Solving the Thrombocytopenia Puzzle with Immature Platelet Testing

Monday, November 20, 2017

New advances in hematology testing offer parameters useful in assessing challenging conditions such as thrombocytopenia. The immature platelet fraction (IPF) is an available parameter on analyzers in some laboratories. When used with patient information and platelet counts, the IPF can help the clinician with the differential diagnosis of thrombocytopenia.

IPF is a direct cellular measurement of platelet activity in the bone marrow and can help differentiate between productive and destructive causes of thrombocytopenia. Thrombocytopenic samples with low to normal IPF are often consistent with a platelet production disorder related to conditions such as aplastic anemia, leukemia, bone marrow suppression or the effect of drugs. On the other hand, thrombocytopenic samples with higher than normal IPF are often consistent with platelet destruction disorders such as immune thrombocytopenic purpura (ITP), thrombotic thrombocytopenic purpura (TTP), disseminated intravascular coagulation (DIC), drug toxicity or other destructive causes.

The immature platelets are easily seen on the platelet scattergram of certain hematology analyzers. These images are from the Sysmex XN-1000 which highlight differences between normal and abnormal cell populations:

The treatment and care for these conditions are very different. The option for a quick and inexpensive test that does not require another invasive blood draw is significant. The Cancer and Hematology Centers of Western Michigan found IPF to be extremely valuable with their challenging patients. The following case study demonstrates how IPF provided clinically significant data which improved the care this patient received.

Patient History/Presentation: 29-year-old healthy female presented to her physician with unexplained bruising and petechiae. Patient reported having a viral illness four weeks prior to developing symptoms. Patient reported a history of thrombocytopenia at age 2 that resolved spontaneously without intervention. Her physical exam was otherwise normal, with no evidence of end organ damage.

Diagnosis: Idiopathic thrombocytopenic purpura (ITP) secondary to viral illness

Treatment Plan and Follow Up:

Day 1: Patient admitted to hospital and started on Prednisone 1 mg/kg dose (IPF was 46 percent and low PLT count, consistent with a platelet destruction disorder)

Day 2: Laboratory tests showing clinically negligible increase in PLT count and IPF elevated, indicating continued bone marrow response

Day 3: PLT count remained low with elevated IPF. Additional medication was prescribed (Immune Globulin 1 g/kg intravenous infusion for two days)

Day 4: PLT count doubled and IPF decreased, but still above normal range showing continued recovery

Day 5: Patient discharged on oral Prednisone dosage of 90mg daily and weekly CBC blood laboratory assessment to monitor therapy

The Value of IPF

  • Direct cellular measurement of thrombopoietic activity in bone marrow
  • Increased IPF may indicate increased thrombopoiesis in bone marrow, with subsequent increased PLT count in peripheral blood
  • Relevant data that may contribute to treatment decisions
  • Part of CBC, using the same lavender tube
  • Results obtained quickly without additional drain on resources
  • Minimal cost and no discomfort compared to invasive diagnostic testing

In summary, IPF is a valuable laboratory parameter that may provide clinicians with the missing piece to the thrombocytopenia puzzle.

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