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

From the Guidelines

Patients with chronic, stable, severe thrombocytopenia who are not receiving active treatment may be observed without prophylactic platelet transfusion, reserving platelet transfusions for episodes of hemorrhage or during times of active treatment. This approach is based on the American Society of Clinical Oncology's clinical practice guideline update from 2018 1, which suggests that many patients with sustained, severe thrombocytopenia, such as those with myelodysplasia or aplastic anemia, can have minimal or no significant bleeding for long periods despite low platelet counts.

Key Considerations

• The recommendation to observe without prophylactic transfusion is based on an informal consensus with intermediate evidence quality and moderate strength of recommendation 1.
• No randomized studies have been performed in patients with sustained, severe thrombocytopenia, but clinical experience suggests that many such patients do not experience significant bleeding.
• Platelet transfusions should be reserved for episodes of hemorrhage or during times of active treatment, as the risk of bleeding is higher in these situations.

Management of Thrombocytopenia

• Treatment of thrombocytopenia depends on the underlying cause and severity of the condition.
• For mild cases with no bleeding, monitoring may be sufficient.
• For more severe cases, treatments may include corticosteroids, intravenous immunoglobulin, or thrombopoietin receptor agonists.
• Patients should avoid medications that affect platelet function, such as aspirin and NSAIDs, and seek immediate medical attention for signs of serious bleeding.

From the FDA Drug Label

1. 3 Heparin-Induced Thrombocytopenia and Heparin-Induced Thrombocytopenia and Thrombosis Heparin-induced thrombocytopenia (HIT) is a serious antibody-mediated reaction.
2. 5 Thrombocytopenia 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. Obtain platelet counts before and periodically during heparin therapy. Monitor thrombocytopenia of any degree closely If the count falls below 100,000/mm3 or if recurrent thrombosis develops, promptly discontinue heparin, evaluate for HIT and HITT, and, if necessary, administer an alternative anticoagulant [see Warnings and Precautions (5.3)].

Thrombocytopenia is a potential side effect of heparin therapy, reported in up to 30% of patients. It can occur 2 to 20 days after starting heparin, with an average onset of 5 to 9 days.

• Key considerations:
  • Obtain platelet counts before and during heparin therapy
  • Monitor thrombocytopenia closely
  • Discontinue heparin if the platelet count falls below 100,000/mm3 or if recurrent thrombosis develops
  • Evaluate for HIT and HITT and consider alternative anticoagulants if necessary 2

From the Research

Definition and Causes of Thrombocytopenia

• Thrombocytopenia is defined as a platelet count of less than 150 × 10^3 per μL 3, 4.
• It can occur due to decreased platelet production, increased destruction, splenic sequestration, or dilution or clumping 3.
• Various mechanisms such as decreased platelet production, sequestration, destruction, consumption, and sometimes a combination of these factors contribute to thrombocytopenia 5.

Symptoms and Risk of Bleeding

• Patients with a platelet count greater than 50 × 10^3 per μL are generally asymptomatic 3, 4.
• Patients with platelet counts between 20 and 50 × 10^3 per μL may have mild skin manifestations such as petechiae, purpura, or ecchymosis 3.
• Patients with platelet counts of less than 10 × 10^3 per μL have a high risk of serious bleeding 3, 4.

Diagnosis and Management

• The first step in evaluating thrombocytopenia is to exclude pseudothrombocytopenia by collecting blood in a tube containing heparin or sodium citrate and repeating the platelet count 3.
• Patients with acute thrombocytopenia may require hospitalization, while those with chronic thrombocytopenia can often be managed as outpatients 3.
• Platelet transfusion is recommended when patients have active hemorrhage or when platelet counts are less than 10 × 10^3 per μL, in addition to treatment of underlying causative conditions 3, 6.
• The management strategies are aimed at treating the underlying disorder, such as platelet transfusion to treat complications like bleeding 5.

Specific Conditions Associated with Thrombocytopenia

• Heparin-induced thrombocytopenia (HIT) is a relatively infrequent complication of heparin administration that can cause devastating thrombosis 7.
• Thrombotic microangiopathies, and the hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome are conditions that require emergency hospitalization 3.
• Antiphospholipid syndrome is a condition in which bleeding and thrombosis can occur 3.

Treatment and Platelet Transfusion

• Intravenous immunoglobulin (IVIG) may be the optimal treatment for patients with severe heparin-induced thrombocytopenia 7.
• Platelet transfusion represents the primary supportive treatment of thrombocytopenia to prevent or treat bleeding 6.
• The platelet count transfusion threshold to secure invasive procedures remains based on a low level of evidence 6.