From the Guidelines
Thrombocytopenia is primarily caused by decreased platelet production, increased platelet destruction, or abnormal platelet sequestration, with immune thrombocytopenia (ITP) being a leading cause of increased destruction, as supported by the American Society of Hematology 2011 evidence-based practice guideline for immune thrombocytopenia 1. The causes of thrombocytopenia can be categorized into three main mechanisms:
- Decreased platelet production, which occurs in conditions like bone marrow failure (aplastic anemia, leukemia), vitamin deficiencies (B12, folate), or as a side effect of medications such as chemotherapy drugs, heparin, sulfonamides, and quinine.
- Increased platelet destruction, which happens in immune thrombocytopenia (ITP), where the immune system attacks platelets, or in conditions like disseminated intravascular coagulation (DIC), thrombotic thrombocytopenic purpura (TTP), and hemolytic uremic syndrome (HUS).
- Abnormal platelet sequestration, which occurs when platelets become trapped in an enlarged spleen (hypersplenism) due to liver disease or certain blood disorders. Other causes of thrombocytopenia include infections like HIV, hepatitis C, and sepsis, which can trigger platelet destruction, as well as pregnancy, which can cause gestational thrombocytopenia, and alcohol abuse, which damages bone marrow stem cells 1. It is essential to recognize these causes to provide proper diagnosis and treatment, as management depends on addressing the underlying condition rather than just the low platelet count itself, and the investigation and management of ITP patients vary widely, with the purpose of providing recommendations relating to diagnosis and treatment 1. The most critical step in managing thrombocytopenia is to identify the underlying cause, as treatment strategies differ significantly depending on the etiology, and a thorough history, physical examination, and initial blood counts and smear are necessary to distinguish between true thrombocytopenia and pseudothrombocytopenia 1.
From the FDA Drug Label
Heparin-induced thrombocytopenia (HIT) is a serious antibody-mediated reaction. HIT occurs in patients treated with heparin and is due to the development of antibodies to a platelet Factor 4-heparin complex that induce in vivo platelet aggregation Thrombocytopenia in patients receiving heparin has been reported at frequencies up to 30%. It can occur 2 to 20 days (average 5 to 9) following the onset of heparin therapy. Causes of thrombocytopenia include:
- Heparin-induced thrombocytopenia (HIT)
- Heparin-induced thrombocytopenia with thrombosis (HITT)
- Other medical conditions or diseases, such as immune thrombocytopenia (ITP), chronic hepatitis C virus (HCV) infection, or severe aplastic anemia (SAA) 2 Note that thrombocytopenia can also be caused by other factors not related to heparin therapy, such as certain medical conditions or diseases, but these are not explicitly mentioned in the provided drug label as causes of thrombocytopenia related to the use of heparin or eltrombopag 3
From the Research
Causes of Thrombocytopenia
Thrombocytopenia can occur due to various reasons, including:
- Decreased platelet production 4, 5, 6
- Increased destruction of platelets 4, 5, 7
- Splenic sequestration 4, 6
- Dilution or clumping of platelets 4
- Infections 5
- Malignancy 5, 8
- Liver disease 4, 5
- Autoimmune disorders 5, 7
- Disseminated intravascular coagulation 5
- Pregnancy 5
- Medications 4, 5
- Coagulation disorders 5
- Bone marrow failure 8
Specific Causes
Some specific causes of thrombocytopenia include:
- Immune thrombocytopenia (ITP) 4, 7
- Drug-induced thrombocytopenia 4
- Heparin-induced thrombocytopenia 4
- Thrombotic microangiopathies 4
- Hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome 4
- Antiphospholipid syndrome 4
- Congenital thrombocytopenias 6
Clinical Presentation
The clinical presentation of thrombocytopenia can vary from asymptomatic to severe bleeding, depending on the platelet count 4. Patients with platelet counts greater than 50 × 10^3 per μL are generally asymptomatic, while those with platelet counts between 20 and 50 × 10^3 per μL may have mild skin manifestations such as petechiae, purpura, or ecchymosis 4. Patients with platelet counts of less than 10 × 10^3 per μL have a high risk of serious bleeding 4.