Color Atlas of Hematology - Practical Microscopic and Clinical ...

Procedures, Assays, and Normal Values11MCHC is determined using this formula:MCHC (g/dl) Hemoglobin concentration (g/dl)Hematocrit (l/l)Red Cell Distribution Width (RDW)Modern analyzers also record the red cell distribution width (cell volumedistribution). In normal erythrocyte morphology, this correlates with thePrice-Jones curve for the cell diameter distribution. Discrepancies areused diagnostically and indicate the presence of microspherocytes(smaller cells with lighter central pallor).Reticulocyte CountReticulocytes can be counted using flow cytometry and is based on thelight absorbed by stained aggregates of reticulocyte organelles. The dataare recorded as the number of reticulocytes per mill (‰) of the total numberof erythrocytes. Reticulocytes can, of course, be counted in a countingchamber using a microscope. While this method is not particularlylaborious, it is mostly employed in laboratories that often deal with orhave a special interest in anemia. Reticulocytes are young erythrocytesimmediately after they have extruded their nuclei: they contain, as a remainderof aggregated cell organelles, a net-like structure (hence thename “reticulocyte”) that is not discernible after the usual staining proceduresfor leukocytes, but can be observed after vital staining of cellswith brilliant cresyl blue or new methylene blue. The staining solution ismixed in an Eppendorf tube with an equal volume of EDTA blood and incubatedfor 30 minutes. After repeated mixing, a blood smear is preparedand allowed to dry. The sample is viewed using a microscope equippedwith an oil immersion lens. The ratio of reticulocytes to erythrocytes is determinedand plotted as reticulocytes per 1000 erythrocytes (per mill).Normal values are listed in Table 2, p. 12.