

Rare autosomal recessive
Partial oculocutaneous albinism
Frequent pyogenic bacterial infection
Large lysosomal granules
Platelet δ-granule deficiency

Chédiak-Higashi syndrome

Hermansky-Pudlak syndrome, Chédiak-Higashi syndrome


X linked recessive disease characterized by triad of severe eczema, recurrent infections owing to immune deficiency and life threatening thrombocytopenia
Wiskott Aldrich Syndrome

Unable to make antipolysaccaride antibodies which results in propensity for pneumococcal sepsis
Found primarily in males
Milder form – hereditary X-linked thrombocytopenia

Wiskott Aldrich Syndrome

Gene codes for 502 amino-acid protein, WASP found exclusively in hematopoetic cells
Platelets are structurally abnormal
δ granules are decreased, platelets are small
Decreased aggregation response to ADP collagen and epinepherine

Wiskott Aldrich Syndrome

Rare autosomal recessive disorder
Congenital absence of radial bones
Numerous cardiac and skeletal disorders
Platelets have structural defect in δ granules with abnormal aggregation response

Thrombocytopenia with absent radii TAR

Alpha granules are storage sites for proteins produced by the megakaryocyte (e.g. platelet-derived growth factor, thrombospondin, and platelet factor 4) or present in plasma and taken up by the platelets and transported to α-granules for storage (e.g. albumin, immunoglobulin G(IgG), and fibrinogen)

Alpha granule deficiency: Gray Platelet Syndrome

absence of the α granules
autosomal recessive. lifelong bleeding mild bleeding tendencies, prolonged bleeding time, moderate thrombocytopenia, fibrosis of the marrow and large gray platelets on Wright stained film

Gray platelet disorder

Electron photomicrographs appear to have no α granules
Contain vacuoles and small α granule precursors that stain positive for VWF and fibrinogen
Plasma levels of PF4 and α thromboglobulin are increased
Early onset of myelofibrosis

alpha granule deficiency

Deficient α and δ granules
Autosomal dominant inheritance
Membrane abnormalities

Alpha-delta storage pool deficiency

Autosomal dominant disorder
Deficiency of multimerin and shows protease related degradation of many α-granule structure

Quebec platelet disorder

the pathway is required for mobilization of ionic calcium and initiation of events resulting in release in secretion and aggregation of platelets

Thromboxane Pathway mechanism

inhibits cyclooxygenase an enzyme required in the release of thromboxane A2

aspirin and ibuprofen

required for storage secretion and platelet aggregation in response to epinephrine, ADP and low concentration of collagen

Thromboxane A2

Clinical features – lifelong mild bleeding disorder
Laboratory features – lack aggregation response

Glycoprotein (GP) Ia/IIa integrin deficiency

Clinical features – mild bleeding
Laboratory features – failed adhesion with collagen

Glycoprotein VI (GPVI) deficiencies

Drugs that are Inhibitors of

prostaglandin pathway

Inhibitors of Membrane Function

Thienopyridine derivatives
Anti-GP IIb/IIIa agents, Dipyridamole
Antibiotics, Dextrans, Hydroxyethyl starch
Miscellaneous drugs

Cause of dysfunction coating of platelet membrane by paraprotein
Paraprotein interferes with fibrin polymerization
Complications of amyloidosis
Clinical features – significant bleeding

Multiple myeloma and Waldenström macroglobulinemia

Clinical and laboratory features –surgical bleeding after surgery, thrombocytopenia, severe platelet function defect

Cardiopulmonary bypass surgery

Reduction in clotting proteins, reduction of proteins in the natural anticoagulant pathways, dysfibrinogenemia and excessive fibrinolysis
Thombocythemia in association with hypersplenism and alcohol toxicity

Liver disease

Bleeding due to platelet dysfunction, concentration of guandinosuccinic acid is higher
causes prolonged bleeding time


Incidence seen in more than 150 families
Clinical features - platelets do not exhibit normal function
Laboratory features – prolonged bleeding time, platelet aggregation test results are abnormal, platelet function abnormality

Hereditary afibrinogenemia

Associated disorders – hyperlipidemia, diabettis mellitus, peripheral arterial occlusive disease, acute arterial occlusion, MI and stroke
Laboratory features – platelets aggregate at lower concentration of of aggregating agents
Spontaneous aggregation
Spontaneous pool disease – exhausted platelets

Hyperaggregable platelets

Autosomal dominant. Thin walled blood vessels w/ discontinuous endothelium, inadequate smooth muscle and discontinuous endothelium, inadequate elastin. Telangiectasis – dilated superficial blood vessels that create small focal red lesions . Epistaxis, skin and mucous lesions, Bleeding time normal

Rendu-Weber-Osler syndrome (Hereditary Hemorrhagic Telangiectasia

Giant cavernous hemangioma (vascular tumor)
Bleeding diathesis
Acute or Chronic DIC, intravascular coagulation and microangiopathic hemolytic anemia

Hemangioma-Thrombocytopenia (Kasabach-Merritt) syndrome

autosomal dominant, recessive or X-linked
Hyperextensible skin, hypermobile joints
Positive tourniquet and prolonged bleeding

Ehlers-Danlos syndrome

anaphylactoid purpura is allergic manifestations (skin rash and edema) when accompanied by transient arthralagia, nephritis, abdominal pain and purpuric skin lesions
Henoch-Schönlein purpura (Allergic Purpura)

Autoimmune disease – mediated by immune complexes that contain IgA
Clinical features – disease of children 3-7 years old
Laboratory features – platelet count is normal
WBC and ESR is elevated

Henoch-Schönlein purpura (Allergic Purpura)

platelet function inhibited by myeloma proteins.
Clinical features – cause severe hemorrhagic manifestations due to hyperviscosity and platelet dysfunction. abnormality in platelet aggregation, secretion, clot retraction, and procoagulant activity
Treatment – plasmapheresis and chemotherapy


the deposition of abnormal quantities of amyloid in tissues. Amyloid is fibrous protein consisting of rigid, linear, non-branching, aggregated fibrils
Clinical features – purpura, hemorrhage, thrombosis. abnormal platelet function and thrombocytopenia
Treatment – none effective


more common in elderly men
Vascular abnormality – lack of collagen support for small blood vessels and loss of subcutaneous fat and elastic fibers
Clinical features – dark blotches, age spots
Laboratory features – lab tests normal and no bleeding manifestations


Inducing drugs – aspirin, barbituates, diuretics, digoxin, methyldopa
Clinical features – petechiae, antibodies to vessel wall components,


Miscellaneous causes of vascular purpura

Dietary insufficiency – lack of vitamin C (ascorbic acid) – scurvy and decreased synthesis of collagen
Cause unknown

what does warfarin do?

reduces factor II, VII IX, X, protein C, protein S and protein Z and prolongs PT

Specimen collection tubes

plastic blue stopper with0.105 to 0.109 mol/L buffered sodium citrate anticoagulant

Ratio of blood to anticoagulant

9:1 with 3.2% sodium citrate

Rules of collection

venous whole blood, first tube to be collected or immediately after nonadditive tube, must not be collected after an additive tube as the additive might transfer to the coagulation tube and invalidate the coagulation tests

Hemostasis collection errors that require collection of a new specimen

lipemia, icterus, clot, short draw, hemolysis, prolonged tourniquet application- elevated the concentration of von willebrand factor and factor VIII and shortens the measured time on clot based assays, storage at 1-6C- precipitation of VWF and destruction of PLTs, storage at >25C- factor VIII deterioration

Collecting from indwelling catheters

Collected by special trained personnel
Line must be flushed with saline
Discard 5 mL of blood before collection
Heparin must not be used to flush

needle gauge for 25 mL specimens


needle gauge for >25 mL specimens

19 gauge

needle gauge for pediatric use

23 gauge, negative pressure must be reduced

Adjustment for high hematocrits
9:1 blood to anticoagulant is effective for hematocrit of 55% or less.
C = (13) (100-H) V
C = volume of sodium citrate in milliliters, V = volume of whole blood-sodium citrate solution in milliliters, H- hematocrit in percent

EDTA is used for

factor V Leiden and prothrombin G20210A mutation

heparinized anticoagulant is used for

platelet satelitosis

CTAD blue stopper used for

to halt in vitro plt or coagulation activation 4 specialty testing: plt factor 4, plt surface membrane p- selectin prothrombin activation markers

Storage times
Prothrombin time (PT)

may be held uncentrifuged at 18°-24°C for up to 24 hours

Storage times. Activated partial thromboplastin time (APTT)

centrifuged and supernatant transferred within 1 hour if patient is on unfractionated heparin to prevent shortening of of the PF4. tested within 4 hours

Storage requirements
Platelet aggregometry studies

Whole blood collected in 3.2% sodium citrate held at 18 to 24°C. Chilling destroys platelet activity. Aggregometry must be completed within 3 hours collection. Mix gently check for clots
Whole blood aggregometry specimen is diluted1:1 with normal saline – if plt count< 100000 specimen is tested undiluted

Light-transmittance optical aggregometers use

rich plasma with platelet count 200,000 to 300,000 /mcL. Sodium citrate plasma used
Check for clots. Centrifuge at 50g for 30 mins with stopper in place to maintain pH
Test is started 30 mins after centrifugation and completed within 3 hours collection. Light transmittance aggregometry is unreliable for platelet <100,00/mcL

Clot-based plasma testing use

platelet poor plasma with platelet count less than 10,000/mcL. Sodium citrate-anticoagulated blood is centrifuged at 1500 xg for 15 mins in a centrifuge at 4400xg for 3 mins
Double spin approach. >10,000 platelets/mcL affects clot based test. Platelets become activated in vitro and release membrane phospholipid phosphotidylserine

Can be stored frozen at

-20°C for 2 weeks or at -70°C for 6 months
When ready to be tested:
Thaw rapidly at 37C, mix well and test within 1 hou

platelet function tests

Bleeding time
Platelet aggregometry
Platelet lumi-aggregometry
Tests for heparin induced thrombocytopenia (HIT)

bleeding time

original test for platelet function now replaced by PFA- 100 or platelet aggregometry

Disorders with prolonged bleeding time

von Willebrand disease
Vascular disorder – scurvy or vasculitis

Problems with bleeding time test

inadequate predictive value
Affected by intracapillary pressure
Skin thickness at puncture site
Size and depth of wound

Platelet adhesion, aggregation, and secretion are assesed by

platelet aggregometry

Process of aggregation requires

platelet membranes and platelet activation pathways are intact and plasma fibrinogen concentration is normal
Specimen requirements – citrated whole blood or platelet rich plasma
Procedure using platelet-rich plasma (PRP)

PRP aggregometry uses

specialized photometer called a light transmittance aggregometer

Platelet processes measured –simultaneous measurement of platelet aggregation and secretion of adenosine triphosphate from activated platelet δ granules

platelet lumiaggregometry

platelet agonists, platelet aggregometry

Thrombin or synthetic thrombin receptor-activating peptide (TRAP)
Adenosine diphosphate (ADP)
Epinephrine, Collagen
Arachidonic acid, Ristocetin

Normal results – normal concentration of functional VWF and platelets possess a functional VWF receptor, GP Ib/V/IX
Abnormal results except for subtype 2B VW produce a reduced or absent reaction although alll other agonists generate normal tracings

Ristocetin-induced aggregation test (RIPA), Platelet aggregometry in VWF disease

conditions detected from platelet lumiaggregometry

Aspirin and Nonsteroidal anti-inflammatory drugs and clopidogrel
Platelet release defects – Eicosanoid Pathway Enzyme deficiencies – secretion and aggregation are diminished in response to ADP, epinephrine, collagen and arachidonic acid
Aspirin like disorders

conditions detected from platelet lumiaggregometry

Platelet storage pool defects – ATP release in response to thrombin is reduced as in response to ADP, epinephrine, arachidonic acid and collagen
Platelet membrane defects: Thrombasthenia – characterized by dysfunction or loss of GP IIb/IIIa receptor site
Acquired platelet disorders