Last Updated on October 18, 2025 by Analgesia team
Platelets in Blood In Medical
Platelets are tiny, disc-shaped cells in the blood that help stop bleeding and form clots. They are also known as thrombocytes.
How platelets work
Platelets are tiny, colourless cells in the blood that play a vital role in clotting and stopping bleeding. When a blood vessel is damaged, the body sends chemical signals that attract platelets to the injury site. Once they arrive, platelets clump together to form a sticky clot, sealing the break and preventing further blood loss.
Platelets are also remarkably versatile—they can extend small projections or “tentacles” to reach the broken vessel walls, helping them attach securely. In addition to clot formation, platelets release growth factors that support tissue repair and healing at the injury site. Without enough platelets, even minor cuts or injuries can lead to prolonged bleeding or bruising.
Platelet levels
A normal platelet count in adults typically ranges from 150,000 to 450,000 platelets per microliter of blood. This level is usually measured during a routine blood test called a complete blood count (CBC). Regular monitoring of platelet levels can help detect underlying health issues and ensure the blood can clot properly when needed.
Low Platelet Count
A low platelet count, known medically as thrombocytopenia, occurs when the number of platelets falls below 150,000 per microliter. People with thrombocytopenia may find it harder to stop bleeding, and even minor injuries can result in excessive bruising or prolonged bleeding.
Thrombocytopenia can be caused by a variety of factors, including bone marrow disorders, certain cancers, or cancer treatments such as chemotherapy. In severe cases, a very low platelet count can become a medical emergency, requiring urgent treatment to prevent dangerous internal bleeding
High platelet count
A high platelet count, medically known as thrombocytosis, occurs when the number of platelets in the blood rises above 450,000 per microliter. While platelets are essential for clotting, having too many can be dangerous because it increases the risk of forming blood clots, which may lead to stroke, heart attack, or deep vein thrombosis.
Interestingly, high platelet counts can also cause bleeding problems, such as frequent nosebleeds, gum bleeding, or easy bruising, because the platelets may not function normally despite being elevated in number.
Several factors can trigger thrombocytosis. It can be a reactive response to stress on the body, including surgery, infections, or inflammation. In some cases, it may be caused by bone marrow disorders where the body produces too many platelets without an obvious trigger.
Monitoring platelet levels through a complete blood count (CBC) is important, as untreated thrombocytosis can increase the risk of serious complications. Treatment depends on the cause and may involve medication to lower platelet count or address the underlying condition.
Platelet transfusions
A platelet transfusion is a procedure that involves transfusing a concentration of platelets into a patient’s body to treat or prevent bleeding.
-
- To treat or prevent bleeding in people with low platelet counts or poor platelet function
- To help people who have lost a lot of blood after surgery, an accident, or an organ transplant
- To treat people with cancer, especially those undergoing chemotherapy
Checking platelet levels
A complete blood count (CBC) is a routine blood test that measures the number of platelets in your blood.