Raised Platelets (Thrombocytosis)

Investigation and Referral Guidance


Refer through Choose and Book if:

1)         Platelet count > 500 x 109/l persisting for > 6 months


There is no reactive cause


Iron stores are normal .


2)         Platelet count > 450 x 109/l


      There is other evidence of a myeloproliferative disorder


Intermediate and difficult cases may be referred for advice through choose and book.


Secondary (reactive) thrombocytosis is common

Causes include:

  • Infection
  • Inflammation
  • Iron deficiency
  • Tissue damage (eg recent surgery, injury)
  • Haemolysis
  • Severe exercise
  • Malignancy (and rebound after chemotherapy)
  • Hyposplenism (splenectomy, coeliac disease)
  • and other causes of an acute phase response. These are usually, but not always, characterized by an elevated C-reactive protein.


Primary (myeloproliferative) essential thrombocytosis’ is rare and is suggested by:

  • Splenomegaly
  • Thromboembolism
  • Raised red cell count (+/-  hypochromic indices suggesting iron deficient polycythaemia)
  • Unexplained neutrophil leucocytosis

Patients are at risk of both thrombosis and of haemorrhage.

Recommended initial examination and tests:

History and examination to distinguish potential primary and secondary causes

FBC and blood film




Initial management

The management of secondary thrombocytosis is the management of the underlying disorder.

Correct and investigate iron deficiency.

Beware iron deficient polycythaemia.