Erythrocyte Part 2 - Lecture Notes PDF

ERYTHROCYTE part 2 Dr. Nisreen Daffa Alla M.B.B.S, PhD (Human Physiology), MSc health Profession Education 1  OBJECTIVES The student should be able to:  Define anemia.  Differentiate between di...

ERYTHROCYTE part 2 Dr. Nisreen Daffa Alla M.B.B.S, PhD (Human Physiology), MSc health Profession Education 1  OBJECTIVES The student should be able to:  Define anemia.  Differentiate between different types of anemia  Identify the normal values for MCV, MCH, MCHC and their clinical uses.  Define polycythemia.  Differentiate between primary and secondary polycythemia.  Recognize the effect of anemia and polycythemia on the body. 2  ANEMIA Anemia is defined as: - Decreased hemoglobin. - Decreased RBC count. - Decreased Hematocrit [PCV]. below the normal range for age and sex. Therefore, decreased O2 carrying capacity of blood. 3 4  ANEMIA  How to differentiate between different causes of anemia? Hemoglobin, RBC, PCV [Hematocrit] MCV [Mean Cell Volume] MCH [Mean Concentration of Hemoglobin] MCHC [Mean Cell Hemoglobin Concentration] 5  RBCs indices MCV (Mean Cell Volume): the volume of average RBC MCV = PCV X 10 - Normal MCV = 90 fL or 90 μ3 RBC MCV > 95 fL are called macrocyte MCV < 80 fL are called microcyte MCH (Mean Concentration of Hemoglobin): mean concentration of Hemoglobin in each RBC. MCH = Hb X 10 - Normal MCH = 30 picogram [pg] RBC MCHC = Hb X 100 MCHC (Mean Cell Hemoglobin Concentration) hemoglobin present per 100 ml of RBC - Normal MCHC = 30 gram/100ml of RBC PCV 6  ANEMIA Classification of Anemia: 1. Nutritional Anemia: Caused by dietary deficiency of factors needed for Erythropoiesis. Deficiency of Iron: Iron deficiency anemia is called microcytic hypochromic anemia as RBC is small with less Hemoglobin. MCV MCH Iron deficiency anemia is common in pregnant women, exclusive breast fed babies, elderly with GIT cancers 7  ANEMIA 2. Pernicious Anemia A type of vitamin B12 deficiency caused by autoantibodies against intrinsic factor and/or gastric parietal cells (AMBOSS) Vitamin B12: need intrinsic factor for absorption from intestinal tract [terminal ileum]. Intrinsic factor is produced by Parietal cells of stomach. Pernicious Anemia is caused by autoimmune destruction of parietal cells thus leads to deficiency of Intrinsic factor and inability to absorb enough ingested vitamin B12. List some pathological conditions may cause deficiency of vitamin B12? Please refer to Vitamin B12 deficiency - AMBOSS Pernicious Anemia is megloblastic anemia (macrocytic normochromic anemia) MCV MCH 8  ANEMIA 3. Aplastic Anemia Caused by failure of bone marrow to produce RBC even though all necessary nutrients for Erythropoiesis are available. Causes of Aplastic Anemia - Excessive exposure to X-ray. - Exposure to radiation, e.g. bomb blast. - Chemotherapy for cancer. - Drugs. - Infections What are white blood cells and platelets counts in patients with aplastic anemia? Refer to AMBOSS Anemia – AMBOSS- aplastic anemia 9  ANEMIA 4. Hemolytic Anemia: Caused by excessive breakdown of RBC. Causes of Hemolytic Anemia - Malaria - Mismatched blood transfusion - Drugs - Congenital hemolytic anemias 1  ANEMIA Congenital hemolytic anemias: Sickle Cell Anemia: Hereditary disorder leads to excessive breakdown of RBCs Hemoglobin β chain is defective where valine replaces glutamate at position 6 in this amino acid chain. RBC is sickle shaped. 11 12  ANEMIA 5. Renal Anemia Anemia caused by kidney disease due to: - Decreased Erythropoietin secretion. 6. Hemorrhagic Anemia Caused by blood loss. - Acute Loss of blood e.g. car accident. - Chronic : heavy menstrual cycle 1  ANEMIA Effect of Anemia Anemia causes tissue hypoxia [decrease O delivery 2 to tissues] To compensate, body increases cardiac output. How In Anemia, blood viscosity is decreased to 1.5 times of water [normal viscosity 2.5 – 3 times of water]. Therefore, there is decreased peripheral resistance, it causes increased blood flow and increased venous return to heart, therefore, increased cardiac output & increase heart rate. 1 Symptoms and signs of anemia Fatigability Poor exercise tolerance Palpitations Pale skin and mucous membranes Jaundice 15  Treatments of anemia According to cause Iron, Vitamin B12, folic acid supplement Blood transfusion Bone marrow transplantation 16  POLYCYTHEMIA Polycythemia is characterized by increased number of RBC and increased Hematocrit. Types of Polycythemia 1. Primary Polycythemia 2. Secondary Polycythemia 1  POLYCYTHEMIA Primary Polycythemia is tumor like condition of bone marrow, where, there is increased production of RBC. RBC count may reach 11 million/mm3. Hematocrit may be 70-80%. 1  POLYCYTHEMIA Secondary Polycythemia is due to decreased O2 delivery to the tissues. It occurs in people living at high altitude as O2 available in the air is less. It occurs in people with chronic lung disease or cardiac failure. RBC count may be 6 to 8 million/mm3. 1  POLYCYTHEMIA Relative Polycythemia occurs when there is body fluid loss but no loss of erythrocytes. e.g. diarrhea, heavy sweating. This is not true Polycythemia as RBC are not increased, but only plasma volume is decreased. As RBC are concentrated in small plasma volume, this condition is called Relative Polycythemia. 2 21  POLYCYTHEMIA Effect of Polycythemia In Polycythemia, there is increased viscosity, therefore, blood flow is sluggish [slow]. Increased viscosity leads to increased peripheral resistance; therefore, increased blood pressure can occur [in 1/3rd of polycythemic people]. 2  Class room question How you differentiate between general causes of anemia: increased destruction and decreased production 23  Case study A 58 years old male admitted from a nursing home with a chief complaint of fatigue, headache and breathlessness on minimal exertion. For the past years he complained of nausea, vomiting and dyspepsia, His symptoms were ignored by the working staff. On further questioning he mentioned that his stool is often dark... He is a heavy smoker. On examination he looks cachexic, pale and tachycardic. Comment on the laboratory investigations? What do you think this patient is suffering from? 2 Lab investigations 25  REFERENCES  Anemia – AMBOSS  Human Physiology, Lauralee Sherwood, seventh edition.  Text book Physiology by Guyton &Hall,11th edition.  Text book of Physiology by Linda S. Contanzo, third edition.  Physiology by Berne and Levy, sixth edition. 26  Laboratory medicine – AMBOSS RBC parameters 27