1. Disorders of Red Blood Cells
Professor Myat Thandar
Department of Physiology
University of Medicine 1

2. Functions of RBCs O2 transport (Hb in the RBCs) CO2 transport
Acid-base balance

3. Functional Importance of the Biconcave Shape of RBCs
Larger surface area for O2 diffusion
Thinness of cell membrane enables O2 to diffuse easily
Flexibility of membrane facilitates the transport function

4. Network of Fibrous Proteins of RBCs
Spectrin and Ankyrin
Imparts elasticity and stability to membrane and allows RBCs to deform easily

5. Haemoglobin A natural pigment, reddish when oxygenated
4 polypeptide chains (a globin portion and a heme unit)

6. Haemoglobin F in Fetus Higher affinity for O2 than adult Hb
HbF is replaced within 6 months of birth with HbA

7. Haemoglobin Synthesis
Availability of iron for heme synthesis
Amount of iron: 2 g in women and 6 g in men
Clinically, decreased ferritin levels
usually indicate the need for prescription
of iron supplements.

9. Red Cell Production
Until 5, almost all bones; After 20, membranous bones
Approximately 1% of total RBC is generated from bone marrow each day
Reticulocyte count serves as an index of erythropoietic activity of bone marrow

10. Stages of Erythropoiesis
Hematopoietic stem cell (HSCs)
Unipotent committed stem cell
Proerythroblast (15-20 mm)
Early normoblast (12-16 mm)
Intermediate normoblast (10-14 mm)
Haemoglobinization begins
Late normoblast (10-14 mm)
Haemoglobinization ++
Nuclear disintegration
Reticulocyte (7-8 mm)
Nucleus remains only as strands of reticular element
Erythrocyte (7.5 mm)
IL-1, IL-6, IL-3 (interleukins)
GM-CSF, G-CSF, SCF
Erythropoietin
GM-CSF

11. Red Cell Production

12. Red Cell Maturation Reduction in the cell size
Increase in the amount of haemoglobin
Disappearance of nucleus, and
Change in staining characteristics of cytoplasm: basophilic to eosinophilic. This is partly due to a fall in content of RNA.

13. Erythropoietin

14. Human Erythropoietin Produced by recombinant DNA technology
Used for anaemia induced by chemotherapy in cancer patients, and HIV infected persons treated with zidovudine
In severe anaemia, retic count may be as much as 30% (normal about 1%); numerous erythroblasts may appear in the blood

15. Destruction of Red Blood Cells

16. Excretion of Bilirubins
Excess bilirubin elimination leads to
bilirubin gallstones
If red cell destruction and bilirubin
production is excessive, yellow discoloration of the skin, jaundice, occurs due to accumulation
of unconjugated bilirubin

17. Haemoglobinuria
Haemoglobin binding protein – Haptoglobin – in the plasma
Other plasma proteins – albumin – also binds to Hb
Extensive destruction of RBCs (haemolytic transfusion reactions), binding capacity is exceeded
Haemoglobinaemia and haemoglobinuria results

18. Red Cell Metabolism
2,3-DPG decreases affinity of Hb for O2, facilitating the release of O2 at tissue levels
Increased 2,3-DPG occurs in chronic hypoxia such as chronic lung diseases, anemia and residence at high altitude

19. Inhibition of Oxygen Haemoglobin Binding
Certain chemicals : nitrates and sulfates
Hb reacts with nitrite to form methaemoglobin
G6PD deficiency predisposes to oxidative denaturation of hemoglobin
with resultant red cell injury and lysis (oxidative stress generated by infection or exposure to certain drugs)

20. Laboratory Tests
Using automated blood cell counters: red cell content and indices
Red cell indices are used to differentiate type of anemias by size or color of red cells
Haemoglobin
Hematocrit
Mean corpuscular volume (MCV falls in microcytic and rises in macrocytic anemia)
Mean corpuscular haemoglobin concentration (normochromic or normal MCHC; hypochromic or decreased color or decreased MCHC)

21. Laboratory Tests Mean cell haemoglobin
A stained blood smear: information about size, color and shape of red cells and the presence of immature or abnormal cells
If blood smear is abnormal, bone marrow examination may be indicated
Bone marrow aspiration from posterior iliac crest or the sternum

22. Red cell count and Haemoglobin severity of anemia
Red cell characteristics
Size normocytic, microcytic or macrocytic
Color normochromic, hypochromic
Shape the cause of anemia

23. Anemia
Values of hemoglobin, hematocrit or RBC counts which are more than 2 standard deviations below the mean
HGB<13.5 g/dL (men) <12 (women)
HCT<41% (men) <36 (women)
Normal Hb Concentration
Western value Myanmar value
Male : 16 g / dL ( g/dL) g / dL
Female : 14 g / dL ( g/dL) g / dL

24. Pathophysiology of Anemia
Blood Loss
Decreased Production (lack of nutritional elements or bone marrow failure)
Increased Destruction (haemolysis)

25. Effects of Anemia
Manifestations of impaired oxygen transport and the resultant compensatory mechanisms
Reduction in red cell indices and hemoglobin levels
Signs and symptoms associated with the pathophysiologic process that causes anemia
Manifestations depend on its severity, the rapidity of
its development and the person’s age and health status

26. Symptoms of Anemia

27. Impaired oxygen transport and tissue hypoxia
Weakness, fatigue, dyspnoea and angina
Brain hypoxia results in headache, faintness and dim vision
Redistribution of blood results in pallor of skin, conjunctiva, mucous membranes and nail beds

28. Compensatory Mechanisms
Tachycardia, palpitations and increased cardiac output
A flow type of systolic murmur
Ventricular hypertrophy and high output heart failure
Accelerated erythropoiesis results in diffuse bone pain and sternal tenderness
Haemolytic anemia : jaundice
Aplastic anemia : petechiae and purpura due to reduced platelet functions

29. Blood Loss Anemias
Depends on rate of haemorrhage and blood loss is external or internal
Rapid loss causes circulatory shock and collapse; fall in red cell count, Hb, hematocrit due to fluid shift into vessels
Initially red cells are normocytic, normochromic
Increased erythropoietin and retic count
Slow loss (GI bleeding, menstrual disorders) causes anemia; signs and symptoms develop if the amount of red cell mass loss reach 50% (Hb <8 g/dL)(iron deficiency anemia)
External bleeding leads to iron loss and iron deficiency

30. Haemolytic Anemias
Characterized by premature destruction of red cells, retention in the body of iron and other products of Hb destruction and increased erythropoiesis
Normocytic normochromic red cells
Increased retic count in the circulating blood
Haemoglobinemia, haemoglobinuria, jaundice, haemosiderinuria

31. Haemolytic Anemias
Intravascular haemolysis is less common, caused by complement fixation in transfusion reactions, mechanical injury or toxic factors
Extravascular haemolysis occurs when RBCs are less deformable to traverse splenic sinusoids, characterized by anemia and jaundice
Intrinsic : defects of red cell membrane, haemoglobinopathies (sickle cell disease and thalassemias) and enzymes defect
Extrinsic or acquired : drugs, bacteria and other toxins, antibodies and physical trauma

32. Inherited Disorders of Red Cell Membrane
Hereditary spherocytosis : abnormalities of spectrin and ankyrin
Mild hemolytic anemia, jaundice, splenomegaly and bilirubin gallstones
Splenectomy done to reduce red cell destruction and blood transfusion in a crisis

33. Sickle Cell Disease
Haemoglobin S (point mutation in the β chain of Hb, valine for glutamic acid)
Haemolytic anaemia, jaundice, gallbladder stones, pain and organ failure (infarction of organs)
Hb S becomes sickled when deoxygenated or at a low oxygen
Deoxygenated Hb aggregates and polymerizes in the cytoplasm, creating a semisolid gel that changes the shape and deformability of the cell

34. Red Cell Sickling Chronic hemolytic anemia Blood vessel occlusion
Associated conditions: cold, stress, physical exertion, infection, illnesses that cause hypoxia, dehydration or acidosis

35. Features of Sickle Cell Disease

36. Diagnosis and Treatment
Neonates : clinical findings and haemoglobin electrophoresis
Prenatal diagnosis : analysis of fetal DNA by amniocentesis
Prevention of sickling episodes, symptomatic treatment and treatment of complications (prophylactic penicillin and full immunization)
Cytotoxic drug – hydroxyurea – to allow synthesis of more HbF and less HbS
Nitric oxide appears to be a promising new drug
Bone marrow or stem cell transplantation

37. Thalassemias
Inherited disorders of haemoglobin synthesis and decreased synthesis of α or β globin chains of HbA
Heterozygous or homozygous

38. Thalassemias
β thalassemias – Cooley anaemia or Mediterranean anemia – common in Mediterranean population of southern Italy and Greece
α thalassemias more common among Asians
Anemia due to low production of affected chain and continued production and accumulation of unaffected globin chain
Reduced Hb synthesis leads to hypochromic microcytic anemia; accumulation of unaffected chain interferes with normal red cell maturation, and membrane changes leading to hemolysis and anemia

39. β - thalassemias
Excess α chains are denatured to form precipitates (Heinz bodies) in the bone marrow red cell precursors
Heinz bodies impair DNA synthesis and damage to red cell membrane
Coagulation abnormalities, thrombotic events (stroke and pulmonary embolism) in moderate to severe form

40. Pathophysiology of β - thalassemias
Thinning of cortical bones

41. Treatment of β - thalassemias
Regular transfusion to maintain Hb at 9 to 10 g/dL
Iron chelation therapy to reduce iron load
Stem cell transplantation
Stem cell gene replacement

42. α - thalassemias Synthesis of globin chains is controlled by 4 genes
Deletion of single gene : silent carrier; two genes is α thalassemia trait
Deletion of three genes leads to unstable aggregates of α chains – HbH
Four globin chains are deleted : Hb Bart (extremely high oxygen affinity, cannot release oxygen in the tissues
Chronic hemolytic anemia

43. Inherited Enzymes Defect
G6PD deficiency
RBCs vulnerable to oxidants, direct oxidation of Hb to methaemoglobin, and denaturation of Hb to form Heinz bodies
Anti-malaria drug primaquine, the sulfonamides, nitrofurantoin, aspirin, phenacetin, some chemotherapeutics and other drugs cause hemolysis
Diagnosed through G6PD assay or screening test

44. Acquired Hemolytic Anaemias
By direct membrane destruction or antibody mediated lysis
Various chemicals, toxins, venoms, malaria infection, prosthetic heart valves, vasculitis, severe burns, septicaemia, thrombotic thrombocytopenic purpura, renal disease
Warm reacting antibodies (IgG) and cold reacting antibodies (IgM)
Warm antibodies bind with Ag on red cell membrane (Rh Ag), resulting in spherocytosis and destruction by RE system
Cold antibodies activate complements; as in lymphoproliferative disorder and idiopathic

45. Rh incompatibility

47. Coomb’s Test
Direct Antiglobulin Test (DAT) is positive in autoimmune hemolytic anaemia, erythroblastosis fetalis, transfusion reactions, transfusion reactions and drug induced hemolysis
Indirect antiglobulin test is used for antibody detection and crossmatching before transfusion

48. Anemias of Deficient Red Cell Production
Deficiency of nutrients for hemoglobin synthesis (iron)
Deficiency of nutrients for DNA synthesis (Cobalamin or folic acid)
Marrow is replaced by nonfunctional tissues

49. Iron Deficiency Anemia
Dietary deficiency (vegetarians)
Loss of iron through bleeding (peptic ulcer, polyps, cancer, menstrual bleeding)
Increased demands (growing children, pregnancy)

50. Iron Metabolism

51. Characteristics of Iron Deficiency Anemia
Low haemoglobin and hematocrit
Decreased iron stores, low serum iron and ferritin
Red cells number decreased and are microcytic and hypochromic
Poikilocytosis (irregular shape)
Anisocytosis (irregular size)
Reduced MCHC and MCV
Membrane changes predispose to
hemolysis

52. Manifestations of Iron Deficiency Anemia

53. Treatment of Iron Deficiency Anemia
Prevention and treatment of the cause
Ferrous sulfate
Parenteral iron (iron dextran or sodium ferric gluconate)
Initial test dose to prevent severe anaphylactic reactions

54. Megaloblastic Anemia Impaired DNA synthesis
Enlarged red cells (MCV >100 fL)
Develop slowly
Vitamin B12 and folic acid
deficiency

55. Vitamin B12 Deficiency Anemia: B12 Absorption

56. Pernicious Anemia Atrophic gastritis
Autoimmune destruction of gastric mucosa
Gastrectomy, ileal resection, inflammation or neoplasms in terminal ileum, malabsorption syndrome
MCV elevated; MCHC is normal

57. Vitamin B12 Containing Food
Normal body stores of 1000 to 5000 µg provide the daily requirement of
1 µg for a number of years.
Therefore, deficiency develops slowly

59. Diagnosis of B12 Deficiency
The Shilling test – 24 hour urinary excretion of radiolabelled vitamin B12 administered orally
Detection of parietal cell and intrinsic factor antibodies
Lifelong intramuscular or high oral doses of vitamin B12 is required

60. Folic Acid

61. Folic Acid Deficiency
Total body stores amount to 2000 to 5000 µg and 50µg is required
in the daily diet. A dietary deficiency may result in anaemia in a few months
Pregnancy increases the need for folic acid 5 to 10 fold

62. Aplastic Anemia Reduction of all 3 hemopoietic cell lines
Onset may be insidious but may be abrupt and severe

64. Therapy in Aplastic Anemia

65. Therapy in Aplastic Anemia
Immunosuppressive therapy with lymphocyte immune globulin
Avoid offending agents
Antibiotics for infection
Red cell transfusion to correct anaemia
Platelets and corticosteroid therapy to minimize bleeding

66. Chronic Disease Anemia
Occur as a complication of chronic infections, inflammation, cancer and chronic kidney diseases
Short red cell life span; deficient red cell production; a blunted response to erythropoietin, and low serum iron
Mild anemia – normocytic and normochromic – with low reticulocyte counts
In chronic renal diseases, uremic toxins and retained nitrogen interfere with actions of erythropoietin; hemolysis and blood loss associated with hemodialysis and bleeding tendencies also contribute to anemia

67. Therapy in Chronic Disease Anemia
Short-term erythropoietin therapy
Iron supplementation
Blood transfusions
In future – iron chelating agents and cytokines to stimulate erythropoietin production

68. Thank You