Platelet Aggregation Study
Haematology Overview / Directory
Purpose of the test
Platelet function studies may be performed if a patient has a bleeding disorder with a normal or relatively normal coagulation screen and platelet count. Typically the type of bleeding will be 'mucosal' i.e. nose bleeds, bruising, menorrhagia.
Platelet clumping can be induced by the addition of various aggregation agents (agonists) to platelet rich plasma (PRP). A platelet aggregometer is used to measure the changes in light transmission through PRP upon the addition of the agonist. Light transmission will increase as the platelets aggregate. The responses of patient plasma are compared to those of a normal control. Information about percentage aggregation over time, slope analysis and slope shape with particular agonists can contribute to diagnosis of platelet function disorder.
Reference Range
The normal control must demonstrate a normal response to the agonists used
Sample Requirements
Four x 5 ml coagulation citrated tubes. The blood must be obtained by clean venepuncture with minimal arm stasis. There must be no clots or haemolysis. The tubes must be mixed gently.
Storage and Transport
An appointment must be booked with the Haemostasis laboratory in advance.
The samples must be delivered to the haemostasis staff immediately to ensure specimens are not high spun in error. Keep at room temperature
Turnaround Time
Printed report available within 3 hours of sample reception
Time Limit for Extra Tests
2 hours
Factors affecting results or interpretation
A detailed patient history is required for accurate test interpretation.
A number of prescription and non-prescription drugs may interfere with platelet aggregation. Substances such as tobacco and alcohol may also affect test results.
Platelet count must not be less than 100,000 platelets/uL
Contacts
Haemostasis Laboratory on 020 3299 9000 ext 2434 e-mail: liz.ford@nhs.net
