Warning

Audience

  • Highland HSCP
  • Primary and Secondary Care.
  • Adults only 

Introduction

Thrombocytosis is a common finding and is a frequent cause of referral for further investigation. There is a wide range of primary (eg, essential thrombocythaemia (ET), other myeloproliferative neoplasm MPN) and secondary causes as well as false or ‘spurious’ conditions mimicking thrombocytosis. Much less commonly there is a primary cause (eg, ET, other MPN). Establishing the cause therefore requires consideration of clinical features, haematological parameters and other test results.

The most common secondary (or reactive) causes of thrombocytosis are infection, inflammation, iron deficiency, tissue damage, haemolysis, severe exercise, malignancy, hyposplenism and other causes of an acute phase response. These are usually, but not always, characterized by an elevated C-reactive protein.

Pathway

Presentation

Identified on FBC, either incidentally or in the context of other clinical features.

Management in Primary Care

  • Check ferritin, CRP, blood film.
  • Exclude other causes of inflammation, including infection, malignancy, surgery.
  • History to include above, and specifically if there has been previous splenectomy.
  • Further imaging may be helpful to inform the assessment.
  • JAK2/CALR/MPL/BCR::ABL molecular mutation testing if no other obvious explanation. 
    If positive this is specific for primary causes of thrombocytosis (although a negative result does not exclude it), but the majority of cases are secondary.
  • Further investigation: this will be directed by secondary care after referral or consultation.

Note re ICE test availability (Nov 2023):

There has been a delay in the next set of tests to be included in the next addition for ICE. Any test not already on ICE can be requested using the 'Test not listed on ICE' functionality (users should have received training by the eHealth facilitators). NB: a paper request can be sent for infrequent or unusual requests.

Referral

  • JAK2/CALR/MPL/BCR::ABL mutation positive cases.
  • Mutation negative cases in the absence of another precipitant.

Management in Secondary Care

  • As per primary care guidance.
  • Note that molecular testing may be best deferred to community testing in order to exclude reactive thrombocytosis in the context of illness.

Escalation criteria

Associated thrombosis or bleeding.

Abbreviations

Abbreviation  Meaning 
BCR::ABL fusion gene associated with chronic myeloid leukaemia and thrombocytosis ("Philadelphia chromosome")
ET  essential thrombocythemia 
FBC  full blood count 
JAK2, CALR and MPL genes whose mutations may confer primary myeloproliferative neoplasms
MPN  myeloproliferative neoplasm 

Editorial Information

Last reviewed: 21/08/2023

Next review date: 31/08/2026

Author(s): Haematology .

Version: V1

Approved By: APPROVED TAM SG of ATDC

Reviewer name(s): Dr F Buckley, Consultant Haematologist.

Document Id: TAM585

Related resources

Further information for Health Care Professionals

(Scroll down to see all references)

References

Further information for Patients

Self-management information