1 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE Chapter 20. Erythrocytic disorders

2 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders O Decreased RBC: anemia Increased RBC: erythrocytosis (polycythemia) O Laboratory investigation - Screening test; complete blood count (CBC) RBC count, Hb, hematocrit, RBC indices, WBC count, platelet count - Reticulocyte count (RBC synthesis), bilirubin (RBC destruction) O relative or absolute I. Introduction to Anemia 1. Definition of anemia O Anemia - Decrease in the competence of blood to carry oxygen to tissues, causing tissue hypoxia - Decrease in the normal concentration of hemoglobin or erythrocytes O absolute anemia vs relative anemia - In hypervolemia (hydremia): falsely decreased Hb/hematocrit - In hypovolemia (dehydration): falsely elevated Hb/hematocrit

3 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders 2. Cause and classification of anemia O cause Hemorrhage Increased destruction (hemolysis) Decreased production - Decrease of stem (progenitor) cell: aplastic anemia - Defect in DNA synthesis: megaloblastic anemia, pernicious anemia - Defect in Hb synthesis: iron deficiency anemia hemoglobinopathy (sickle cell anemia, thalassemia) O Classification using the RBC index - Microcytic hypochromic anemia - Normocytic normochromic anemia - Macrocytic normochromic anemia O intrinsic vs extrinsic O congenital vs acquired O intravascular vs extravascular

4 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders

5 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders O Mechanism 1) Proliferative defects O Decreased proliferation, maturation, release rate O Normocytic, normochromic O Bone marrow: hypocellular O Decreased reticulocyte O Whether all cell lineages are affected or only the RBCs are involved - Inappropriate EPO production: only the RBC -> decreased - Infiltration: pancytopenia (decrease in all blood cells) 2) Maturation defects O Disrupt the orderly process of either nuclear or cytoplasmic development - Macrocytic in nuclear defect: megaloblastic anemia - Microcytic, hypochromic in cytoplasmic defect: abnormal Hb production defective iron supply or utilization or heme synthesis, decreased globin synthesis O Bone marrow: erythroid hyperplasia - Ineffective erythropoiesis: destroyed before they can be released to the peripheral blood O Decreased reticulocyte (absolute, corrected, IRF, RPI<2) O Poikilocytosis: indicative of abnormal erythropoiesis

6 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders 3) Survival defect O By hemorrhage (loss) or hemolysis (destruction) O BM proliferation: increase -> increased reticulocyte O Blood film: polychromatophilic macrocytes (reticulocytosis) O Schistocytes (intravascular mechanical trauma) Spherocytes (extravascular RBC membrane damage) O Generally normocytic normochromic: macrocytosis (reticulocyte), microcytosis (schistocyte) O Increased serum bilirubin, decreased haptoglobin, increased methemalbumin, hemosiderinuria, hemoglobinuria, hemoglobinemia, exhaled CO, urine or fecal urobilinogen

7 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders

8 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders 3. Adaptation of anemia (1) Increased in oxygenated blood flow O Increase in respiration rate, cardiac rate/output O Decreased blood viscosity -> increase in circulation rate O Heart and brain supply: increased (2) Increase in oxygen utilization by tissue O Increase in 2,3-BPG -> ODC: right shift -> affinity for oxygen: decreased 4. Diagnosis of anemia (1) History: Sign of blood loss, Diet, Medication (2) Physical examination - Skin pallor, hypotension - Organomegaly: destruction of RBC - Jaundice: hemolytic anemia - Neurological dysfunction: pernicious anemia - Koilonychia (spoon-shaped nail): iron deficiency

9 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders II. Anemias of disordered iron metabolism and heme synthesis O Table 9-1, Figure 9-1 O Cytoplasmic maturation defect, microcytic/hypochromic anemia O Deficient iron -> iron deficiency anemia (IDA) O Defective utilization of iron -> sideroblastic anemia: defect in heme synthesis -> anemia of chronic disease: 1. Iron deficiency anemia O Decreased availability of dietary iron and chronic blood loss O Nutritional anemia (vitamin B12, folic acid) (1) Etiology - Iron absorption deficiency : defect in stomach, duodenum Gastrectomy, atrophic gastritis, vitamin C -> enhance absorption - Iron use increase (pregnancy) - Iron excretion increase (menstruation, hemorrhage) - Abnormal transferrin function

10 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders

11 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders (2) Pathophysiology O Iron deficiency -> defect in Hb synthesis -> anemia (3) Symptom symptom of anemia, koilonychia (spoon-shaped nail) glossitis, angular cheilitis, esophageal stricture (dysphagia), (4) Laboratory finding O Blood smear: Hypochromic microcyte, Reticulocyte: severe -> decrease Poikilocytosis: target cell O LaB - Hb, Hct -> decrease, RDW -> increase - MCV(Hct/RBC), MCH (Hb/RBC), MCHC (Hb/Hct) -> decrease - Serum iron -> decrease - TIBC -> increase (iron deficiency -> induce increased expression of transferrin) - UIBC: increase - Transferrin saturation -> decrease, Serum ferritin -> decrease O bone marrow - Iron staining: complete absence of intracellular iron deposit - Mild to moderate erythroid hyperplasia with a decreased M:E ratio O Iron-deficiency plus vitamin B 12 /folic acid deficiency -> normocytic

12 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders

13 COLLEGE OF HEALTH SCIENCES, DEPARTMENT OF BIOMEDICAL LABORATORY SCIENCE  Erythrocytic disorders