What is the appropriate workup for thrombocytopenia (low platelet count)?

From the Guidelines

The workup for thrombocytopenia should begin with a complete blood count (CBC) with peripheral smear, reticulocyte count, and a thorough history and physical examination, as recommended by the most recent guidelines 1. The initial evaluation should focus on identifying the underlying cause of thrombocytopenia, including medication use, recent infections, family history, and bleeding symptoms.

• A thorough history should include questions about viral illnesses, lymphocyte-depleting therapy, steroids, and cytotoxic therapy.
• Physical examination should look for signs of bleeding, lymphadenopathy, hepatosplenomegaly, and other systemic conditions.
• Laboratory testing should include liver function tests, renal function tests, coagulation studies (PT, PTT), and consideration of specialized tests based on clinical suspicion, such as HIV testing, hepatitis serologies, antiphospholipid antibodies, and direct antiglobulin test.
• For suspected immune thrombocytopenia (ITP), bone marrow examination may be necessary if abnormalities are found in the initial testing results and further investigation is necessary for a diagnosis, as suggested by the guidelines 1.
• The urgency and extent of workup depend on the platelet count, rate of decline, and presence of bleeding, with severe thrombocytopenia (<20,000/μL) or active bleeding requiring immediate evaluation and management.
• In patients with newly diagnosed ITP, testing for HIV, HCV, HBV, and H. pylori should be performed, as well as a direct antigen test to rule out concurrent Evans’ syndrome, as recommended by the guidelines 1. The most recent and highest quality study 1 provides a comprehensive approach to the workup and management of thrombocytopenia, emphasizing the importance of a thorough history, physical examination, and laboratory testing to identify the underlying cause and guide treatment selection.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Diagnostic Workup for Thrombocytopenia

• The diagnostic work-up for thrombocytopenia should exclude other causes of thrombocytopenia and secondary immune thrombocytopenia (ITP), including myelodysplastic syndrome and drug-induced ITP 2.
• The treatment decision is influenced by an increased risk of bleeding, infectious diseases, and thrombosis in certain populations, such as older adults, and should take into account comorbidities and concomitant medications such as anticoagulant drugs 2.

First-Line Treatment

• First-line treatment for ITP is based on short corticosteroids courses and intravenous immunoglobulin, which should be reserved for patients with more severe bleeding complications 2.
• Corticosteroids and intravenous immunoglobulins (IVIG) are the front-line standard therapy for ITP, based on the immunologic mechanism of the disease 3.

Second-Line Treatment

• Second-line treatment should be tailored to the patient's history, comorbidities, and preferences 2.
• Preferred second-line treatments are thrombopoietin receptor agonists, such as romiplostim and eltrombopag, for most groups and guidelines given their good efficacy/tolerance ratio 4, 2.
• Other second-line options that can be good alternatives depending on the clinical context include rituximab, dapsone, fostamatinib, or immunosuppressive drugs 2.
• Romiplostim appears to have slightly fewer adverse effects and higher costs compared to eltrombopag 4.
• Switching between thrombopoietin receptor agonists (TRAs) is a successful way to overcome adverse effects and inadequacy according to the currently available literature 4.

Special Considerations

• In older adults, the incidence of ITP increases after age 60 years and peaks in patients over age 80 years, making ITP a concern for physicians taking care of older patients 2.
• The thrombotic risk is increased in older people, and thrombopoietin receptor agonists should be used with caution in this population 2.
• Emerging treatments such as Syk or Bruton tyrosine kinase inhibitors and FcRn antagonists are becoming available for ITP and may modify the treatment algorithm in the near future 2.