title: Anticoagulant-dependent in vitro hemagglutination in a cat.
abstract: A 17-year-old domestic shorthaired cat was presented to the Cornell University Hospital for Animals for recheck of hyperthyroidism previously treated with radioiodine. Marked agglutination was noted in a blood sample collected into EDTA for a CBC; no other clinical or hematologic evidence of hemolysis was observed and none developed despite persistent agglutination in additional EDTA samples collected over a 2-month period. Blood drawn into heparin and sodium citrate tubes did not have grossly or microscopically detectable agglutination, unless EDTA was added. Plasma from the cat induced agglutination of washed RBCs from a control cat in the presence of EDTA but not in the presence of heparin. Flow cytometric analysis of samples created by mixing plasma from the patient with washed RBCs from a control cat showed immunoglobulin coating of the control RBCs, predominantly by IgM. These findings suggested an anticoagulant-dependent antibody-mediated mechanism for the agglutination. EDTA-dependent hemagglutination has not been reported previously in cats, although rare cases have been described in humans. The phenomenon needs to be recognized as an in vitro occurrence in order to prevent erroneous diagnosis of immune-mediated hemolytic anemia.
authors.affiliation: Departments of Population Medicine and Diagnostic Sciences, Cornell University College of Veterinary Medicine, Ithaca, NY 14853, USA. dms279@cornell.edu
authors.forename: Deanna M W
authors.initials: DM
authors.lastname: Schaefer
authors.forename: Heather
authors.initials: H
authors.lastname: Priest
authors.forename: Tracy
authors.initials: T
authors.lastname: Stokol
authors.forename: Richard E
authors.initials: RE
authors.lastname: Goldstein
authors.forename: Nicole
authors.initials: N
authors.lastname: Belcher
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000737:chemistry*; D002415:Cats / Q000097:blood*; D002614:Chelating Agents / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry*; D005260:Female; D006386:Hemagglutination Tests / Q000662:veterinary*; D006493:Heparin / Q000737:chemistry*
chemical_list: D000925:Anticoagulants; D002614:Chelating Agents; D006493:Heparin; D004492:Edetic Acid