Platelet Disorders Flashcards
*What is the function of thrombopietin?
Regulate platelet production
What is the normal count of platelets?
150, 000-450, 000
- What is the normal life span of a platelet?
7-10 days
- Where are platelets produced?
In the liver and kidneys
- What amount of platelets is normally trapped in the spleen?
1/3 of platelet mass
- Describe the composition of platelets
Granules, membrane glycoproteins, membrane receptors
- What is the function of platelets?
To form a mechanical plug during normal hemostatic response to vascular injury
What are the 4 steps involved in platelet function?
Adhesion, activation, aggregation, and interaction with coagulation factors
What test is used to test the amount of platelets?
CBC
What is the most common cause of bleeding?
Platelet disorders
- Define thrombocytopenia
Decreased number of platelets or defective platelet function
What are the causes of thrombocytopenia?
- Underproduction of platelets
- Increased rate of platelet removal from circulation
- What are the clinical characterics of thrombocytopenia?
-Mucocutaneous bleeding (petechiae, confluent, purpura, ecchymosis) -Nose and/or gum bleeding -Heavy menstrual bleeding in women -Excessive bleeding after minor cute
*At which level should urgent platelet transfusion occur?
When platelet count < 10,000/L (regardless of clinical bleeding)
*At which level should platelet transfusion occur due to traumatic bleeding?
When platelet count is less than 50,000/L
- At which level should platelet transfusion occur due to clinical or spontaneous bleeding?
When the platelet count is less than 10,000 to 20,000/L.
*Define Immunothromboytopenia (ITP)
Autoimmune disorder characterized by platelets bound antibodies
*What is the etiology of Immunothrombocytopenia (ITP)?
Idiopathic
- Describe the diagnostic evaluation if ITP.
Diagnosis of exclusion: rule out all causes of thrombocytopenia; platelet antibody is non specific
- Describe treatment of ITP
- Steroids (mainly)
- IVIG
- Rituximab (antibod
- Splenectomy
-No treatment if platelet count >20K and non clinical hemorrhages
- What s/sx are associated with Thrombocytic thrombocytopenic purpura (TTP)?
- Classic “pentad” (40%)
- Fever
- Neurological symptoms
- Renal insufficiency
- Thrombocytopenia (petechiae)
- MAHA (hemolytic anemia)
- What treatment is used for thrombocytic thrombocytopenis putpura (TTP)?
- Plasma exchange (main)
- Rituximab
- Corticosteroid
*Define Hemolytic uremic syndrome (HUS)
a TMA that is characterized by the triad of hemolytic anemia (MAHA) , peripheral thrombocytopenia and renal failure in almost 100% of cases
- What s/sx present in HUS?
- Diarrhea 2-12 days & later b/C bloody 1-2 days after
- Intense Abd pain and painful defecation
- What is the etiology of HUS?
Intestingal infection with Siga-toxin producing bacteria
- Ecoli 0157: H7
- Shigella dysenteriae serotype 1
- What treatment is used for typical HUS?
(symptomatic) : Hemodialysis, BP control RX, fluid mgnt
- No NSAIDS, antibiotics, or narcotics
- What treatment is used for atypical HUS?
- Plasma exchange
- Eculizumab
What is Disseminated intravascular coagulopathy (DIC)
Pathological imbalance in the procoagulant and anticoagulant systems that lead to unregulated thrombin generation
- What is the treatment of DIC?
TREAT UNDERLYING DISEASE
- Clotting factor and inhibitor replacement
- Pharmacologic Inhibitors
*What are the characteristics of HELLP syndrome?
Hemolysis, Elevated Liver enzymes, and Low Platelets
*What is the treatment for HELLP syndrome?
Fetal extraction/delivery
- What is the function of the spleen?
- to remove particulates from the blood stream
- Remove senescent/deformed RBCs from circulation
- Trap and destroy antibody cotatefd platelets or RBC in pts with autoimmune disorders
- What percentage of platelets can reside in the spleenwith enlargement.
up to 90% in cases of extreme splenomegaly
- Define hyperspleenism
disorder which causes the spleen to rapidly and prematurely destroy blood cells.
*Define splenomegaly
Abnormal enlargement of the spleen
*What affect does Cardiopulmonary Bypass/ECMO have on platelets?
Platelets ACTIVATED by contact with ARTIFICIAL SURFACES during surgery
- What effect does Uremia have on platelets
Multifactorial including vascular abnormalities, anemia, and circulating metabolites cause defects in platelet function and adhesion
- What effect does myelopliferative disorders (MPD) have on platelets?
- Clonal abnormalities in megakaryocytes produces defective platelets
- Patient may present with hemorrhage or thrombosis
*What two congenital disorders of platelet formation cause a defect in platelet-vessel interaction?
- Von Willebrand disease
- Bernard-Soulier syndrom
- What defect does
Glanzmann Thrombasthenia have on platelets?
Causes defects in platelet-platelet interaction
What is the treatment for Glanzman thrombasthenia?
- Platelet transfusion (mainly)
- rFVIIa if platelet antibodies develop
- Bone marrow transplant
What is the normal MPV volume?
8-11
What disease presents with giant platelets?
Bernard-Soulier syndrome
What defect is present in Bernard-Soulier syndrome?
Defect in platelet membrane glycoprotein IB-IX (VWF receptor) which prevents platelets from adhering to BV
Which disorder presents with neutophil cytoplasmic inclusions (Dohle bodies)?
May-Hegglin Syndrome
What disorder presents with hypogranular platelets (absence of platelets)
Gray Platelet syndrome
Define thrombocytosis
platelet count greater than 450,000/microL
