Platelet Function Analyzed by Light Transmission Aggregometry.

Analysis of platelet function is widely used for diagnostic work-up in patients with increased bleeding tendency. During the last decades, platelet function testing has also been introduced for evaluation of antiplatelet therapy, but this is still recommended for research purposes only. Platelet function can also be assessed for hyper-aggregability, but this is less often evaluated. Light transmission aggregometry (LTA) was introduced in the early 1960s and has since been considered the gold standard. This optical detection system is based on changes in turbidity measured as a change in light transmission, which is proportional to the extent of platelet aggregation induced by addition of an agonist. LTA is a flexible method, as different agonists can be used in varying concentrations, but performance of the test requires large blood volumes and experienced laboratory technicians as well as specialized personal to interpret results. In the present chapter, a protocol for LTA is described including all steps from pre-analytical preparation to interpretation of results.