ITP is an autoimmune disorder characterized by a unique immune system dysfunction that results in a diminished platelet count. This leads  to bleeding and easy bruising

What is Immune Thrombocytopenic Purpura (ITP)?

Introduction

Immune Thrombocytopenic Purpura (ITP) is an autoimmune condition marked by a reduced platelet count (thrombocytopenia) due to the immune system’s destruction of platelets. Platelets play a vital role in the coagulation of blood, and their deficiency can result in bleeding tendencies, such as purpura (purple skin spots), petechiae (tiny red spots), and bleeding from mucous membranes.

Types of ITP

ITP can be divided into two categories:

Acute vs. Chronic ITP:

• Acute ITP:
  • Typically observed in children, often following a viral illness. It generally resolves on its own.
• Chronic ITP:
  • More prevalent in adults, particularly women of reproductive age. It persists for over 12 months and may necessitate ongoing treatment.

Primary vs. Secondary ITP:

• Primary (Idiopathic) ITP:
  • The majority of cases of ITP are primary or idiopathic, meaning there is no clear underlying cause.
  • Primary ITP is characterized by an autoimmune response where the immune system mistakenly targets and destroys platelets.
  • Primary ITP can manifest as either acute or chronic, depending on the duration of thrombocytopenia.
• Secondary ( Acquired ) ITP:
  • Secondary ITP is associated with an underlying condition or trigger that contributes to the development of thrombocytopenia.
  • It can be secondary to autoimmune diseases such as systemic lupus erythematosus (SLE) or rheumatoid arthritis.
  • Certain infections, such as Helicobacter pylori, HIV, or hepatitis C, can lead to secondary ITP.
  • Some medications, like heparin or certain antibiotics, may induce secondary ITP.

Other Terminology or Types of ITP:

• Post-infectious ITP:
  • This type of ITP occurs after a viral or bacterial infection.
  • It is often seen in children and may follow a viral illness, such as mumps, rubella, or chickenpox.
  • Post-infectious ITP is typically acute and tends to resolve spontaneously.
• Recently diagnosed ITP:
  • pertains to ITP identified within the last 3 months.
• Chronic ITP:
  • Pertains to ITP that has persisted for 3 to 12 months.
• Severe ITP:
  • Pertains to ITP associated with notable bleeding symptoms necessitating further intervention.
• Refractory ITP:
  • Pertains to ITP cases that have not responded to therapy or have recurred.

Epidemiology

• 1 to 3 cases per 100,000 in Adults
• About 4 in 100,000 children
• More in children than in adults
• More in females compared to males.

Causes of ITP

• Autoimmune Response
• Infections:
  • Epstein-Barr virus (EBV), cytomegalovirus (CMV), and varicella-zoster virus (VZV)
  • H. pylori Infection
• Autoimmune Diseases:
  • systemic lupus erythematosus (SLE) and rheumatoid arthritis.
• Lymphoproliferative Disorders:
  • chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma
• Medications:
  • heparin, quinine, sulfonamides, and certain antiplatelet drugs
• Pregnancy:(due to changes in the immune system)
• Post-Vaccination ITP

Pathophysiology of ITP

The defining feature of ITP is the generation of autoantibodies, primarily IgG, that target antigens on the surface of platelets, notably glycoprotein IIb/IIIa. These platelets that are coated with antibodies are identified and eliminated by macrophages in the spleen, resulting in a decrease in platelet count. Furthermore, there may be a reduction in the production of platelets in the bone marrow, which could also play a role in the disease.

• Important points to remember:
  • Autoantibodies focus on glycoproteins found in platelets.
  • The spleen is crucial in the process of platelet destruction.
  • The bone marrow may exhibit an increase in megakaryocytes (the precursors of platelets) but may not produce platelets effectively.

Clinical Features of ITP

The clinical symptoms of ITP can differ based on the level of thrombocytopenia. Typical signs include:

• Skin changes: Petechiae, purpura, and bruising (ecchymoses).
• Bleeding from mucous membranes: Nosebleeds (epistaxis), bleeding gums (gingival bleeding), and heavy menstrual periods (menorrhagia).
• In severe instances: Intracranial bleeding or gastrointestinal bleeding may occur, but this is rare.
• In children: acute ITP often follows a viral infection and typically resolves on its own. In adults, chronic ITP might develop gradually with mild to moderate bleeding symptoms.

Diagnosis of ITP

The diagnosis of ITP involves clinical assessment combined with laboratory testing. It is mainly a diagnosis of exclusion, indicating that other causes of low platelet counts must be eliminated.

• Complete Blood Count (CBC): Reveals isolated thrombocytopenia (platelet count < 100,000/µL) while white blood cell and hemoglobin levels remain normal.
• Peripheral Blood Smear: Confirms thrombocytopenia and excludes other causes such as pseudothrombocytopenia or platelet clumping. Immature large platelets
• Bone Marrow Examination: Usually not necessary but may be conducted to rule out other blood disorders, particularly in unusual cases.
• Exclusion of Secondary Causes: Conditions like HIV, hepatitis C, lupus, or drug-induced thrombocytopenia should be ruled out.
• PAIgG test: (Platelet associated immunoglobulins IgG / IgM) positive

Treatment and Management Options for ITP

The management of ITP varies based on symptom severity, platelet levels, and the patient’s age. The aim is to prevent bleeding issues while minimizing the adverse effects of treatment.

• Initial Treatments:
  • Corticosteroids: Prednisone serves as the primary treatment. It reduces immune-mediated destruction of platelets.
  • Intravenous Immunoglobulin (IVIG): This is utilized for a quick increase in platelet count, particularly during acute bleeding episodes or prior to surgical procedures.
  • Anti-D Immunoglobulin: This is effective in patients who are Rh-positive and have not undergone splenectomy.
• Subsequent Treatments (for persistent or chronic ITP):
  • Splenectomy: This procedure eliminates the main site of platelet breakdown.
  • Thrombopoietin Receptor Agonists (TPO-RA): These drugs enhance platelet production (for example, romiplostim and eltrombopag).
  • Rituximab: This is a monoclonal antibody that targets B cells, helping to decrease the production of autoantibodies.
• Supportive Care:
  • Steer clear of medications that affect platelet function (such as aspirin and NSAIDs).
  • Administer antifibrinolytics (like tranexamic acid) for bleeding from mucosal surfaces.