What Is Immune-Mediated Thrombocytopenia?

Immune-mediated thrombocytopenia is a reduction in platelet count caused by immune hypersensitivity. It is commonly a secondary medical condition associated with an underlying medical problem like cancer, although it can also appear on its own as a primary issue. Patients with abnormal platelet counts typically need a thorough workup to determine the cause and develop a treatment plan; with immune-mediated thrombocytopenia, treatment can be frustrating because the patient’s own body is essentially battling its platelets.

Hypersensitivity reactions occur when the immune system mistakenly identifies proteins associated with the body’s own products as foreign. It is not uncommon for such reactions to arise after an illness like cancer, where the patient’s immune system may be compromised and confused. When it spots these proteins, such as those present on the surface of a platelet, it triggers a response to destroy the associated cell. Circulating platelet counts drop because the immune system destroys them faster than they can be produced in the bone marrow.

Patients with immune-mediated thrombocytopenia can have symptoms like fatigue, pallor, and frequent bruising. Their blood doesn’t clot as well and they can be at risk of serious internal bleeding, damage to the joints, and blood loss associated with significant injuries. Transfusions of platelets can help address the immediate issue, but further diagnostic testing is necessary to find out why the patient’s immune system has decided platelets are hostile invaders.

Immunosuppressive medications like steroids can be a component of treatment for immune-mediated thrombocytopenia. These drugs blunt immune responses to allow the platelets time to recover, but doctors may not recommend them in the long-term because they can come with certain risks. For example, the patient is more vulnerable to infection and must be careful about being in environments where infectious agents are present. People may also need to avoid vaccination if their immune systems are compromised by medications.

In cases of secondary immune-mediated thrombocytopenia, treating the underlying condition may allow the platelets to recover. If the patient has an autoimmune disorder, this may require lifelong medication with immunosuppressants as well as monitoring for complications. Primary cases may be more challenging to address because once the immune system starts identifying a protein as dangerous, it will continue to so. This learned immunity is critical for protection from infection throughout life, but can be inconvenient when the immune system mistakenly targets the body with its robust and often highly effective defense system.