Dan Heidemann, MT (ASCP), Oncology Alliance, Milwaukee, WI wrote this question to Medlab-L on Tuesday, December 4. He gave me permission to post it here:
Most people have heard of spontaneous platelet clumping in EDTA, but what if they also clump in a citrate (blue top) tube? Thanks!
Dr. Mario Kyriacou provided this response also on December 4.
In regards the issue of platelet clumping in Na citrate, can I recommend collection of the specimen into acid citrate dextrose (ACD). In our experience, the incidence of platelet clumping in Na citrate remains frustratingly high. It would appear the more acidic conditions of the ACD tube lend themselves better to preventing platelet clumping to the point that we now routinely recommend this tube for these patients. The dilution factor is in the order of 15% compared to10% for the Na citrate, but this is a small price to pay for a reliable platelet count.
Ref: Manthorpe R, Kofod B, Wiik A, et al. Pseudothrombocytopenia. In vitro studies on the underlying mechanism. Scand J Haematol 1981;26:385-92.fficeffice” />