What Causes Giant Platelet Disorder?

Medically Reviewed on 12/7/2022
Giant Platelet Disorder
Giant platelets fail to stick together and form adequate clots, resulting in severe bleeding when injured.

Giant platelets, also known as macrothrombocytopenia, are a rare blood disorder characterized by large-sized platelets and an increased risk of bleeding. Platelets in patients with chronic myelogenous leukemia are abnormally large and heterogeneous.

Giant platelet disorder is a condition that is genetically inherited with faulty genes, such as GP1BA, GP1BB, and GP9. The gene responsible for the syndrome is mapped with the short arm of chromosome 17. If both parents have faulty genes for the condition, the child will be born with a giant platelet disorder. Changes in the genes are caused by the deficiency of proteins in platelets called glycoproteins.

What is giant platelet disorder?

Giant cell platelet disorder refers to a condition in which a person has abnormally large platelets and thrombocytopenia and an increased tendency to bleed. Giant platelets fail to stick together and cannot form adequate clots, resulting in severe bleeding when injured. A large platelet has a diameter greater than 4 µm, whereas a giant platelet has a diameter greater than 7 µm. The larger the size of the platelets, the lesser the platelet count, which results in bleeding disorders

Conditions that have giant platelets include:

  • Myeloproliferative neoplasms: These are rare blood cancers that are caused by mutations in stem cells in the bone marrow. The mutations cause excess production of any combination of white blood cells, red blood cells, and platelets.
  • Myelodysplasia: Rare blood cancer in which the blood cells in the bone marrow fail to mature into healthy blood cells.
  • Bernard-Soulier syndrome: Is associated with large-sized platelets and decreased platelet count. The combination is called macrothrombocytopenia. People with Bernard-Soulier syndrome are at an increased risk of bruising and bleeding (more severely than usual). Sometimes, the condition causes tiny red spots on the skin called petechiae. Women with Bernard-Soulier syndrome have heavy or prolonged bleeding during their menstrual periods, known as menorrhagia. Bernard-Soulier syndrome is a rare disorder that affects one in a million people.


Sickle cell disease is named after a farming tool. See Answer

What are the symptoms of giant platelet disorder?

Symptoms of giant platelet disorder include:

  • Nosebleeds
  • Gum bleeding
  • Spontaneous bleeding without any trauma
  • Severe bleeding even after a minor injury
  • Heavy and prolonged menstrual bleeding
  • Petechiae

How to diagnose giant platelet disorder

Giant platelet disorders can be diagnosed using various tests, such as:

  • Complete blood count tests, which help ascertain the platelet count and confirm the diagnosis.
  • Platelet function tests, which include:
    • Closure time, which determines the time taken to form a clot.
    • Viscoelastometry, which confirms the strength of the blood clot.
    • Platelet aggregometry, which helps find how well the platelets help to form a clot.
    • Lumiaggregometry, which helps identify abnormal platelets.
    • Bleeding time, which is used to determine various platelet disorders. It helps determine the time taken to stop bleeding after a minor cut.
  • Glycoprotein tests, which help determine abnormal clot formation.
  • The peripheral smear test, which is used to detect abnormalities in red blood cells, white blood cells, and platelets.
  • Blood clotting test, which is done to evaluate clotting time.

How to treat giant platelet disorder

There is no treatment for giant platelet disorder, but the symptoms can be treated.

The treatment options, which mainly include steroids and intravenous gamma globulin, are as follows:

  • Steroids: Help increase the number of platelets in two to three weeks, but they may have side effects such as irritability, stomach irritation, increased blood pressure, acne, and weight gain.
  • Medication changes: If the condition is suspected to be caused, a change in medication or discontinuation of the medicine is required. Avoid medicines such as antiplatelet medications.
  • Platelet transfusion: This may be necessary in case of severe bleeding either due to surgery or major trauma.
  • Lifestyle changes: Include avoiding sports that may increase the risk of injuries.
  • Medications: Drugs such as romiplostim and Promacta (eltrombopag) are recently approved to treat thrombocytopenia.
Medically Reviewed on 12/7/2022
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