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by EBSCO Medical Review Board
(HIT; Heparin-induced Low Blood Platelet Count)

Definition

Thrombocytopenia means low blood platelet count. These are a special type of blood cell. They help form clots so that you do 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
blood clot platelet
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Causes

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 this health problem.

Symptoms

Symptoms are from blood vessels being blocked:

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

Diagnosis

You will be asked about your symptoms and health history. An exam will be done.

Blood tests will be done to check your platelet count.

Treatment

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.

Prevention

To lower the chance of this problem:

  • Avoid heparin use.
  • Take other blood thinners.

RESOURCES

American Heart Association  http://www.heart.org 

Family Doctor—American Academy of Family Physicians  http://familydoctor.org 

CANADIAN RESOURCES

Canadian Cardiovascular Society  http://www.ccs.ca 

Heart and Stroke Foundation of Canada  http://www.heartandstroke.com 

References

Arepally GM. Heparin-induced thrombocytopenia. Blood. 2017 May 25;129(21):2864-2872.

Heparin-induced thrombocytopenia (HIT). EBSCO DynaMed website. Available at:  https://www.dynamed.com/condition/heparin-induced-thrombocytopenia-hit . Updated August 30, 2018. Accessed August 14, 2019.

Heparin sodium. EBSCO Nursing Reference Center website. Available at:  https://www.ebscohost.com/nursing/products/nursing-reference-center . Updated September 7, 2018. Accessed August 14, 2019.

Revision Information

  • Reviewer: EBSCO Medical Review BoardJames P. Cornell, MD
  • Review Date: 08/2019
  • Update Date: 12/13/2019