Evaluation of automated reticulocyte counts and their reliability in the presence of Howell-Jolly bodies.
An automated reticulocyte procedure using a flow cytometer and the fluorescent dye thiazole orange was evaluated for clinical use. The mean reticulocyte count on 118 hematologically healthy adults was 1.56% (standard deviation [SD] 0.54), with virtually no difference in percentage between women and men. The mean absolute values were 68.4 x 10(9)/L (SD 24.6) and 75.7 x 10(9)/L (SD 27.2), respectively. When compared with the standard microscopic technique, the automated method showed excellent correlation (r = 0.98) and greatly improved precision (coefficient of variation [CV] 4.1%) over the manual method (CV 22.8%). Preanalytic storage of blood samples at 4 degrees C for up to 48 hours did not significantly affect results, nor did varying the incubation time of diluted samples from 1/2 to 2 hours. In a group of patients with appreciable numbers of Howell-Jolly bodies, automated reticulocyte counts were spuriously elevated. The difference between the manual and automated counts on these patients approximated the percentage of Howell-Jolly bodies observed on their Wright-Giemsa stained blood smears.
Lofsness
K G
KG
Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis 55455.
Kohnke
M L
ML
Geier
N A
NA
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001331:Automation; D004908:Erythrocyte Inclusions; D005069:Evaluation Studies as Topic; D005260:Female; D005434:Flow Cytometry / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D017701:Reticulocyte Count / Q000295:instrumentation / Q000379:methods