Effects of Storage of Blood at Room Temperature on Hematologic Parameters Measured on Sysmex XE2100 (original) (raw)

Clinical laboratories equipped with modern automated analyzers are capable of processing large volumes of hematologic tests in an efficient and timely manner. These tests include complete blood count (CBC), differential leukocyte count (diff), reticulocyte count (retic), and more recently, the nucleated red blood cell count (NRBC). To ensure reliability of the results generated by the instrument, it is imperative that the specimens are collected appropriately in a suitable anticoagulant and analyzed on a properly calibrated instrument within the time frame considered appropriate or recommended by the manufacturer. Dipotassium ethylenediamine-tetraacetate (K 2-EDTA)-anticoagulated blood is the specimen of choice for all of these tests. Generally, specimens arrive in the laboratory and are analyzed within hours of collection from patients. However, it is not uncommon for laboratories to receive specimens that are 1 to 3 days old. Furthermore, it is a common practice to keep these specimens at room temperature until delivery to the laboratory and processing. Will these older specimens generate clinically reliable results when processed through the automated analyzer for any or all of the hematologic tests cited above? Manufacturers of automated analyzers and published literature usually cite that blood specimens kept at room temperature for 24 hours to 48 hours generally yield reliable results. 1-5 However, specific information concerning the suitability or unsuitability of specimens older than 1 or 2 days for various automated hematologic tests is limited, particularly in the recent literature. The only recent publication, from our own group 3 years ago, reported on changes in automated CBC and diff induced by storage of blood at room temperature. 6 In that study, the Beckman Coulter GenS was used to perform the CBC and diff. The retic count was not included in the study and the automated NRBC count was not available on that analyzer. For the past 2 years, our laboratory has been using XE-2100, an automated analyzer from Sysmex America, Mundelein, IL, for performing automated CBC, diff, retic and NRBC. The purpose of the present study was to delineate changes that occur in various parameters of all tests, including retic and NRBC, performed on Sysmex XE-2100, during storage of blood at room temperature. Material and Methods A total of 40 K 2-EDTA-anticoagulated blood specimens were selected from the routine laboratory workload over several days to represent a range of normal and abnormal values (Table 1). Among the 40 specimens, 12 were leukopenic (white cell count <4.0 x 10 3 /µL), 10 had leukocytosis (white cell count >11.0 x 10 3 /µL), 13 were thrombocytopenic (platelet count <140 x 10 3 /µL), and 6 had thrombocytosis (platelet count >400 x 10 3 /µL). All but 9 were anemic, with hemoglobin values less than 12.5 g/dL. Specimens were kept at room temperature throughout the study. Each specimen was run on 1 of the 2 Sysmex XE-2100 analyzers in our laboratory for CBC, diff, retic, and NRBC once daily for 5 days. To determine within-day precision, 25 of the 40 specimens, representing a range of normal and abnormal values (Table 2), were analyzed a second time, within 8 hours of the initial run, on either the same or a different XE-2100 analyzer. The XE-2100 utilizes impedance technology for red cell count and platelet count, light scattering technology for the white cell count, and a photocolorimetric