**1.3 Technology at a glance**

The Hemogram is one of the more required tests by the clinicians; the analysis nowadays is totally automated and the correct interpretation of the results requires to unite the knowledge about the characteristics of the equipment and the clinical meaning of the results. The suppliers contribute innovations, providing new parameters that can help the clinicians to make a diagnosis in a fast, cheap and useful manner (Buttarello & Plebani, 2008).

The professionals of the Clinical Laboratory must obtain the maximum yield of the new technologies obtaining as much information as possible.

Automated blood cell counters have changed substantially during the last 20 years. Technological progress has meant that in recent years modern analyzers, fully automated, have been available. These analyzers report new parameters that provide further information from the traditional count; this information must be evaluated to prove the potential clinical utility in different clinical situations.

When a state of iron deficiency proceeds red blood cells are continuously produced in the bone marrow and as the iron stores progressively decrease, mean cell volume (MCV), mean cell hemoglobin (MCH) and red blood cell count (RBC) count tend to decline. In iron deficient erythropoiesis, synthesis of hemoglobin (Hb) molecules is severely impaired leading to the production of erythrocytes with low Hb concentration (hypochromic cells). Because of their long life span of approximately 3 months, several cohorts of normochromic and increasingly hypochromic red cells coexist in the peripheral blood leading to anisocytosis; red cell distribution width (RDW) reflects the variation of size of the red cells.

Flow cytometry provides information about individual cell characteristics. This is in contrast to previous measurements of MCV, MCH, and MCHC which only calculate mean indices for the total red cell population.

MCV is the mean of the volumes of all erythrocytes; RDW refers to the variety of volumes present in the red cell population, so the whole picture is clear and the contribution of marginal sized subpopulations to the calculated mean value can be assessed.

This is not the case for MHC. MCH is calculated from red blood cell count and hemoglobin and represents the average; the percentage subsets of erythrocytes can give complementary information of the contribution of cell with extreme values (hypochromic and hyperchromic cells) to the mean values, reflecting the fluctuations of iron availability to the erythron in the previous weeks.

Modern counters provide information about the reticulocyte counts but also about the characteristics of these cells (size or hemoglobin content) related to the quality of the erythropoiesis.

Nevertheless, each Company applies the technology in a different way in the analyzers, with different algorithms to translate the electronic signals to graphs and numerical values. For this reason these new parameters are exclusive of each manufacturer and they are patented.
