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Immune system
Sepsis
Neonatal sepsis
Abscesses
Type I hypersensitivity
Food allergy
Anaphylaxis
Asthma
Type II hypersensitivity
Immune thrombocytopenic purpura
Autoimmune hemolytic anemia
Hemolytic disease of the newborn
Goodpasture syndrome
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Myasthenia gravis
Graves disease
Pemphigus vulgaris
Type III hypersensitivity
Serum sickness
Systemic lupus erythematosus
Poststreptococcal glomerulonephritis
Type IV hypersensitivity
Graft-versus-host disease
Contact dermatitis
Transplant rejection
Graft-versus-host disease
Cytomegalovirus infection after transplant (NORD)
Post-transplant lymphoproliferative disorders (NORD)
X-linked agammaglobulinemia
Selective immunoglobulin A deficiency
Common variable immunodeficiency
IgG subclass deficiency
Hyperimmunoglobulin E syndrome
Isolated primary immunoglobulin M deficiency
Thymic aplasia
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Adenosine deaminase deficiency
Ataxia-telangiectasia
Hyper IgM syndrome
Wiskott-Aldrich syndrome
Leukocyte adhesion deficiency
Chediak-Higashi syndrome
Chronic granulomatous disease
Complement deficiency
Hereditary angioedema
Asplenia
Thymoma
Ruptured spleen
Blood transfusion reactions and transplant rejection: Pathology review
Immunodeficiencies: T-cell and B-cell disorders: Pathology review
Immunodeficiencies: Combined T-cell and B-cell disorders: Pathology review
Immunodeficiencies: Phagocyte and complement dysfunction: Pathology review
Immune thrombocytopenic purpura
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Laboratory value | Result |
Hematologic | |
Hemoglobin | 12 g/dL |
Hematocrit | 40% |
Platelet count | 95,000/mm3 |
Leukocyte count | 9,000/mm3 |
Coagulation studies | |
Prothrombin time (PT) | 12 seconds |
Activated partial thromboplastin time (aPTT) | 29 seconds |
Bleeding time* | 15 minutes |
Robyn Hughes, MScBMC
Evan Debevec-McKenney
Immune thrombocytopenic purpura or ITP is an autoimmune condition in which the body produces antibodies against its own thrombocytes or platelets, which are destroyed. And this result in purpura, or small bleeding spots beneath the skin.
Normally, when there’s any kind of damage to the blood vessel, hemostasis occurs, which is the process that stops the bleeding and plugs the damaged vessel to limit the blood loss.
And there are two steps: primary and secondary hemostasis. During primary hemostasis, platelets aggregate to form a plug at the site of an injured blood vessel.
Platelet aggregation is mediated by surface proteins found on platelets, called GP2B3A receptors. While these platelets are aggregating, secondary hemostasis kicks in.
Secondary hemostasis is also called coagulation, because that’s when clotting factors come into play one after another, with a view to cleaving fibrinogen into fibrin.
Then, fibrin forms a protein mesh, kinda like a giant net that covers the platelet plug and stabilizes it.
Now, in ITP, the spleen produces certain IgG autoantibodies which bind to the platelet receptor Gp2B3A, and target the platelet-antibody complexes for destruction in the spleen.
This leads to lowering of platelet counts in the blood, which makes it harder for bleeding to stop. Now, ITP can be acute or chronic.
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