Self-Evaluation: Platelets and Primary Hemostasis
Secondary hemostasis
Activation of coagulation proteins
Sites of bleeding in patients with thrombocytopenia are usually: deep muscle tissues external skin and mucous membranes joints all of the above
external skin and mucous membranes
A patient with a platelet count of 16 x 109/L might have which of the following symptoms? petechiae intracranial bleeding profuse bleeding from cuts in the skin all of the above
petechiae intracranial bleeding profuse bleeding from cuts in the skin all of the above
Aggergation
When forming the primary hemostatic plug, _________________ requires fibrinogen and the fibrinogen receptor.
Adhesion
When forming the primary hemostatic plug, _________________ requires von Willebrand factor and its receptor.
Which platelet count is consistent with thrombocytosis? 200 x 10^9/L 20 x 10^9/L 2000 x 10^9/L 2 x 10^9/L
2000 x 10^9/L
Which of the following are platelet agonists? endothelial cells and collagen prostacyclin and nitric oxide ADP, collagen, and thrombin von Willebrand factor and glycoprotein Ib
ADP, collagen, and thrombin
Glanzmann's Thrombasthenia
Absence or decrease of GPIIb/IIIa complex
NAIT
Antibodies directed against platelet antigens of a newborn
Acute ITP
Antibody to patient's own platelets. Affects age 2-4 with spontaneous remission.
Chronic ITP
Antibody to patient's own platelets. Occurs more in females age 20-50. Diagnosis of exclusion.
Platelet Aggregation Pattern: ADP and EPI = Primary wave; AA = suppressed response
Aspirin ingestion
TXA2
Aspirin results in irreversible inactivation of the platelet enzyme cyclo-oxygenase and inhibition of _________________ synthesis for the life of the platelet. This means there will be no secretion of platelet granules.
A patient with a severe nosebleed was seen in the emergency room of your hospital. When performing the evaluation of the peripheral blood smear, you noticed that at least 75% of the platelets were large or giant size. The platelets had abnormal morphology and appeared to have a large complement of granules. What condition may this patient have? Glanzmann's thrombasthenia essential thrombocythemia Bernard-Soulier syndrome Uremia
Bernard-Soulier syndrome
Platelet Aggregation Pattern: ADP, EPI, and Collagen = normal; Ristocetin and Ristocetin + vWF = no response
Bernard-Soulier syndrome
Test that measures platelet number and function. Lancet produces a standard wound that is blotted with filter paper until bleeding stops. PFA has replaced this test.
Bleeding time (Duke and Ivy methods)
Ecchymoses
Bruise greater than 3mm
Primary hemostatic plug
Clump of platelets that temporarily arrest bleeding
Bernard-Soulier syndrome
Decrease or abnormal function of GPIb/IX complex
Storage Pool Deficiencies
Defect of platelet granules.
Fibrinolysis
Digestion of fibrinogen and fibrin by plasmin
Platelet Aggregation Pattern: ADP, EPI, and Collagen = no response
Glanzmann's Thromasthenia
Secondary hemostatic plug
Hemostatic plug reinforced with insoluble fibrin
Which of the following is an acquired vascular disorder? hereditary hemorrhagic telangiectasia acute immune thrombocytopenia Henoch-Schoenlein purpura Marfan's syndrome
Henoch-Schoenlein purpura
Ehlers-Danlos syndrome
Hyperdistensible joints and skin
Uremia
Increased BUN causing plt dysfunction
Primary hemostasis
Interaction of platelets and vascular endothelium to stop bleeding following vascular injury
Thrombopoietin TPO
Platelet development is regulated by the hormone __________________.
The PFA must have a certain platelet count and hematocrit in order to produce accurate results. What must these values be?
Plt = 150, Hct = 35
von Willebrand Disease
Plt aggregation has no response with ristocetin. Increased PTT due to decreased factor VIII.
Purpura
Purple discoloration of skin 1 cm or greater
HIT
Recurrent thrombosis while on heparin
Petechiae
Small pinhead dots caused by blood escaping from capillaries
Hereditary Hemorrhagic Telangiectasia
Small vascular malformation of skin and mucous membranes
Platelet Aggregation Pattern: ADP and EPI = Primary wave; Ristocetin and AA = normal response
Storage pool disease
Structural
The cytoskeleton and contractile region of the platelet are located in the _________________ zone.
150-400
The normal concentration of platelets in the peripheral blood is about ___________ K/cmm.
PF3
This platelet factor is a phospholipid that allows for the assembly of vitamin K-dependent coagulation factors.
PF4
This platelet factor neutralizes heparin on the endothelial surface and promotes coagulation.
Post-Transfusion Purpura
Thrombocytopenia about 1 week after a platelet transfusion
Test that measures vascular integrity. Still used to diagnose Dengue infection
Tourniquet test or Rumpel-Leede
GPIIb/IIIa
_________________ is the platelet receptor for fibrinogen
GPIb/IX
_________________ is the platelet receptor for von Willebrand factor
Endomytosis
_________________ is when the nucleus undergoes multiple divisions with no cytoplasmic separation.
The parent compound from which thromboxane A2 is formed in the activated platelet is: ADP thrombin arachidonic acid von Willebrand factor
arachidonic acid
Vasoconstriction is a function of: platelets blood vessels erythrocytes hemostatic proteins in the plasma
blood vessels
In primary hemostasis, von Willebrand factor (VWF) functions as a(n): bridge between platelets and collagen in the subendothelium platelet agonist trigger for platelet "shape change" inhibitor of platelet aggregation
bridge between platelets and collagen in the subendothelium
Platelet aggregation is the process of: platelets binding to collagen platelets causing vasoconstriction platelets binding to one another platelets binding to endothelial cells
platelets binding to one another
Platelet Aggregation Pattern: ADP, EPI, Collagen, and Ristocetin + vWF = normal
von Willebrand disease