Abstract

Counting Feline Platelets Harold Tvedten, University Animal Hospital, Swedish University of Agricultural Sciences, Uppsala, Sweden Platelet aggregates in most feline EDTA blood samples and large size of feline platelets cause severe problems in counting feline platelets accurately. Optical platelet counts of the Sysmex XT-2000iV and Advia 2120 are better than impedance counting, but in order to get accurate feline platelet counts aggregation must be inhibited with prostaglandin E1. What are good reference values for feline platelet counts? Schalm 300-800 x 109/L UCD UC Davis 200-600 x 109/L UCD Killingsworth 230-680 x 109/L MSU Tvedten H1 26-470 x 109/L MSU PG E1 180-493 x 109/L SLU The answer varies with the type of method and instrument, anticoagulant used and method to determine reference values. I prefer the 26-470 x 109/L. The lower value of 26 x 109/L is not normal but came from using the laboratory's then current instrument and the clinic's method of collecting feline blood. Because of variable platelet aggregation, there was a gradual decrease in platelet numbers to the 26 x 109/L value and there was no good way to select a cutoff for the lower value. It was a good reference range for interpretation of the laboratory's results, but the value caused controversy because clinicians and even clinical pathologists wanted reference ranges to reflect "normal" values. It shows users of the laboratory that normal cats can have platelet counts as low as 26 x 109/L. We used prostaglandin E1 to prevent platelet aggregation and eliminate preanalytic error. Blood was collected into a CTAD tube (Diatube-H, Becton Dickinson, Oxford UK) into which prostaglandin E1 (100 ug in 20 ul ethanol) was immediately mixed after blood collection. The first attempt with 29 normal cats failed because I diluted the PG E1 too much. The second attempt worked with 9 normal cats. As shown in Figure 1, 5 of the 9 cats (cats 5-9) had clearly lower platelet counts in EDTA than CTAD blood with PG E1 collected at the same time. Note also that the Sysmex XT-2000iV optical platelet counts (PLT-O) were almost always greater than impedance counts (PLT-I). Reanalyzing PLT-O counts to remove large platelets showed that large platelets included in the PLT-O and not PLT-I were a main reason for the difference, but not only reason

Published in

Conference

European Society of Veterinary Clinical Pathology

SLU Authors

• Tvedten, Harold

  • Department of Clinical Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Animal and Dairy Science
Veterinary Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/18795