Specifications
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RDW (Red Cell Distribution Width)
The red cell distribution width is a function of the RBC count and derived from
the RBC histogram. In most cases, any error introduced in the MCV may also
cause the RDW to be erroneous. Especially blood transfusions may raise the
RDW significantly due to the presence of bi-modal populations.
PLT (Platelets or Thrombocytes)
Very small RBCs might elevate a PLT count. This effect is minimized in the in-
strument due to the use of a floating threshold (discriminator). By observing the
PLT and RBC histograms, this effect is seen as an overlapping PLT/RBC area.
Agglutinated RBCs
Agglutinated RBCs might trap platelets and may give an erroneous low PLT
count. The presence of agglutinated RBCs is detected by monitoring the MCHC
parameter and by careful examination of the stained blood film.
Giant platelets in excessive numbers
This may cause a low PLT count since they might fall within the RBC threshold
range.
Chemotherapy
Cytotoxic and immunosuppressive drugs may increase the fragility of these cells,
which may cause low PLT counts. Reference (manual) methods may be necessary
to obtain an accurate platelet count.
Hemolyzis
Hemolyzed specimens contain red cell stroma, which may elevate platelet counts.
A.C.D. blood
Blood anti coagulated with Acid Citrate Dextrose may contain platelet aggre-
gates, which could depress the platelet count.
RBC inclusions
Erythrocyte inclusions may also produce a spuriously increased platelet count.
(e.g. Howell-Jolly bodies, siderotic and basophilic granules)
Platelet agglutination
Clumped platelets due to poor collection techniques or platelet satellitosis caused
by EDTA activation of immunoglobulins may cause a decreased platelet count
and/or an elevated WBC count. The specimen should be recollected in sodium
citrate anticoagulant and re analyzed for only the platelet count. The final PLT
result must be corrected for the sodium citrate dilution effect.
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