Pseudothrombocytopenia -- a caveat.
Pseudothrombocytopenia is an ex vivo thrombocytopenia, counted by an automated cell counter, but not configured by microscopic examination of a well prepared blood smear. Incidences of pseudothrombocytopenia reported in different studies range from 0.09-0.21%, which could account for 15-30% of all cases of thrombocytopenla. Failure to identify pseudothrombocytopenia has led to a lot of clinical problems like unnecessary platelet transfusion, glucocorticoid therapy and so on. Haematological cell counters count platelets as particles with volume between 2 and 20fl. Thus platelet clumps are counted as leucocytes while fragmented RBCs as platelets. This study found pseudothrombocytopenia due to causes like EDTA blood stored at less than 32 degrees C for more than 2 hours (35%), excess EDTA in sample (10.7%), hyperlipidaemia, auto-immune disease, pregnancy, etc. No apparent cause could be found in 52% of cases. Hence it is emphasised that direct microscopic examination of a well stained blood smear from EDTA-venous blood (within 1hour) and or direct counting under Neubauer chamber with 1% ammonium oxalate (in special cases) is almost mandatory before releasing a report of platelet count. Also factors related to ratio and storage of EDTA-blood, calibration of instruments, proper selection of reagents, supervision of laboratory staff are essential to rule out any error of report including pseudothrombocytopenia.
Department of Pathology, Medical College, Kolkata 700073.
S K
SK
Sinha
Palash Kumar
PK
Mandal
Jayati
J
Mallick
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001800:Blood Specimen Collection; D002648:Child; D002675:Child, Preschool; D003951:Diagnostic Errors; D004492:Edetic Acid; D006801:Humans; D008875:Middle Aged; D010976:Platelet Count; D013921:Thrombocytopenia / Q000175:diagnosis*; D055815:Young Adult
D004492:Edetic Acid