Platelet aggregometry

Keywords: Platelet function studies, PLT function studies

Specimen:

Citrated blood; generally requires prior arrangement with laboratory.

Ideally the patient should not have taken aspirin or other NSAID or drug/compound affecting platelet function in the week prior to testing.

Method:

Platelet-rich plasma stirred at 37°C with continuous recording of light transmission. Aggregating agent (agonist) added; aggregation results in decreasing optical density.

The platelet release reaction is assessed by the presence of secondary aggregation with ADP, adrenaline; aggregation with collagen, arachidonate.

The release reaction can be measured by prior incubation of platelet-rich plasma with labelled serotonin, and measurement of radioactivity in supernatant plasma following aggregation or using other reagents.

Application:

Platelet function is predictably abnormal after ingestion of aspirin and other NSAIDs and in patients with uraemia.

Platelet function may be abnormal in patients with Myeloproliferative neoplasms, Myelodysplastic syndromes and in Paraproteinaemia. 

Interpretation:

Pattern of aggregation and presence or absence of 'primary' or 'secondary' waves help to define various platelet functional disorders. 

Reference:

Bain et al. Dacie and Lewis Practical Haematology. 11th Ed. 2012.

Hutton R.A. et al. J Clin Pathol. 1989; 42: 858-864.