Disorders of Platelets and Hemostasis Overview

Splenic Sequestration

Platelets sequestered in spleen causing thrombocytopenia.

Normal Platelet Lifespan

Platelet turnover lasts 7 to 10 days.

Pseudothrombocytopenia

False low platelet count due to aggregation.

Clotted Specimens

Specimens causing platelet activation are rejected.

Thrombocytosis

Elevated platelet count over 450,000/μL.

Platelet Structure

Anucleated cell fragments from metamegakaryocytes.

Primary Hemostasis

Initial stage involving platelet function.

Glycoprotein Receptors

Platelet function relies on specific receptors.

Alpha-Granules

Type of cytoplasmic granule in platelets.

Dense Granules

Another type of cytoplasmic granule in platelets.

Platelet Activation

Process before forming the platelet plug.

Platelet Adhesion

Binding of platelets to blood vessel surface.

Platelet Aggregation

Clumping of platelets to form a plug.

Secretion Function

Platelets release granules to activate others.

Thrombopoietin (TPO)

Main regulator of platelet production from liver.

Erythropoietin

Regulates red blood cell production from kidneys.

Normal Platelet Count

Healthy range is 150,000-450,000/mm³.

Bernard-Soulier Disease

Condition affecting platelet adhesion function.

Glanzmann's Thrombasthenia

Condition affecting platelet aggregation function.

Storage Pool Disorders

Defects in platelet secretion function.

von Willebrand Disease

Qualitative platelet disorder affecting adhesion.

Thrombocytopenia

Platelet count <150,000/μL.

Complete Blood Count (CBC)

Initial test for screening platelet disorders.

Decreased Production

Reduced platelet production due to various factors.

Thrombopoietin

Hormone produced in liver, regulates platelet production.

Mucocutaneous bleeding

Bleeding from mucous membranes or skin.

Peripheral Blood Smear

Examination to assess platelet size and morphology.

Autoimmune States

Conditions causing increased destruction of platelets.

Giant Platelet Syndromes

Associated with large platelets in blood.

Aplastic Anemia

Decreased or absent blood cell production in marrow.

Amegakaryocytic Thrombocytopenia

Severe thrombocytopenia with absent megakaryocytes.

Leukemia

Hyperproliferation of WBC precursor cells.

Bernard-Soulier Syndrome

Inherited disorder affecting platelet adhesion.

Glanzmann's Thrombasthenia

Deficient platelet aggregation due to receptor absence.

von Willebrand Disease (VWD)

Bleeding disorder due to vWF deficiency.

Platelet Adhesion

Platelets' ability to stick to non-platelet surfaces.

Platelet Aggregation

Platelets' ability to stick to each other.

Bleeding Time

Test assessing platelet adhesion function, 3-12 min.

Storage Pool Deficiency

Deficiency of platelet granules affecting activation.

Ristocetin-Induced Aggregation

Test for platelet aggregation via vWF.

Thromboxane A2

Molecule crucial for platelet aggregation.

Myeloproliferative Neoplasms

Disorders causing excessive blood cell production.

Uremia

Impaired platelet function due to kidney failure.

Peripheral Blood Smear

Assessment of platelet size and morphology.

Qualitative Platelet Disorders

Disorders affecting platelet functionality, not count.

Quantitative Platelet Disorders

Disorders affecting platelet count.

Drugs Inducing Thrombocytopenia

Medications causing low platelet counts.

Acquired von Willebrand Syndrome

Loss of vWF function due to other conditions.

Collagen Exposure

Triggers platelet adhesion during vascular injury.

Fibrinogen

Protein that bridges platelets during aggregation.

Glycoprotein Ib/IX

Receptor for vWF on platelet surface.

Hyperinfiltration

Bone marrow filled with WBC precursors.

Normal Platelet Count

Associated with specific qualitative disorders.

Platelet Function Tests

Assess platelet aggregation and secretion capabilities.

Extravasation

Leakage of blood components from vessels.

Platelet Transfusions

Used to manage severe bleeding episodes.

Characteristic Laboratory Abnormalities

Specific findings in platelet disorders.

Inherited Platelet Disorders

Genetic conditions affecting platelet function.

Acquired Platelet Disorders

Non-hereditary conditions affecting platelet function.

Normal Platelet Aggregation

Occurs with certain agonists, indicating function.

Hemorrhagic Stroke

Stroke caused by bleeding in the brain.

Ischemic Stroke

Stroke caused by blood clot in vessels.

Thrombocytopenia Symptoms

Manifestations include easy bruising and bleeding.

Normal Platelet Morphology

Indicates healthy platelet structure and function.

Blood Vessel Integrity

Critical for preventing bleeding and maintaining function.

Release defect

Impaired release of granules from platelets.

Dense granules deficiency

Absence of dense granules in platelets.

Endothelial cell

Cell lining blood vessel interiors.

Collagen exposure

Collagen becomes accessible during trauma.

Negatively charged collagen

Collagen has a negative electrical charge.

Platelet charge

Platelets are negatively charged due to glycoproteins.

Von Willebrand factor

Protein bridging platelets and collagen.

Granule release

Process where platelets release stored substances.

Hereditary platelet disorder

Genetic condition affecting platelet function.

Mucocutaneous bleeding

Bleeding from mucous membranes and skin.

Electron microscopy

Technique revealing dense granule absence.

Glycoprotein 2B3A

Receptor activated on platelets during aggregation.

Platelet activation

Process where platelets become reactive to stimuli.

Fibrinogen

A protein essential for blood clotting.

von Willebrand disease

A bleeding disorder caused by von Willebrand factor defects.

Thrombocytopenia

Platelet count less than 150,000 cells/mm³.

Immune-mediated thrombocytopenia

Thrombocytopenia caused by immune system disorders.

Idiopathic thrombocytopenic purpura (ITP)

Autoantibodies cause premature platelet destruction.

Drug-induced thrombocytopenia

Thrombocytopenia resulting from medication effects.

Collagen vascular disease

Disorders affecting connective tissue and blood vessels.

Lymphoproliferative disease

Diseases characterized by excessive lymphocyte production.

Sarcoidosis

Inflammatory disease affecting multiple organs.

von Willebrand factor

A protein that helps platelets adhere to blood vessels.

Bernard-Soulier syndrome

Defect in glycoprotein 1B and 9 affecting platelets.

Granule deficiency

Insufficient storage or release of platelet granules.

Glanzmann's Thrombasthenia

Defect in glycoprotein 2B3A affecting platelet aggregation.

Thrombocytosis

Increased platelet count above 450,000 cells/mm³.

Dilutional thrombocytopenia

Thrombocytopenia due to dilution from fluid replacement.

Sequestration in enlarged spleen

Platelets trapped in an enlarged spleen.

Microangiopathic hemolytic anemia

Anemia due to small blood vessel damage.

Aplastic anemia

Bone marrow fails to produce sufficient blood cells.

Megakaryocytic conditions

Conditions affecting the production of megakaryocytes.

Petechiae

Small red or purple spots from bleeding under skin.

Bystander lysis

Cell damage due to immune complex deposition.

Platelet Lifespan

Platelets live 7 to 10 days in blood.