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Thrombocytosis-elevated platelet count

Thrombocytosis or raised -Platelet count of greater than 450 x 109 also called Thrombocythaemia

Try and determine the cause – present in 1.5 to 2.2 % of 
the people aged > 40 seen in primary care REACTIVE-Overproduction of platelets- acute phase reactants More common ↑↑ cytokines due to any reason Platelet count normalizes or is expected to return to normal once the condition resolves Acute and chronic infection Haemorrhage Trauma , tissue damage Surgery Acute and chronic inflammatory conditions Rheumatological disorders Inflammatory bowel disease Coeliac disease Iron deficiency anaemia Hemolytic anaemia Post- splenectomy Solid malignancies Severe exercise Usually but not always associated with an ↑ ESR or CRP Platelets normally small with a normal mean platelet volume Blood film may show other features to indicate acute infective or inflammatory process

CLONAL-Clonal expansion of megakaryocytes Failure to regulate platelet production Myeloproloferative or myelodysplastic disorders Essential thrombocythaemia or 
essential thrombocytosis Chronic myeloid leukaemia – CML Polycythemia vera Primary myelofibrosis

Risk of myeloproliferative disorders is increased if presentation is with ↑ platelets along with erythrocytosis , leukocytosis , thrombosis or splenomegaly

history-Recent trauma or surgery Splenectomy Symptoms of infection or inflammation Bleeding , thrombosis or iron deficiency Any haematological diagnosis Constitutional symptoms – r/o malignancy
○ weight loss
○ fatigue
○ systemic complains Medications

Complications –Vasomotor symptoms
Headache , visual symptoms , light-headedness ,
 atypical chest pain , syncope , erythromelalgia ( redness & pain of
 the digits of hand /feet ) , acrocyanosis 
and visual changes Thrombosis Bleeding complications- from skin , gums or nose and
 blockage of arteries ( particularyl extreme thrombocytosis ) Splenomegaly 
Liver may also be enlarged

Risk of cancer and 
thrombocytosis- BJGP 2017 
the incidence of cancer rose 
with age & with a higher 
platelet count & atleast 1/3rd of patients with lung and colorectal cancer with pre-disgnosis thrombocytosis had no other symptoms indicative of 

Tests-FBC , Peripheral blood film , Ferritin Inflammatory markers as CRP , ESR , Plasma fibrinogen Reticulocyte count- r/o hemolytic anaemia Bone marrow aspirate or BM Trephine biopsy Molecular genetics

Referral- Platelet count > 1000 Platelet count 600-1000 and associated
○ recent arterial or venous thromboembolism
○ neurological symptoms
○ abnormal bleeding
○ age > 60 yrs Persistent unexplained counts > 600 on atleast two occasions 4-6 wks apart Persistent platelet count 450-600 in association with
○ previous h/o arterial or venous thrombosis
○ splenomegaly
○ elevated Hb or WCC Suspected or confirmed clonal cause Suspected malignancy

Reactive-Self limited Treat the underlying condition Little excess associated thrombotic risk Treat iron deficiency if present No antiplatelet therapy recommended


  1. Investigation and Management of Adults and Children Presenting with Thrombocytosis British Journal of Haematology British Committee for Standards in Haematology 2011
  2. Essential thrombocytosis BMJ Best Practice
  3. Thrombocytosis Victoria Brown MD et al Ferri’s Clinical Advisor 2018
  4. Thrombocytosis : Diagnostic Evaluation, Thrombotic Risk Stratification , and Risk-Based Management Strategies  2011;2011:536062. doi: 10.1155/2011/536062. Epub 2011 Jun 8
  5. Oxford Handbook of Clinical Haematology
  6. Approach to the patient with thrombocytosis accessed via
  7. Patient UK Thrombocytosis Clinical relevance of thrombocytosis in primary care : a retrospective cohort study of cancer incidence using English electronic medical records and cancer registry data Br J Gen Pract May 2017
  8. First Consult- Evaluation and initial management of thrombocytosis
  9. Investigating thrombocytosis BMJ 2019 ;366 : I4183 July 2019
  10. Basildon and Thurrock University Hospitals Thrombocytosis- GP Referral; guidelines



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