Stability of New Erythrocyte and Reticulocyte Parameters in Testing for Anemia on the Sysmex XN 9000

New erythrocyte and reticulocyte parameters provide improved classification of anemia and monitoring of erythropoeitic activity. Parameters available on the Sysmex XN analyzers include the percentage of microcytic red blood cells (%Micro-R), percentage of macrocytic red blood cells (%Macro-R), percentage of hypochromic red blood cells (%Hypo-He), percentage of hyperchromic red blood cells (%Hyper-He), reticulocyte hemoglobin content (Ret-He), and immature reticulocyte fraction (IRF). However, use of these parameters is limited by specimen stability.

To verify the stability of the new erythrocyte and reticulocyte parameters during prolonged storage, 20 blood specimens were analyzed on the Sysmex XN-9000 hematology analyzer. The specimens included healthy patients (60%) and patients with anemia (40%). The specimens were stored at room temperature (RT) and at 4° to 8°C. Analysis was performed after 12, 24, 48, and 72 hours of storage.

Reticulocyte parameters IRF and Ret-He were precise and stable for at least 72 hours after collection when stored at RT and 4° to 8°C. The volume-dependent parameters, %Macro-R and %Micro-R, were stable for less than 12 hours after collection at RT (mean [SD%], 6.55 [3.19%] and -20.70 [10.37%], respectively). Storage at 4° to 8°C showed a reduction in osmotic swelling. However, %Macro-R and %Micro-R were stable for less than 12 hours after collection (mean [SD%], 4.89 [2.02%] and -17.17 [8.38%], respectively). Similarly, %Hypo-He showed a mean (SD%) increase of 0.73 (4.05%) and %Hyper-He showed a decrease of -0.70 (9.72%) at less than 12 hours after storage at 4° to 8°C.

New reticulocyte parameters stored at RT and 4° to 8°C are suitable for testing on the Sysmex XN analyzer.