From the Guidelines
Thrombocytopenia is primarily caused by decreased production, increased destruction, or sequestration of platelets, with immune thrombocytopenia (ITP) being a common cause of increased destruction, as noted in the 2019 American Society of Hematology guidelines 1.
Causes of Thrombocytopenia
Thrombocytopenia, characterized by abnormally low platelet counts below 150,000 per microliter, has numerous causes that can be categorized into three main mechanisms:
- Decreased production, which occurs in bone marrow disorders like leukemia, aplastic anemia, myelodysplastic syndromes, vitamin B12 or folate deficiency, and as a side effect of chemotherapy or radiation.
- Increased destruction, which happens in immune thrombocytopenia (ITP), thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), disseminated intravascular coagulation (DIC), and with certain medications like heparin (causing heparin-induced thrombocytopenia).
- Sequestration of platelets, which occurs in conditions with splenomegaly such as liver cirrhosis or portal hypertension.
Medications and Infections
Common medications that can cause thrombocytopenia include antibiotics (sulfonamides, vancomycin), anticonvulsants (phenytoin, carbamazepine), and certain anti-inflammatory drugs. Infections, particularly viral infections like HIV, hepatitis C, and COVID-19, can also trigger thrombocytopenia, as discussed in various studies 1.
Management and Treatment
Understanding the underlying mechanism is crucial for appropriate management, which may range from treating the underlying condition to platelet transfusions in severe cases with bleeding. The decision to transfuse platelets is complex and depends on various factors, including the patient's risk of bleeding, comorbidities, and lifestyle, as outlined in the guidelines for platelet transfusion 1.
Key Considerations
The management of thrombocytopenia should prioritize the prevention of bleeding and the treatment of the underlying cause, with a focus on improving the patient's quality of life and reducing morbidity and mortality, as emphasized in the 2019 American Society of Hematology guidelines for ITP 1. In clinical practice, the threshold for prophylactic platelet transfusion in patients with solid tumors is generally considered to be 10,000/mL or less, although this may vary depending on individual patient factors and the presence of necrotic tumor sites, as discussed in the guidelines for platelet transfusion 1.
From the Research
Causes of Thrombocytopenia
- Decreased platelet production 2, 3, 4
- Increased platelet destruction 2, 3, 4
- Splenic sequestration 2, 3, 4
- Dilution or clumping 2, 3
- Drug-induced thrombocytopenia 2, 4
- Immune thrombocytopenia 2, 4
- Hepatic disease 2
- Vitamin B12 deficiency 5, 6
- Heparin-induced thrombocytopenia 2
- Thrombotic microangiopathies 2, 6
- Hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome 2
- Antiphospholipid syndrome 2
- Congenital thrombocytopenias 3
- Essential (primary) thrombocythemia 4
- Reactive (secondary) thrombocytosis 4