What are the causes of thrombocytopenia (low platelet count)?

From the Guidelines

An isolated low platelet count, or thrombocytopenia, should be evaluated by a healthcare provider promptly, especially if the count is below 100,000 platelets per microliter, to reduce the risk of hemorrhage and improve quality of life, as recommended by the American Society of Hematology 2019 guidelines for immune thrombocytopenia 1.

Causes and Evaluation

Thrombocytopenia can result from decreased production in the bone marrow, increased destruction in the bloodstream, or splenic sequestration. Common causes include certain medications, viral infections, autoimmune disorders like immune thrombocytopenic purpura (ITP), pregnancy complications, or bone marrow disorders. The evaluation of thrombocytopenia should include a thorough medical history, physical examination, and laboratory tests to determine the underlying cause.

Management and Treatment

Treatment targets the underlying cause rather than the low platelet count itself, ranging from medication adjustments to immune therapies depending on the diagnosis. According to the American Society of Clinical Oncology clinical practice guideline update, prophylactic platelet transfusion should be administered to patients with thrombocytopenia resulting from impaired bone marrow function to reduce the risk of hemorrhage when the platelet count falls below a predefined threshold level 1. The management of ITP, a common cause of thrombocytopenia, should be individualized based on the patient's age, comorbidities, and disease severity, as recommended by the international consensus report on the investigation and management of primary immune thrombocytopenia 1.

Quality of Life and Mortality

Thrombocytopenia can have a significant impact on quality of life, particularly in the first year after diagnosis, related to restrictions on activities, anxiety due to the risk of bleeding, and the burden of treatment and monitoring 1. Adults with ITP have a 1.3- to 2.2-fold higher mortality than the general population due to cardiovascular disease, infection, and bleeding. Therefore, prompt evaluation and treatment of thrombocytopenia are crucial to improve quality of life and reduce mortality.

Additional Considerations

While awaiting medical care, patients with thrombocytopenia should avoid aspirin and NSAIDs like ibuprofen, which can affect platelet function, and be cautious with activities that could cause injury or bleeding. Other causes of isolated thrombocytopenia, such as heparin-induced thrombocytopenia, should also be considered, particularly in patients who have received heparin therapy 1.

From the Research

Definition and Causes of Isolated Low Platelet Count

• Isolated low platelet count, also known as thrombocytopenia, is a condition characterized by a platelet count of less than 150 × 10^3 per μL 2.
• Thrombocytopenia can occur due to decreased platelet production, increased destruction, splenic sequestration, or dilution or clumping 2.
• Patients with isolated thrombocytopenia in the absence of systemic illness most likely have immune thrombocytopenia or drug-induced thrombocytopenia 2.

Symptoms and Risk of Bleeding

• Patients with a platelet count greater than 50 × 10^3 per μL are generally asymptomatic 2.
• Patients with platelet counts between 20 and 50 × 10^3 per μL may have mild skin manifestations such as petechiae, purpura, or ecchymosis 2.
• Patients with platelet counts of less than 10 × 10^3 per μL have a high risk of serious bleeding 2.
• The risk of bleeding is decreased by ensuring adequate platelet counts before invasive procedures, which may require a platelet transfusion 2.

Diagnosis and Management

• The diagnosis of immune thrombocytopenia (ITP) is based principally on the exclusion of other causes of isolated thrombocytopenia using patient history, physical examination, blood count, and evaluation of the peripheral blood film 3.
• The clinical treatment goals should be to resolve bleeding events and to prevent severe bleeding episodes, with a target platelet count of > 20-30 × 10^9/L 3.
• Corticosteroids are considered the standard initial treatment for newly diagnosed patients with ITP 3.
• Subsequent medical therapies with robust evidence include thrombopoietin receptor agonists (TPO-RAs), rituximab, and fostamatinib 3.
• Surgical therapy with splenectomy may be considered for patients failing medical therapy 3.

Treatment Strategies

• Front-line standard therapy for ITP consists of corticosteroids and intravenous immunoglobulins (IVIG) 4.
• Second-line therapy for refractory ITP may consist of rituximab, thrombopoietin receptor agonists, splenectomy, or cytotoxic drugs 4.
• Recent clinical studies have indicated promising outcomes for novel drugs, either as single agents or in combination with traditional drugs 4.
• The choice between therapy options is highly dependent upon patient values and preferences 3.