Changes in automated complete blood cell count and differential leukocyte count results induced by storage of blood at room temperature

To delineate changes that occur in various parameters of automated complete blood cell count (CBC) and differential leukocyte count (differential) on prolonged storage of blood at room temperature. A CBC and an automated differential were performed on the Coulter Gen.S on 40 K(3) (tripotassium ethylenediamine-tetraacetate) EDTA-anticoagulated blood specimens once daily, specimen volume permitting, for 3 to 7 days. Specimens were kept at room temperature throughout the study. The results were tabulated using a personal computer with Excel software. Percent change or absolute difference from the initial value for each parameter for each subsequent day of the study period was calculated. Among the CBC parameters, hemoglobin, red blood cell count, and mean corpuscular hemoglobin were stable for the duration of the study (7 days), white blood cell count was stable for at least 3 days (up to 7 days, if the count was within or above the normal range), and platelet count was stable for at least 4 days (up to 7 days, if the count was within or above the normal range). The mean corpuscular volume, mean platelet volume, hematocrit, and red blood cell distribution width each increased, and the mean corpuscular hemoglobin concentration decreased from day 2 onward. Among the differential parameters, the relative percentages and absolute numbers of neutrophils, lymphocytes, and eosinophils tended to increase, whereas those of monocytes trended downward over time. Limited data on basophils did not reveal an appreciable change. Blood specimens stored at room temperature for more than 1 day (up to 3 days or possibly longer) were found to be acceptable with some limitations for CBC but not for the differential.