Autoimmune Thrombocytopenia Complicated by EDTA- and/or Citrate-Dependent Pseudothrombocytopenia

Pseudothrombocytopenia (PTCP) is a well-known phenomenon. However, confusion may occur due to unusual characteristics.

Two patients with autoimmune thrombocytopenia (ITP) and long-lasting PTCP are described. Initially, only the diagnosis of ITP was confirmed. During observation, discrepancies were recognized between clinical findings and platelet counts. Re-examination resulted in the additional diagnosis of EDTA-dependent PTCP. Subsequently, the latter diagnosis was changed to citrate-dependent PTCP in both cases. Interestingly, PTCP was observed to change again and became recognizable in citrate or heparin, and only during the first 20-30 min following phlebotomy in EDTA specimens.

The incidence of concomitant ITP with PTCP might be higher than previously reported, and PTCP may have variable dynamics and characteristics.