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

From the Guidelines

Thrombocytopenia workup typically begins with a thorough medical history and physical examination, followed by laboratory tests including a complete blood count (CBC) with platelet count, blood smear, and reticulocyte count 1.

Initial Evaluation

• A complete medical history to identify potential underlying causes, such as viral illnesses, lymphocyte depleting therapy, or family history of autoimmunity 1
• Physical examination to assess for signs of bleeding or splenomegaly 1
• Laboratory tests, including:
  • CBC with platelet count to confirm thrombocytopenia 1
  • Blood smear to evaluate platelet morphology and rule out other causes of thrombocytopenia 1
  • Reticulocyte count to assess bone marrow function 1

Additional Testing

• Patients with risk factors for HIV, HCV, HBV, or H. pylori infection should be tested for these conditions 1
• Bone marrow evaluation may be necessary if abnormalities are found on initial testing or if further investigation is needed to establish a diagnosis 1
• Direct antigen test to rule out concurrent Evans’ syndrome 1
• Nutritional evaluation to assess for potential contributing factors 1

Management

• Medications that may exacerbate thrombocytopenia, such as heparin or aspirin, should be discontinued if possible 1
• Patients may be started on corticosteroids, such as prednisone 1mg/kg/day, for a duration of 2-4 weeks to manage immune-mediated thrombocytopenia 1

From the Research

Evaluation of Thrombocytopenia

The evaluation of thrombocytopenia involves several steps to determine the underlying cause and appropriate management. According to 2, the first step is to exclude pseudothrombocytopenia by collecting blood in a tube containing heparin or sodium citrate and repeating the platelet count.

Distinguishing Acute from Chronic Thrombocytopenia

If thrombocytopenia is confirmed, the next step is to distinguish acute from chronic thrombocytopenia by obtaining or reviewing previous platelet counts 2. Patients with acute thrombocytopenia may require hospitalization, especially if they have conditions such as heparin-induced thrombocytopenia, thrombotic microangiopathies, or the hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome.

Common Causes of Thrombocytopenia

Common causes of thrombocytopenia include:

• Drug-induced thrombocytopenia
• Immune thrombocytopenia
• Hepatic disease
• Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome
• Disseminated intravascular coagulation
• Hematologic disorders 2, 3, 4

Diagnostic Approach

The diagnostic approach to thrombocytopenia involves a comprehensive history and physical examination, complete blood count, and review of the peripheral blood smear 5. A thorough medical history should be performed, and screening for any signs of bleeding should be done 6.

Management of Thrombocytopenia

The management of thrombocytopenia depends on the underlying cause and severity of the condition. According to 2, transfusion of platelets is recommended when patients have active hemorrhage or when platelet counts are less than 10 × 10^3 per μL. Patients with platelet counts of less than 50 × 10^3 per μL should adhere to activity restrictions to avoid trauma-associated bleeding.

Emergency Situations

Emergency situations that require immediate attention include:

• Active bleeding
• Biological signs of disseminated intravascular coagulation
• Acute renal failure
• Platelet count < 30 × 10^3 per μL (or < 50 × 10^3 per μL if the patient is on anticoagulation or antiplatelet therapy)
• Significant and/or brutal onset pancytopenia 6