ANEMIA

• Anemia


  Decrease in hemoglobin concentration or number of red blood cells (RBCs) resulting in decreased oxygen delivery to tissue, causing tissue hypoxia
• Anemia is a common condition affecting an estimated 1.93 billion people worldwide
• Anemia


  Not a disease but rather a manifestation of an underlying condition or deficiency
• Functional definition of anemia

  Decrease in the oxygen-carrying capacity of the blood, can be caused by insufficient hemoglobin or impaired hemoglobin function
• Operational definition of anemia

  Reduction in the hemoglobin content of blood that can be caused by a decrease in the RBC count, hemoglobin concentration, and hematocrit below the reference interval for healthy individuals of similar age, sex, and race, under similar environmental conditions
• Reference intervals for hemoglobin, RBC count, and hematocrit are different for individuals of different sex, age, and race
• Each laboratory must determine its own reference intervals based on its particular instrumentation, methods used, and the demographic characteristics and environment of its patient population
• Patient is considered anemic


  If the hemoglobin value falls to less than those listed on the inside cover
• Importance of patient history and clinical findings

  • Obtaining a detailed history to elicit potential causes of anemia
  • Evaluating physical examination findings to provide clues to hematologic disorders
• Pica


  Cravings for unusual substances such as ice (pagophagia), cornstarch, or clay, associated with iron deficiency anemia
• Asymptomatic anemia


  Can occur in mild or slowly progressive anemias where the body is able to adapt
• Physical examination findings in anemia

  • Skin (for petechiae), eyes (for pallor, jaundice, and hemorrhage), mouth (for mucosal bleeding)
  • Sternal tenderness, lymphadenopathy, cardiac murmurs or arrhythmias, splenomegaly, and hepatomegaly
  • Jaundice, which may indicate increased RBC destruction and a hemolytic component to the anemia
  • Vital signs (tachycardia in rapid fall in hemoglobin, normal heart rate in long-standing anemia)
• Moderate anemia


  Hemoglobin concentration of 7 to 10 g/dL, may cause pallor but may not produce clinical symptoms if onset is slow
• Severe anemia


  Hemoglobin concentration of less than 7 g/dL, usually produces tachycardia, hypotension, and other symptoms of volume loss
• Physiologic adaptations in anemia

  • Acute blood loss: Sympathetic overdrive, preferential shunting of blood to vital organs, increase in RBC 2,3-bisphosphoglycerate to increase oxygen delivery
  • Slowly developing anemia: Increase in erythropoietin production to stimulate erythropoiesis and release more RBCs
• Erythropoiesis


  The term used for marrow erythroid proliferative activity, under the control of erythropoietin and other growth factors/cytokines
• Ineffective erythropoiesis


  Production of defective erythroid precursor cells that undergo apoptosis in the bone marrow before maturing, seen in conditions like megaloblastic anemia, thalassemia, and sideroblastic anemia
• Insufficient erythropoiesis


  Decrease in the number of erythroid precursors in the bone marrow, resulting in decreased RBC production, can be due to deficiencies (iron, erythropoietin) or loss/suppression of precursors
• Blood loss and hemolysis

  Acute blood loss or chronic blood loss can lead to anemia, as can increased hemolysis resulting in shortened RBC lifespan
• Anemia


  Can develop as a result of acute blood loss (such as a traumatic injury) or chronic blood loss (such as an intermittently bleeding colonic polyp)
• Anemia


  Can develop due to increased hemolysis resulting in a shortened RBC life span
• With acute blood loss and excessive hemolysis, the bone marrow takes a few days to increase production of RBCs
• Numerous causes of hemolysis exist, including intrinsic defects in the RBC membrane, enzyme systems, or hemoglobin, or extrinsic causes such as antibody-mediated processes, mechanical fragmentation, or infection-related destruction
• Complete Blood Count (CBC)


  Used to detect the presence of anemia by determining the RBC count, hemoglobin concentration, hematocrit, RBC indices, white blood cell count, and platelet count
• RBC indices


  Include the mean cell volume (MCV), mean cell hemoglobin (MCH), and mean cell hemoglobin concentration (MCHC)
• MCV


  Measure of the average RBC volume in femtoliters (fL)
• RDW


  Index of variation of cell volume in an RBC population
• Reticulocyte count


  Assesses the bone marrow's ability to increase RBC production in response to an anemia
• Reticulocytes


  Young RBCs that lack a nucleus but still contain residual ribonucleic acid (RNA) to complete the production of hemoglobin
• Absolute reticulocyte count


  Determined by multiplying the percent reticulocytes by the RBC count
• Corrected reticulocyte count


  Obtained by multiplying the reticulocyte percentage by the patient's hematocrit and dividing the result by 45 (the average normal hematocrit)
• Reticulocyte production index (RPI)


  A better indication of the rate of RBC production than the corrected reticulocyte count
• Immature reticulocyte fraction (IRF)


  The fraction of immature reticulocytes among the total circulating reticulocytes, helpful in assessing early bone marrow response after treatment for anemia
• Peripheral blood film examination


  An important component in the evaluation of an anemia, with particular attention to RBC diameter, shape, color, and inclusions
• RBC abnormalities


  • Anisocytosis
  • Macrocyte
  • Oval macrocyte
  • Microcyte
  • Poikilocytosis
  • Spherocyte
  • Elliptocyte, ovalocyte
  • Stomatocyte
  • Sickle cell
  • Hb C crystal
  • Hb SC crystal
  • Target cell (codocyte)
  • Schistocyte (schizocyte)
  • Helmet cell (keratocyte)
  • Folded cell
  • Acanthocyte (spur cell)
  • Burr cell (echinocyte)
  • Teardrop cell (dacryocyte)
• Erythrocyte inclusions


  • Diffuse basophilia
  • Basophilic stippling
  • Howell-Jolly body
• Commonly Associated Disease States

  • Uremia
  • Pyruvate kinase deficiency
  • Primary myelofibrosis
  • Myelophthisic anemia
  • Thalassemia
  • Megaloblastic anemia
• Such as thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, disseminated intravascular coagulation
• Such as traumatic cardiac hemolysis
• Cells with similar morphology that are unevenly distributed in a blood film (not present in all fields) likely are due to a drying artifact in blood film preparation; these artifacts are sometimes called crenated RBCs