Secondary Thrombocytosis Workup

Updated: Dec 24, 2018
  • Author: Koyamangalath Krishnan, MD, FRCP, FACP; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Laboratory Studies

The laboratory workup in cases of secondary thrombocytosis (reactive thrombocytosis) includes the following:

  • Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)

  • Cytogenetic analysis

  • Leukocyte alkaline phosphatase, vitamin B-12

  • Antinuclear antibody (ANA), rheumatoid factor (RF)

  • Iron studies (serum iron, total iron-binding capacity [TIBC], serum ferritin)

  • Peripheral blood smear review

If the clinical presentation does not clearly differentiate between primary (clonal) and secondary thrombocytosis, further tests may be indicated to exclude or confirm a diagnosis of disorders that cause clonal thrombocytosis, as follows:

  • Cytogenetic studies: The presence of the Philadelphia chromosome (Ph) found in chronic myelogenous leukemia (CML) may also be identified using reverse transcriptase-polymerase chain reaction (RT-PCR) to identify the bcr-abl fusion transcript or by using Southern blot analysis for identification of bcr-abl genomic rearrangements.

Essential thrombocythemia is a diagnosis of exclusion that is based on the following numeric criteria (adapted from Hoffman R. Primary thrombocythemia. In: Hoffman R, Benz EJ Jr, Shattil SJ, et al, eds. Hematology: Basic Principles and Practice. 3rd ed. Philadelphia, Pa: Churchill Livingstone; 2000:1188-204). [4] Patients who meet criteria 1-5 and more than three of criteria 6-11 are considered to have essential thrombocytosis.

  1. Platelet count greater than 600,000/mm3 on two occasions, separated by a 1-month interval

  2. Absence of an identifiable cause of secondary thrombocytosis

  3. Normal red blood cell mass

  4. Absence of significant bone marrow fibrosis (ie, less than one third of the bone marrow)

  5. Absence of the Philadelphia chromosome (Ph) by karyotyping or absence of the bcr-abl fusion product

  6. Splenomegaly by physical examination or ultrasonography

  7. Bone marrow hypercellularity with megakaryocyte hyperplasia

  8. Presence of abnormal bone marrow hematopoietic progenitor cells as determined by the growth of endogenous erythroid cells and/or megakaryocyte colonies with increased sensitivity to interleukin-3 (IL-3)

  9. Normal levels of CRP and IL-6

  10. Absence of iron deficiency anemia, as documented by either a normal bone marrow–stainable iron or normal serum ferritin level

  11. In females, demonstration of clonal hematopoiesis by restriction fragment length polymorphism (RFLP) analysis of genes present on the X chromosome


Imaging Studies

Perform an ultrasound of the abdomen if the presence of splenomegaly is uncertain.