Thrombocytopenia
(Low Platelet Count)
Siamak T. Nabili, MD, MPH
Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
- What is thrombocytopenia?
- What causes thrombocytopenia?
- What are the symptoms of thrombocytopenia?
- When should I seek medical care for thrombocytopenia?
- How is thrombocytopenia diagnosed?
- How is thrombocytopenia treated?
- What are the complications of thrombocytopenia?
- Can thrombocytopenia be prevented?
- Thrombocytopenia At A Glance
- Related thrombocytopenia article:
Thrombocytopenia - on eMedicineHealth - Patient Comments: Thrombocytopenia - Describe Your Experience
- Find a local Hematologist in your town
What is thrombocytopenia?
Thrombocytopenia is a lower than normal number of platelets in the blood.
Platelets are one of the components of the blood along with white and red blood cells. Platelets play an important role in clotting and bleeding. Platelets are made in the bone marrow similar to other cells in the blood such as, white blood cells and red blood cells. Platelets originate from megakaryocytes which are large cells found in the bone marrow. The fragments of these megakaryocytes are platelets that are released into the blood stream. The circulating platelets make up about two third of the platelets that are released from the bone marrow. The other one third is typically stored (sequestered) in the spleen.
Platelets, in general, have a brief 7 to 10 days life in the blood, after which they are removed from the blood circulation. The number of platelets in the blood is referred to as the platelet count and is normally between 150,000 to 450,000 per micro liter (one millionth of a liter) of blood. Platelet counts less than 150,000 are termed thrombocytopenia. Platelet counts greater that 450,000 are called thrombocytosis.
The function of platelets is very important in the clotting system. Platelets are a part of a very complicated pathway. They circulate in the blood vessels and become activated if there is any bleeding or injury in the body. Certain chemicals are released from the injured blood vessels or other structures that signal platelets to become activated and join the other components of the system to stop the bleeding. When activated, the platelets become sticky and adhere to one another and to the blood vessel wall at the site of the injury to slow down and stop the bleeding by plugging up the damaged blood vessel or tissue (hemostasis).
It is important to note that, even though, the platelet numbers are decreased in thrombocytopenia, their function usually remains completely intact. Other disorders exist that can cause impaired platelet function despite normal platelet count.
Low platelet count in severe cases may result in spontaneous bleeding or may cause delay in the normal process of clotting. In mild thrombocytopenia, there may be no adverse effects in the clotting or bleeding pathways.
Picture of platelets and a blood clot
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