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Heparin-induced Thrombocytopenia

  • Cynthia M. Johnson, MA
Publication Type:


Heparin-induced Thrombocytopenia

(HIT; Heparin-induced Low Blood Platelet Count)


Thrombocytopenia means low blood platelet count. Platelets are a special type of blood cell. They help form clots so a person does not bleed too much.

Heparin is a blood thinner that lowers the risk of blood clots. Heparin-induced thrombocytopenia (HIT) is low blood platelet count caused by heparin. It can lead to too much blood clotting. Too much bleeding is rare.

Clot Formation.

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HIT is caused by platelets clumping due to an immune reaction to heparin. The clumping uses them up and lowers the count.

Risk Factors

Taking heparin is a risk for having HIT.


Symptoms of HIT are from blood vessels being blocked:

  • Pain or swelling in the legs
  • Chest pain
  • Problems breathing
  • Anxiety
  • Sweating
  • Fast, uneven heartbeats
  • Headache


The doctor will ask about symptoms and past health. A physical exam will be done.

Blood tests will be done to check the platelet count.


Treatment may include:

  • Stopping the use of heparin.
  • Blood thinners to lower the risk of blood clots.
  • Vitamin K antagonists (VKA) therapy—in people taking a VKA, it will be stopped and vitamin K will be given; the VKA will be started again when the person's platelet count is normal.
  • Platelet transfusion may be given to replace used up platelets if there is a lot of bleeding, but this is rare.


To lower the risk of HIT:

  • Avoid heparin use.
  • Take other blood thinners.




  • Arepally GM. Heparin-induced thrombocytopenia. Blood. 2017;129(21):2864-2872.
  • Heparin-induced thrombocytopenia (HIT). EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/heparin-induced-thrombocytopenia-hit.
  • Heparin sodium. EBSCO Nursing Reference Center Plus website. Available at: https://www.ebsco.com/health-care/products/nursing-reference-center-plus.


  • Dianne Scheinberg Rishikof MS, RD, LDN
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.