Platelets function:These assays determine the number of coated beads or platelets that aggregate after substances are added to activate platelets. They provide a single measure of aggregation in platelets normal range
(an endpoint) rather than a measure of aggregation over time. More platelets aggregating or sticking to beads indicates better platelet function. These tests may be abnormal if the platelet count is low, if platelet function is reduced, or if anti-platelets medications are present.
BLEEDING TIME In platelets
In the past, the primary screen for platelet dysfunction was the bleeding time-a test that involved making two small, shallow, standardized cuts on the inner forearm and measuring the amount of time that they tool to stop bleeding. The bleeding time procedure has fallen from favor in recent years.
Many hospitals are no longer offering it, and several national organizations have issued position statements against its routine use. The bleeding time is not sensitive or specific, and it does not necessarily reflect the risk or severity of surgical bleeding. It is poorly reproducible, can be affected by aspirin ingestion and by the skill of the person performing the test, and frequently leaves small thin scars on the forearm.
Many different substances can activate a platelet, including proteins in the wound, factors released from other activated platelets, and factors produced by the coagulation system that aids platelets in forming a strong plug to stop bleeding. Many different platelet abnormalities have been described due to problems with one or more of these activating systems. Platelet aggregation testing can diagnose a variety of inherited and acquired platelet function disorders. It is typically performed at academic medical centers or large hospitals due to the complexity of the testing and interpretation.