What is a Platelet Assay?

A platelet assay is a test which is designed to measure an aspect of platelet function. Also known as a platelet function test, a platelet assay can include a single function test, or multiple tests. The goal of such testing is to learn more about a condition which may involve malfunction of the platelets. Turnaround times on a platelet assay vary, depending on the lab, and rush orders can be placed if results are needed right away although this will add to the cost of the test. Some facilities have their own labs and are able to conduct a platelet assay very quickly.

In order to perform a platelet assay, a sample of blood must be taken. This procedure can be done in a clinic or doctor's office, and is uncomfortable, but rarely painful. Several vials of blood may be collected so that a number of different tests can be run on the blood, and to avoid calling the patient back in for another blood draw by taking extra blood for the lab.

One aspect of a platelet assay can be a platelet count, in which the lab determines how many platelets are present, and at what stage of their life cycle they are in. Abnormally high or low counts can explain problems with clotting. If platelets are low, the blood has difficulty clotting, and if they are high, the blood may be prone to excessive clotting. An assay can also include a test to see how long it takes for a patient's blood to clot.

A platelet assay can include tests such as an aggregation function test, in which the lab determines whether or not platelets are sticking together like they are supposed to. Tests can also explore adherence, expression of various clotting factors, and tolerance to aspirin. In this case, blood may be drawn from a patient before and after aspirin administration to see how the platelets respond, with the goal of seeing if aspirin is helping with a clotting problem.

The results of a platelet assay are usually printed with normal ranges and values so that a doctor can determine at a glance if anything is abnormal. A lab technician may also make notes on the test results if anything unusual is observed during the platelet assay. Using this information, a doctor can fit together the pieces of a diagnostic puzzle to find out why someone is sick, monitor an ongoing condition, or determine whether or not a patient is a suitable candidate for surgery.