EDTA-Dependent Pseudothrombocytopenia:A Clinical Study

ObjectiveThis study is to study the prevalence and biochemical profiles of EDTA-dependent pseudothrombocytopenia (EDTA-PTCP) in a generally healthy population, and to investigate the proportion, kinetics and prevention of spuriously elevated white blood cell count concurrent with EDTA-PTCP.MethodsWe conducted a retrospective study on the patients with EDTA-PTCP among the subjects receiving yearly checkup, and compared 84 patients with 150 controls with respective to their baseline demographic features and biochemical profiles. We selected a total of 25 patients with EDTA-dependent PTCP, and determined the time courses of WBC count, WBC differential and platelet count in EDTA-and sodium citrate-anticoagulated blood, respectively. Blood smears were prepared to inspect the presence of platelet clumps using light microscopy. We evaluate the effect of automatic instrumental correction on the extent of spuriously elevated white blood cell count.ResultsThe prevalence of EDTA-PTCP in our cohort was 0.044%. The population over 50 years have significantly more EDTA-PTCPs than that of 50 years or less, P<0.05. There is also significantly more male than female EDTA-PTCPs among the subjects over 50 years old, P＜0.05. The levels of alanine transaminase (ALT),aspartate transaminase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LD)and uric acid (UA) were markedly increased in the EDTA-PTCP when compared with the control group, P<0.05.The proportion of SEWC was 92% in EDTA-dependent PTCP, and 73.9% of SEWCs were within the normal range. The development of SEWC was time-dependent, and neutrophils and lymphocytes were the main subpopulations involved in SEWC. Both corrected and uncorrected WBC counts at 15 minutes or later after blood collection in EDTA were significantly higher than their basal counts, respectively, P＜0.05.ConclusionIn generally healthy population, the prevalence of EDTA-PTCP is increased among males aged over 50 years. Biochemical profiles may be helpful to define high risk population for EDTA-PTCP. Proper interpretation of spuriously elevated white blood cell count is crucial to avoid clinic errors. Spuriously elevated white blood cell count develops in a time-dependent pattern, although the Coulter LH 750 only partly mitigates the extent of spuriously elevated white blood cell count, sodium citrate is able to effectively prevent spuriously elevated white blood cell count.