Platelets are responsible for blood clotting and filling of damaged blood vessel walls in the body. Improper functioning or low levels of platelets can lead to abnormal bleeding, whereas the higher levels may increase the risk for thrombosis.

  Normal platelet count of a healthy person is in the range of 150,000 to 400,000 per microliter. However, platelet values may differ if the platelet count test is done in different laboratories. This is due to variable calibration of the laboratory equipment.   Normally, a test for platelet count is recommended as a standard part of a complete blood count. For example, this test is done in combination with additional blood elements, such as white and red blood cells.

  The platelet count test is recommended if a person has multiple bruises or takes abnormally long time to stop bleeding from a small wound.

  If platelet level falls under 20,000 per microliter, it may result in spontaneous bleeding. It is a serious serious condition in which an individual may bleed into their joints, their abdobinal cavity or even the brain (situation very similar to a hemorrhagic stroke). Other than this, the patients with a bone marrow disease, such as leukemia or other cancer in the bone marrow, often experience extremely prolonged bleeding due to a drastically reduced number of platelets,  a condition commonly known as thrombocytopenia.

  In certain other cases, platelets maintain their adhesion or stickiness, but as they are high in number, they tend to attach to each other. Platelet clusters form, which can get trapped within a blood vessel, and cause organ damage by stopping blood flow.