ICD Body System
Date amended:
Statements of Principles
Current RMA Instruments
Reasonable Hypothesis SOP
91 of 2021
Balance of Probabilities SOP
92 of 2021
Changes from previous Instruments


 ICD Coding
  • ICD-9-CM Codes: 238.71
  • ICD-10-AM Codes: D47.3
Brief description

This is a blood/bone marrow disorder in which an excessive number of platelets (thrombocytes) are produced.    Essential thrombocythaemia is one of the chronic myeloproliferative neoplasm and is now classified as a malignant neoplasm.

Platelets are primarily involved in blood clotting.  The increase in platelets in this condition leads to abnormal thrombosis (clots) and associated haemorrhages.  However, this condition can be asymptomatic for years and picked up incidentally following a routine full blood count.

Confirming the diagnosis 

This diagnosis is complex and requires the exclusion of secondary causes.  Investigations will include repeated laboratory studies and a bone marrow apsirate and biopsy.

The relevant medical specialist is a haematologist.

Additional diagnoses covered by SOP
  • Essential haemorrhagic thrombocythaemia
  • Idiopathic thrombocythaemia
  • Essential thrombocytosis
Conditions excluded from SOP
  • Secondary thrombocythaemia due to:
    • Chronic myeloid leaukaemia*
    • Myelodysplastic syndrome*
    • Polycythaemia vera*
    • Primary myelofibrosis*

* another SOP applies

Clinical onset

Many cases are discovered incidently based on a blood count performed for another reason.  Some patients present with signs of thrombosis or bleeding.  Other present with non-specific symptoms from vasomotor disturbance such as headache or dizziness.

Clinical worsening

The only SOP worsening factor is for inability to obtain appropriate clinical management.  Treatment is aimed at preventing complications of thrombosis and haemorrhage, and alleviating symptoms.  There is no treatment currently available that is curative or will prolong survival.  Most patients have a normal life expectancy.  The condition may transform into acute myeloid leukaemia.  When that occurs it is a new onset of the leukaemia and not a worsening of the thrombocythaemia.