Platelet factor 3 (PF3) availability

Last updated: Thursday, 25, March, 2004

Rarely performed.

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Item Process

4.5 mL blood added to 0.5 mL citrate.


Platelets are substituted for phospholipid in tests based on either the APTT or the Stypven time.


Rarely indicated in the investigation of platelet function.


PF3 is platelet membrane phospholipid which becomes available as a surface for coagulation reactions after platelet aggregation.
PF3 availability is decreased in a number of disorders of platelet function, including uraemia, but the clinical significance of this finding is uncertain.


Hardisty RM and Hutton RA. Br J Haematol 1966; 12: 764-767.

Chanarin I ed. Laboratory Haematology. Churchill Livingstone 1989.