If patients have repeated full blood counts which describe platelet clumping, ‘no platelet count’ will be reported. Platelet clumping can lead to falsely low automated platelet counts.
Platelet clumping can occur due to platelet activation while samples are being taken (difficult venepuncture), or, in some patients, due to antibodies which react with the EDTA within the FBC tubes causing platelet aggregation.
‘Thromboexact’ blood tubes can be request from all haematology laboratories within Lothian and contain no EDTA avoiding aggregation. Thromboexact tubes only provide a platelet count.
Please initially repeat sample in the normal way, but if there is ongoing clumping:
- Request Thromboexact tube from haematology labs – SJH/RIE/WGH
- Send a FBC sample (EDTA) and Thromboexact tube so a complete FBC can be issued.
- A paper form will need to be sent stating platelet clumping in the clinical details, the FBC and Thromboexact tube will need to be sent together with this paper request (TRAK and ICE requesting will be available in the future).
If thrombocytopenia persists when no clumping is reported, please refer to the RefHelp thrombocytopenia guidance.
C.M & A.C 13-12-23
