MedSchool: Ace Your OSCEsThe Medical Company
GET - On the App Store
Full Blood Count

Platelet Count

February 15th, 2021


Platelets are very small non-nucleated cells that derive from fragmentation of megakaryocytes. They play an important role in clot formation and haemostasis.
    • Normal Range

    • 150 - 400 x 10⁹/L


Thrombosis refers to an increase in circulating platelets. This may occur due to a myeloproliferative neoplasm, a reactive increase in platelet production, or a shift in platelets from the spleen into the circulation.
  • Causes of Thrombocytosis

  • Primary

  • Myeloproliferative neoplasms - essential thrombocythaemia, polycythaemia vera, chronic myeloid leukaemia, myelofibrosis
  • Increased Production

  • Infection
  • Inflammation - autoimmune disease, major surgery, trauma, fracture, burns, pancreatitis, infarction
  • Malignancy
  • Drugs - adrenaline, corticosteroids, vinca alkaloids, thrombopoietin
  • Acute haemorrhage
  • Iron deficiency
  • Platelet Shift

  • Hyposplenism - splenectomy, liver cirrhosis, coeliac disease, sickle cell disease, SLE


Reduced circulating platelets.
  • Causes of Thrombocytopaenia

  • Reduced Production

  • Congenital thrombocytopaenia - e.g. May-Hegglin, Bernard-Soulier
  • Bone marrow failure - aplastic anaemia, paroxysmal nocturnal haemoglobinuria
  • Bone marrow suppression - cytotoxic chemotherapy, radiotherapy, alcohol abuse
  • Bone marrow infiltration - leukaemia, multiple myeloma, lymphoma, metastasis, myelofibrosis
  • Myelodysplasia
  • B12 / folate deficiency
  • Increased Destruction

  • Autoimmune thrombocytopaenia - immune thrombocytopaenic purpura (ITP), SLE, antiphospholipid syndrome, rheumatoid arthritis
  • Alloimmune thrombocytopaenia - transfusion reaction
  • Drug-induced immune thrombocytopaenia - heparin-induced thrombocytopaenia (HIT), quinine, bactrim, vancomycin, rifampin, paracetamol, NSAIDs, glycoprotein IIb/IIIa inhibitors
  • Infection - HIV, hepatitis C, EBV, CMV, H pylori, sepsis
  • Thrombotic microangiopathies - thrombotic thrombocytopaenic purpura (TTP), haemolytic-uraemic syndrome (HUS), disseminated intravascular coagulation (DIC), HELLP syndrome
  • Gestation thrombocytopaenia 
  • Splenic Sequestration

  • Hypersplenism
  • Factitious

  • Platelet clumping
  • Haemodilution (e.g. massive transfusion)
Next Page
Want more info like this?
  • Your electronic clinical medicine handbook
  • Guides to help pass your exams
  • Tools every medical student needs
  • Quick diagrams to have the answers, fast
  • Quizzes to test your knowledge
Sign Up Now

Snapshot: Initialising...