title: Pseudothrombocytopenia or platelet clumping as a possible cause of low platelet count in patients with viral infection: a case series from single institution focusing on hepatitis A virus infection.
abstract: BACKGROUND
  Pseudothrombocytopenia (PTCP) is the phenomenon of ethylenediaminetetraacetic acid anticoagulant-activated platelet clumping, which results in artificially low platelet counts. Other investigators have reported a few cases of PTCP associated with viral infections. The objective of this study was to demonstrate the association of viral infection with PTCP.
  
  
  METHODS
  Medical records of patients with thrombocytopenia who were tested for peripheral blood smear examination between March 2009 and February 2011 were reviewed for platelet clumping and viral infection.
  
  
  RESULTS
  Thrombocytopenic patients with viral infection had a higher frequency of platelet clumping than those with other diseases, which was statistically significant (13.8% vs. 6.5%, respectively: P = 0.003). Among the 18 cases where PTCP or platelet clumping was related to viral infection, hepatitis A virus infection (72.2%) was most common, followed by cytomegalovirus (11.1%) and influenza A H1N1 infections (5.6%). A third (33.3%) of the patients had platelet counts <100 × 10⁹/L.
  
  
  CONCLUSIONS
  Pseudothrombocytopenia or platelet clumping should be considered in patients with acute viral infection, particularly if the platelet count is unexpectedly low, because failure to recognize PTCP may lead to unnecessary diagnostic tests and patient mismanagement.
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, South Korea.
authors.forename: W-H
authors.initials: WH
authors.lastname: Choe
authors.forename: Y-U
authors.initials: YU
authors.lastname: Cho
authors.forename: J-D
authors.initials: JD
authors.lastname: Chae
authors.forename: S-H
authors.initials: SH
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000494:pharmacology; D002118:Calcium / Q000737:chemistry; D002614:Chelating Agents / Q000494:pharmacology; D002675:Child, Preschool; D003586:Cytomegalovirus Infections / Q000097:blood / Q000503:physiopathology / Q000821:virology; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D006506:Hepatitis A / Q000097:blood / Q000503:physiopathology* / Q000821:virology; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification; D007251:Influenza, Human / Q000097:blood / Q000503:physiopathology / Q000821:virology; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010976:Platelet Count; D012720:Severity of Illness Index; D013921:Thrombocytopenia / Q000209:etiology* / Q000503:physiopathology; D055815:Young Adult
chemical_list: D000925:Anticoagulants; D002614:Chelating Agents; D004492:Edetic Acid; D002118:Calcium