Platelet aggregation is the bunching of thrombocytes together. These thrombocytes are the small and cell-like structures produced in the bone marrow that aids in preventing bleeding. This clumping together occurs in response to numerous different agents, including the nucleotide adenosine diphosphate or ADP, and proteins of collagen and thrombin. Platelet aggregation is a vital step in the formation of a clot that is crucial – bleeding cannot be stopped without this process.

To conclude how sound the platelets are clumping together, a platelet aggregation test may be done. This test monitors this process using a platelet antagonist that triggers the bunching together in the individual patient’s sample of blood. The more common platelet antagionists are thrombin, ADP and ristocetin. After the addition of the antagonist to the sample of blood, a special type of machine known as an aggregometer monitors the turbidity or cloudiness of the sample. This aggregometer keeps a record of how fast the platelets clump together by measuring the increased clarity and light in the sample.