Platelet Disorders Flashcards
Qualitative and quantitative PLT disorders may cause what kind of bleeding symptoms: (7)
- Gingival (gum) bleeding
- Epistaxis (nose bleed)
- Ecchymosis (excessive bruising)
- Petechiae (small hemorrhage spots)
- Purpura (hemorrhage into skin, mucous menbranes (on slide))
- Prolonged bleeding
- Menorrhadia (excessive bleeding after tooth surgery)
What is the normal PLT range?
150 - 450 x 109/L
A decreased PLT count causes bleeding / results in what symptoms? (4)
- ginigival bleeding
- Epistaxis
- Ecchymosis
- Petichiae
<60 x 109/L PLT count may lead to
bleeding in surgery
<30 x 109/L PLT count may lead to
Petechial Bleeding
<5 x 109/L PLT count may lead to
risk bleeding into CNS
What pre-analytical variables may cause a decreased PLT count? (5)
- Incorrect sample handling
- Blood reacting with EDTA
- Bone marrow funtion (Aplasia - lack of megakaryocytes)
- Cancer (blas cells crown out normal PLT producing cells)
- Chemotherapy; may destroy PLT producing cells.
What are 5 consumption of PLT disorders?
- Idiopathic (immune) thrombocytopenia purpura (ITP)
- Thrombotic thrombocytopenic purpura (TTP)
- Hemolytic Uremic Syndrome (HUS)
- Altered distribution of PLTs (spleen traps PLTs)
- Destruction by RES (spleen removes antidrug antibody coated PLTs)
Coagulation samples are drawn in what tube?
Blue top (sodium citrate)
What is the blood:anticoag ratio?
9:1 (tube must be 90% full)
What is PLT satellitetism?
Leads to?
Corrective action?
PLTs form a righ around seg neutrophils, monocytes, and bands.
Leads to falsely low PLT count
sample redrawn in blue tube
What is Neonatal Alloimmune Thrombocytopenia?
- Occurs as a result of materal antibody made against PLT antigens from earlier pregnancy.
- Antibody is against HPA-1a PLT
- IgG can cross placenta
- Infants born have normal PLTs, but soon develop petechia and skin hemorrhages
When is Neonatal Alloimmune Thrombocytopenia treated?
only when there is a risk of CNS hemorrhage
What is Idiopathic Thrombocytopenic Purpura?
The autoantibody IgG is against?
Decreased PLT count becuse of immune destruction
- Gp IIb/IIIa or GpIb-IX
What is Thrombotic Thrombocytopenic Purpura (TTP)?
- Deficiency of protein ADAMTS-13, which normally cleaves vWF into smaller proteins. This may lead to excessive PLT clots.
What is the PLT level in Thrombotic Thrombocytopenic Purpura (TTP)?
- PLT .20 x 109/L
What is the key factor differentiating Thrombotic Thrombocytopenic Purpura (TTP) from Idiopathic Thrombocytopenia Purpura? (5)
- Microangiopathic Anemia (MHA)
- Schistocytes and severe anemia
- Increased LDH
- Decreased Haptoglobin
- Hemoglobinuria
What are the clinical symptoms of Thrombotic Thrombocytopenic Purpura (TTP)?
- Neurologic symptoms
- Fever
- Renal failure
- Thrombocytopenia
T/F: PT and aPTT is in normal reference range in Thrombotic Thrombocytopenic Purpura (TTP)?
- True
Renal damage resulting from a toxin produced by E.coli O157:H7, the Shiga toxin leads to cell death in Kidneys.
Hemolytic Uremic Syndrome (HUS)
Hemolytic Uremic Syndrome (HUS) mimics what disorder?
TTP
Clinical symptoms the same except no neurological symptoms
Inherited Adhesion Disorder: Von Willebrand Disease genetics?
Symptoms?
What is VWF?
- Auto Dominant
- Ecchymosis, Epistaxis, menorrhagia, and excessive bleeding after tooth extraction.
- Intermediary for PLT adhesion and a receptor for GpIIb/IIIa
What is the sinlgle best predictive assay for vWF antigen?
Ristocetin co-factor activity.
Inherited Adhesion Disorder: What is Bernard Soulier syndrome and its genetics? (3)
- Adhesion defect of PLTs involving Gp Ib/IX complex
- Abscence of ristiocetin induced PLT aggregation
- Autosomal recessive (rare)
Inherited Aggregation Disorder: Glanzmann’s thombasthenia
Genetics?
What is abnormal?
Clinical symptoms?
How is aggregation affected?
Bleeding patterns?
- Rare Auto. recessive
- Abnormality of Gp IIb/IIIa
- prolonged bleeding time
- Abnormal with all aggregating agents EXCEPT ristocetin
- Variable
Acquired defects of PLT function: Drug related abnormalities?
What is the most common drug?
What does it cause? (2)
- Aspirin
- Inhibits PLT aggregator Thromboxane A2
- Proloned Bleeding Time
Acquired defects of PLT function: Extrinsic PLT abnormalities bare caused by? (2)
- Uremia due to renal disease
- Hyperviscosity and paraproteinemia
- multiple myeloma
Acquired defects of PLT function: Waldenstrom’s mscroglobulinemia?
What causes this?
What does this prevent?
- IgM interferes with PLTs
- PLTs circulating in abnormal amounts of protein cannot fully participate in the activation of coagulation factors and fibrin formation.
What are the Lab tests for PLT function for the below?
- PLT function analyzers
- Von Willebrand’s disease
- PLT aggregation
- PLT function analyzers - collagen/epinephrine or collagen /ADP membranes
- vWD antigen measured by immuno assay - Rictocetin
- Lumi-aggregometer - based in impedence
What are PLT aggregation tests used for?
Asses PLT function
What does the ristocetin cofactor assay assess?
vWF Function by measuring ristocetin-meadiated binding of vWF to PLT GpIb
What happens to PLT aggregation in Glanzmann’s thrombasthenia?
aggregation is decreased with all agonists (ADP, collagen, epinephriine, arachidonate) EXCEPT ristocetin.
