Spurious, marked leukocytosis in 2 cats with Heinz body hemolytic anemia

Two domestic shorthair cats were presented with anorexia and dehydration following ingestion of caramelized onions. Shared key findings from a CBC (ADVIA 2120), serum biochemistry, and urinalysis included a spurious, marked leukocytosis with discordant basophil (BASO) channel and peroxidase channel WBC counts, normal manual leukocyte counts, mild, non-regenerative anemia with discrepancies between automated and manual reticulocyte counts, an abundance of large Heinz bodies (HBs), and highly irregular scattergrams. Case 1 also demonstrated a markedly elevated mean corpuscular hemoglobin concentration (MCHC) and discrepancies between RBC hemoglobin indices. Spurious leukocyte results were confirmed through re-analysis of samples (including the acquisition of a new sample, use of an alternate analyzer (Sysmex XT-2000iV; Case 1 only), and evaluation of scattergrams and blood films (Cases 1 and 2). Repeatedly discrepant reticulocyte counts were also identified. In both cases, the erroneous BASO WBC counts, discrepancies in reticulocyte counts and RBC indices, and atypical scattergrams were interpreted to result from various effects of the HBs. These cases emphasize the importance of reviewing blood films, interpreting scattergrams, and the usefulness of duplicate methods for determining various measurands on hematology analyzers.