[...]... CHAPTER 1 TABLE 1- 1 5 PRINCIPLES OF ANEMIA EVALUATION RED CELL MEAN VALUES AT VARIOUS AGES Age Erythrocyte Count (× 10 −6 /μL) Hemoglobin (g/dL) Mean Corpuscular Volume (fl) Hematocrit (%) 1 day 5.6 21. 2 10 6 56 .1 1 month 4.7 15 .6 91 44.6 1 year 4.6 11 .6 77 35.2 4 years 4.7 12 .6 80 37 .1 8 years 4.7 12 .9 80 38.9 14 years and older (female) 4.8 (4.2–5.4) 13 .9 (11 .9 16 .0) 87 42 (37–47) 14 years and older... qualitative and unreliable approach was superseded over time by more quantitative methods Currently several means exist to assess anemia as listed in Table 1- 2 As noted, the gold standard is 51 Cr labeling of red cells to determine red cell mass A second and more commonly used technique is centrifugation of a blood sample, which packs the red cells by centripetal force and leaves the plasma and white cells... plasma and white cells in an upper layer as shown schematically in Figure 1- 1 .5 Erythrocytes far outnumber other blood cells and account for the vast majority of the packed cell volume White blood cells and platelets form a thin cream-colored layer at the interface between the packed red cells and the plasma called the “buffy CHAPTER 1 PRINCIPLES OF ANEMIA EVALUATION 7 The schematic shows the assessment... hemoglobin value or the red cell number is a more reliable anemia indicator since the instrument directly measures both CHAPTER 1 PRINCIPLES OF ANEMIA EVALUATION 11 The red cell number quantifies erythrocytes per microliter of blood As indicated in Table 1- 1 , normal values for an adult female range between 4.2 × 10 6 and 5.4 × 10 6 while those for a male are slightly higher Anemia lowers the red cell number, making... The mean volume of a single red cell Hb g/dL Quantity of hemoglobin in a volume of blood MCH Picograms The mean hemoglobin content of a single red cell MCHC Percentage Hemoglobin concentration within individual red cells Calculated as (Hb/HCT)× 10 0 RDW Percentage Coefficient of size variation of red cells in a sample = (Standard deviation of red cell volume mean cell volume) × 10 0 A larger value indicates... percentage of red cells is a reasonable practice as long as the number of red cells is in the normal range Anemias by definition have fewer red cells than normal Consequently, the use of a percentage of red cells to determine reticulocyte production is invalid in the very circumstance where it is most needed A normal “reticulocyte count” of 1% in the face of a hemoglobin value of 5 g/dL and 2.0 × 10 6 red cells/μL... The lost membrane reduces the surface area of the cells, creating microspherocytes that coexist with morphologically normal cells Hemoglobin is the predominant protein within erythrocytes Red cells lack nuclei, mitochondria, and other subcellular structures seen in most mammalian cells The uniform interior of these cells is altered with some anemias, producing visible inclusions Howell-Jolly bodies are... exploration ANEMIAS AND OTHER RED CELL DISORDERS This page intentionally left blank SECTION I Overview of Anemia Copyright © 2008 by The McGraw-Hill Companies, Inc Click here for terms of use This page intentionally left blank CHAPTER PRINCIPLES OF ANEMIA EVALUATION 1 ᭿ DEFINING ANEMIA 4 ᭿ DETECTING ANEMIA 5 ᭿ RETICULOCYTE COUNT 12 ᭿ PERIPHERAL BLOOD SMEAR 14 ᭿ BONE MARROW 16 ᭿ OTHER LABORATORY TESTS 18 ᭿... pack the red cells at the bottom of the vessel The plasma portion of the blood forms a clear supernatant while the packed red cells collect below A thin milky line between the two is the buffy coat consisting of platelets and white cells The hematocrit is the fraction of the entire sample comprised by packed red cells Anemia reduces the volume of packed red cells to below normal FIGURE 1 1 coat.” The... total 12 OVERVIEW OF ANEMIA SECTION I number of red cells in the circulation (millions/microliters) dwarfs the white cell population (thousands/microliters) Therefore, a small percentage of nucleated red cells in the peripheral blood can skew the white cell count tremendously A manual count of nucleated red cells allows subtraction of these cells from the WBC total, giving the “corrected” white cell . Hematocrit Age (× 10 −6 /μL) (g/dL) Volume (fl) (%) 1 day 5.6 21. 2 10 6 56 .1 1 month 4.7 15 .6 91 44.6 1 year 4.6 11 .6 77 35.2 4 years 4.7 12 .6 80 37 .1 8 years 4.7 12 .9 80 38.9 14 years and older (female). x0 y0 w1 h0" alt="" ANEMIAS AND OTHER REDCELL DISORDERS NOTICE Medicine is an ever-changing science. As new research and clinical expe- rience broaden our knowledge, changes in treatment and drug. IV: STEM CELL DYSFUNCTION 18 3 10 Pediatric Bone Marrow Failure Syndromes / 18 5 11 Acquired Bone Marrow Failure Syndromes / 19 3 12 The Myelodysplastic Syndromes / 207 SECTION V: HEMOGLOBIN DISORDERS