Hematopathology Lecture 5: Coagulation Disorders

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Questions and Answers

What is the main growth factor for platelet production?

Prostocycline (PGI2)

Thromboxane A2 (TXA2)

Adenosine Diphosphate (ADP)

Thrombopoietin (TPO) (correct)

What is the normal platelet count in adult blood?

100 - 300 x 109/L

250 - 600 x 109/L

150 - 400 x 109/L (correct)

200 - 500 x 109/L

What is the process by which platelets are produced in the bone marrow?

Thrombopoiesis

Megakaryopoiesis (correct)

Leukopoiesis

Erythropoiesis

What is the function of ADP in platelets?

Promote platelet aggregation Signup and view all the answers

What is the function of Prostocycline (PGI2) in platelets?

Inhibit platelet aggregation Signup and view all the answers

What is the half-life of most coagulation factors?

10-65 hours Signup and view all the answers

What is the normal half-life of platelets?

7-10 days Signup and view all the answers

What percentage of platelets are normally trapped in the spleen?

1/3 Signup and view all the answers

What is the term for bleeding in the joint?

Hemarthrosis Signup and view all the answers

What is the purpose of adding sodium citrate to the blood sample tube?

To prevent coagulation Signup and view all the answers

What is the term for pinpoint flat round red spots caused by intradermal hemorrhage?

Petechiae Signup and view all the answers

What type of bleeding disorder is characterized by extravasation of RBC into skin and subcutaneous tissue?

Purpura Signup and view all the answers

What is the normal range for Prothrombin Time (PT)?

11-15 seconds Signup and view all the answers

What investigation is NOT used for bleeding disorders?

Serum Signup and view all the answers

What is the term for dilated superficial capillaries that blanch with pressure?

Telangiectasia Signup and view all the answers

What is the term for redness of the skin due to increased blood flow that blanches with pressure?

Erythema Signup and view all the answers

What type of bleeding is associated with platelet disorders?

Superficial bleeding Signup and view all the answers

What is the purpose of Prothrombin Time (PT) in coagulation studies?

To assess extrinsic and common pathways Signup and view all the answers

What is the main cause of thrombocytopenia?

Increased platelet consumption Signup and view all the answers

What is the function of Fibrinogen assay in coagulation studies?

To assess the last stage of coagulation Signup and view all the answers

What is the classification of bleeding disorders that includes inherited or acquired coagulation factors deficiency or dysfunction?

Coagulation factors disorders Signup and view all the answers

Which of the following is a cause of thrombocytopenia?

Hypersplenism Signup and view all the answers

What is the purpose of Activated Partial Thromboplastine Time (APTT) in coagulation studies?

To assess intrinsic and common pathways Signup and view all the answers

What type of bleeding is associated with vascular disorders?

Superficial bleeding Signup and view all the answers

What is the characteristic of idiopathic thrombocytopenic purpura?

Chronic autoimmune thrombocytopenia, usually in young adults, without precedent or associated illness Signup and view all the answers

What is the typical site of platelet destruction in autoimmune thrombocytopenic purpura?

Spleen Signup and view all the answers

What is the characteristic of blood picture in autoimmune thrombocytopenic purpura?

Isolated thrombocytopenia with many giant platelets Signup and view all the answers

What is Evan's syndrome associated with?

ITP with warm autoimmune hemolytic anemia Signup and view all the answers

What is the significance of bone marrow examination in autoimmune thrombocytopenic purpura?

It is done to confirm the diagnosis and exclude serious diseases Signup and view all the answers

What is the triggering factor for autoantibody production in autoimmune thrombocytopenic purpura?

Any of the above Signup and view all the answers

What is the characteristic of acute post-viral autoimmune thrombocytopenia?

Acute usually self-limiting thrombocytopenic purpura, typically seen in children following acute viral infection or immunization Signup and view all the answers

What is the important diagnostic test for autoimmune thrombocytopenic purpura?

Clinical exclusion of other causes of thrombocytopenia and response to treatment with steroid Signup and view all the answers

What is the estimated percentage of acute ITP cases that recover spontaneously?

70-80% Signup and view all the answers

Which of the following is a contraindication for platelet transfusion?

Life-threatening bleeding Signup and view all the answers

What is the primary enzyme responsible for breaking down HMW multimer of vWF?

ADAMTS-13 Signup and view all the answers

Which of the following is a characteristic of thrombotic thrombocytopenic purpura?

Mild or no renal manifestation Signup and view all the answers

What is the primary treatment for hemolytic uremic syndrome?

Supportive management for renal function Signup and view all the answers

Which of the following is NOT a characteristic of hemolytic uremic syndrome?

Neurological manifestation Signup and view all the answers

What is the primary cause of hemolytic uremic syndrome?

E. coli infection Signup and view all the answers

Which of the following is a treatment option for refractory thrombotic thrombocytopenic purpura?

Immunosuppression Signup and view all the answers

Study Notes

Hemostasis and Blood Coagulation

Hemostasis is the physiological arrest of hemorrhage at sites of vascular injury
5 systems involved in hemostasis:
- Platelets
- Blood vessel
- Coagulation factors
- Natural coagulation inhibitors
- Fibrinolytic system

Platelets

Produced in the bone marrow through megakaryopoiesis
Normal platelet count in adult blood: 150-400 x 10^9/L
Normal half-life of platelet: 7-10 days, with 1/3 of platelets trapped in the spleen
Function in primary hemostasis through:
- Adhesion
- Shape changes
- Aggregation
- Release of mediators
ADP and TXA2 are major positive mediators for platelet aggregation
PGI2 (prostocycline) is a potent inhibitor of platelet aggregation

Coagulation Pathways

All coagulation factors synthesized in the liver
Half-life of all factors: 10-65 hours, except F7 (5-7 hours)
Final insoluble stable fibrin strands formed

Disorders of Coagulation System

Bleeding disorders
Thrombosis

Bleeding Manifestations

Petechiae: pinpoint flat red spots caused by intradermal hemorrhage
Ecchymoses: extravasation of RBC into skin and subcutaneous tissue, 0.2-10 mm
Hematomas: bleeding in the muscle
Hemarthroses: bleeding in the joint
Hemoptysis, hematemesis, hematuria, conjunctival hemorrhage, epistaxis

Investigations of Bleeding Tendency

Sample preparation: citrated plasma using special tube containing sodium citrate as anticoagulant
Investigations:
- CBC (complete blood count) and blood film
- Bleeding time (BT)
- Prothrombin time (PT)
- Activated partial thromboplastin time (APTT)
- Fibrinogen assay (FNG)

Classification of Bleeding Disorders

Platelet disorders: reduction in platelet count (thrombocytopenia) or platelet dysfunction
Coagulation factors disorders: inherited or acquired coagulation factors deficiency or dysfunction
Vascular disorders: inherited or acquired
Less frequently, disorders in inhibitors and fibrinolytic system

Platelet Disorders

Abnormal bleeding associated with platelet disorders characterized by superficial bleeding (skin and mucous membrane) and post-traumatic
Causes of thrombocytopenia:
- Reduced production of platelets
- Increased platelet consumption
- Abnormal distribution: hypersplenism

Autoimmune Thrombocytopenic Purpura (ITP)

Chronic autoimmune thrombocytopenia, usually in young adults, without precedent or associated illness
Can be classified into:
- Idiopathic thrombocytopenic purpura
- Secondary autoimmune thrombocytopenia
- Acute post-viral autoimmune thrombocytopenia
Clinically: usually present with purpura overall the body, sparing abdomen, in acute or chronic pattern of presentation
Pathogenesis: triggering factors induce autoAb production against specific antigen on platelet, which is removed by macrophage in the spleen
Hematological findings:
- Blood picture showing isolated thrombocytopenia usually severe < 20 x 10^9/L with many giant platelets
- Evan's syndrome: association of ITP with warm autoimmune hemolytic anemia
- Bone marrow: usually normal cellularity with increased or normal number of megakaryocytes

Treatment of ITP

Acute ITP: 70-80% of cases are spontaneously recovered; some patients may require treatment mainly with prednisolone
Chronic ITP: usually needs treatment with corticosteroid, splenectomy, IV Ig, and immunosuppression
Platelet transfusion for life-threatening bleeding, but it is contraindicated

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Description

This quiz covers the learning objectives of Lecture 5 on Hematopathology, focusing on coagulation disorders, including the components of normal coagulation systems, bleeding tendencies, and patient presentation.