Red blood cells erythrocytes

1. 1
PHYSIOLOGY OF RBC
Dr.LAKSHMI.S.MENON
PG STUDENT

2. INDEX
INTRODUCTION
HISTORY
COMPARATIVE PHYSIOLOGY
RED CELL MORPHOLOGY
ERYTHROPOIESIS
DESTRUCTION OF RBC AND FATE
APPLIED PHYSIOLOGY
a) DISORDERS OF RBC
b) DIAGNOSTICS
c) THERAPEUTICS
d) RECENT ADVANCES
REFERENCES
SUMMARY
2

3. BLOOD
• Circulatory system distributes
• O2 ,Nutrients, Hormones Tissues
• CO2 Lungs
• Metabolites Kidneys
• Blood : liquid connective tissue pumped through a
closed system of blood vessels by the heart.
3

4. COMPOSITION OF BLOOD
• Consists of protein-rich fluid known as plasma, in which
are suspended cellular elements
4

5. FUNCTIONS OF RBCs
1. The most important function of red cell is to
transport oxygen from lungs to the tissue.
2. RBC also participate in carbon dioxide transport
from tissues to lungs and maintenance of acid base
balance.
3. Red cells contribute to 50% of viscosity of blood.
4. Antigen on red cell membrane helps in blood
group classification.
5

6. HISTORY
•1695 Antoni van leeuwenhoek first described the
shape of “red corpuscles”.
•1740 Vincenzo Menghini in Bologna was able to
demonstrate the presence of iron by passing magnets
over the powder or ash remaining from heated red
blood cells.
6

7. HISTORY
•1794. Pierre-Adolphe Piorry The first attempt to
count red blood cells
•1818 Karl Vierdordt first exact red blood cell
counting method
•1852 Karl Vierordt and his student H. Welcher.
discovered Iron deficiency anemia
7

8. HISTORY
•1901 Karl Landsteiner published his discovery
of the three main bloodgroups—A, B, and C
(which he later renamed to O). Landsteiner
described the regular patterns in which
reactions occurred when serum was mixed with
red blood cells, thus identifying compatible and
conflicting combinations between these blood
groups
8

9. HISTORY
•1902 Alfred von Decastello and Adriano Sturli,
two colleagues of Landsteiner, identified a fourth
blood group—AB.
•1903
•JA Capps measured red cell size by noting the
diameter of red cells in blood smear under a
microscope.
•Osler First description of syndrome of
polycythemia vera
9

10. HISTORY
•1914 George Hayem who is remembered for
diluting fluid used for counting red blood cells,He
studied microscopically the size shape and
colouration of blood cells and described their
appearance in various types of anemia.
•1915 Rous & Turner developed the first RBC
storage solution (a mixture of citrate and glucose)
for storing rabbit RBC for use in a heterophile
agglutination test for syphilis
10

11. HISTORY
•1922 O. Neubauer counting grid became the most
used
•1925
•Gorter and Grendel provided the first insights into
the structure of the rbc membrane
•Cooley and Lee First description of thalassemia
11

12. HISTORY
•1934 George Hoyt Whipple along with George R
Minot and William P Murphy awarded Nobel
prize for their work on liver treatment of pernicious
anemia
12

13. HISTORY
•1934 Maxwell Myer Wintrobe Classification of
anemias based on RBC indices
•1939 Karl Landsteiner, Alexander Wiener, Philip
Levine and R.E. Stetson. Discovered the Rh blood
group system
13

14. HISTORY
14
•1942 Maxwell Myer Wintrobe wrote his book
clinical hematology which was first dedicated work
in the field till date it remains most authoritative
book.

15. HISTORY
•1947 William Bosworth Castle Established the role
of intrinsic factor in pernicious anemia .
•1950 Kurt Reissmann showed exsistence of
erythropoietin by experiments on parabiotic rats.
•1959 Dr.Max Perutz by use of xray
crystallography was able to unravel the structure of
hemoglobin.
15

16. HISTORY
•2005 Douay , Giarratana Stem cells are being used
as a source of RBC cultivation in vitro
•2011 O’Neill and Reddy the role of RBCs in
systemic circadian rhythm maintenance
•May 2012 The oldest intact red blood cells ever
discovered were found in otzi the Iceman, a natural
mummy of a man who died around 3255 BCE.
16

17. HISTORY
•2017 Kaestner and Minetti Lacking translation, the
maintenance of RBC function under the stressful
conditions in the circulation is impressive and not
fully understood
• 2022 Annamaria Russo , Ester Tellone
Implication of COVID-19 on Erythrocytes
Functionality COVID-19 causes significant changes
in the size and rigidity of RBCs; a decrease in the
hematocrit level and increased RBCs amplitude
referred to as RDW (red blood cell distribution
width)
17

18. COMPARATIVE PHYSIOLOGY
18

19. COMPARITIVE PHYSIOLOGY
INVERTEBRATES-
 hemoglobin circulates as free protein in the
circulatory fluids and is not enclosed in RBCs.
When it is free in human plasma, about 3% of it
leaks through the capillary membrane into the tissue
spaces or through the glomerular membrane of the
kidney into the glomerular filtrate each time the
blood passes through the capillaries.
Therefore, hemoglobin must remain inside RBCs to
perform its functions in humans effectively
19

20. COMPARATIVE PHYSIOLOGY
•VERTEBRATES
The vast majority of vertebrates
including mammals and humans, have RBC’s
20

21. VERTEBRATES
• The only known vertebrates without red blood cells
are the crocodile icefish (family Channichthyidae);
they live in very oxygen-rich cold water and transport
oxygen freely dissolved in their blood. While they no
longer use hemoglobin, remnants of hemoglobin
genes can be found in their genome.
21

22. FROG RBC
22

23. DIFFERENCES BETWEEN HUMAN AND
FROG BLOOD CELLS
FROG BLOOD CELLS:
• Frog red blood cells are
larger than the human red
blood cells.
• Frog red blood cells are
elliptical in shape.
• Frog blood cells contain
nuclei and other
organelles.
• Frog blood cells are capable
of dividing by themselves
since they contain nuclei.
HUMAN BLOOD CELLS:
• Human red blood cells are
small.
• Human red blood cells are
spherical in shape.
• lack nuclei and other
organelles.
• Human blood cells are
unable to divide.
23

24. 24

25. RED CELL MORPHOLOGY
25

26. RED CELL MORPHOLOGY
•Shape : Biconcave
•Size : 7.8 (7 to 8) µm in diameter
•Surface area : 140 µm2
•Volume : 78 to 94µm3
•Thickness : 2 µm at the periphery
≤1 µm at the centre
26

27. ADVANTAGES OF BICONCAVITY
OF RBCs
Do not easily lyse when blood becomes hypotonic.
It increases the surface area for exchange of gases
(oxygen and carbon dioxide).
Facilitates RBCs movement through the narrow
capillaries
27

28. RED CELL COUNT
•In adult
• males: 4.5–6 (average 5.2) millions per cu mm of
blood
•females : 4–5.5 (average 4.7) millions per cu mm
of blood
•In newborns : 6–8 millions per cu mm of blood
•In children : 3–5 millions per cu mm of blood
28

29. RED CELL MORPHOLOGY
•RED CELL MEMBRANE
•It is made up of three major structural elements
1. Lipid bilayer
2. Integral proteins
3. Membrane skeleton
29

30. RED CELL MEMBRANE
30

31. RED CELL MEMBRANE
•LIPID BILAYER
•Composed of phospholipid and cholesterol.
•Provides an impermeable barrier between cytoplasm
and external environment.
•Maintain a slippery exterior so that red cell do not
stick to vascular endothelium
31

32. RED CELL MEMBRANE
•INTEGRAL PROTEINS
•Embedded in lipid bilayer
•Important membrane proteins are
•band – 3 proteins
•Glycophorins
•RhD protein
•various ion channels
32

33. RED CELL MEMBRANE
•MEMBRANE SKELETON
•Present on the the internal side of red cell membrane
•Membrane skeletal proteins are :
•Spectrin
•Ankyrin
33

34. RED CELL MORPHOLOGY
•Composition :
I. 62.5% Water
II. 35% Haemoglobin
III. 2.5%:
(a) Sugar – glucose
(b) Lipids - cephalin, cholesterol and lecithin
(c) Protein - Glutathiones
(d) Enzymes of glycolytic system, carbonic
anhydrase and catalase.
(e) Vitamin derivatives
(f) Ions – Na+, K+, Ca2+, PO4
3- , SO4
2-
34

35. HEMOGLOBIN
•The red, oxygen carrying pigment in the RBCs is
haemoglobin.
•It consists of the protein globin (polypeptide)
united with the pigment haem (heme).
•The synthesis of hemoglobin begins in
polychromatophil erythroblasts and continues
even into the reticulocyte stage of the RBCs
35

36. HEMOGLOBIN STRUCTURE
•Heme
•Heme is a complex molecule made up of a series of
tetrapyrrole rings, terminating in protoporphyrin,
with a central iron atom.
•Globin
•This is a protein substance that consists of two pairs
of polypeptide chains.
•Each amino acid chain is attached to a heme moiety
to form a single hemoglobin molecule
36

37. 37

38. BASIC CHEMICAL STEPS IN THE
FORMATION OF HEMOGLOBIN.
38

39. VARIETIES OF HAEMOGLOBIN
1. NORMAL Hb
• Adult Hb
• Fetal Hb
• Embryonic Hb
2. ABNORMAL Hb
• Hb S
• Hb C
• Hb E
• Hb M
• Unstable Hb
39

40. NORMAL HEMOGLOBIN
1. ADULT HEMOGLOBIN
Types: Hb A and Hb A2.
Hemoglobin A (Hb A)
•major Hb (97% ).
•It consists of two α and two β chains
•Hb A is detected in small amount in the fetus as
early as the eighth week of intrauterine life.
•During the first few months of post-natal life, Hb
A replaces Hb F and the adult pattern is fully
established in 6 months.
40

41. NORMAL HEMOGLOBIN
1. ADULT HEMOGLOBIN
•Hemoglobin A2 (Hb A2)
• This is the minor hemoglobin in the adult red cells.
•It has the structural formula of α2δ2.
•Hb A2 is present in very small amounts at birth and
reaches the adult level of 3% during the first year of
life. Its concentration increases in some anemias.
41

42. NORMAL HEMOGLOBIN
2. FETAL HEMOGLOBIN
•Hb F is the major hemoglobin in intrauterine life
•. It has the structural formula of α2γ2.
•Hb F accounts for 70 to 90% of hemoglobin at term.
• It then falls rapidly to 25% in one month, and 5%
in six months.
•The adult level of 1% is not reached in some
children until puberty. Hb F concentration in adults
increases in some types of anemia,
hemoglobinopathies, and sometimes in leukemia.
42

43. NORMAL HEMOGLOBIN
•FETAL HEMOGLOBIN
•Hemoglobin Bart’s (Hb Bart’s)
• This is the minor hemoglobin present in fetal life.
• It consists of 4 gamma (γ) chains, γ4.
•Hb Bart’s concentration increases in fetal life in
thalassemia
43

44. NORMAL HEMOGLOBIN
3. EMBRYONIC HEMOGLOBIN
•These hemoglobins are confined to the very early
stages (embryonic stage) of development.
•There are 3 embryonic hemoglobins:
•1. Gower Hb 1: It consists of 2 zeta and 2 epsilon
chains (ζ2ε2).
•2. Hb Gower 2: It consists of 2 alpha and 2 epsilon
chains (α2ε 2)
•3. Hb Portland: It consists of 2 zeta and 2 gamma
chains (ζ 2γ2).
44

45. ABNORMAL HEMOGLOBINS
•HbS
•Valine replaces glutamic acid at 6th position
•Causes sickling of red cells on exposure to
hypoxia
•HbC
•Lysine replaces glutamic acid at 6th position
•Shortens rbc survival
45

46. ABNORMAL HEMOGLOBINS
•HbE
•Glutamic acid replaces lysine acid at 26th position
•Produces microcytosis
•HbM
•Tyrosine replaces histidine acid at 63rd position
•Methemoglobin formation
•Unstable Hb
•Hb variants undergo denaturation and precipitate
in red cells as Heinz bodies
46

47. FUNCTIONS OF HEMOGLOBIN
1. It transports oxygen from lungs to the tissues by
forming oxyhemoglobin and carbon dioxide from
tissues to lungs by forming
carbaminohemoglobin.
•Each gram of hemoglobin can combine with 1.34
ml of oxygen if the hemoglobin is 100% saturated
2. Hemoglobin acts as a buffer in maintaining
blood pH.
47

48. FUNCTIONS OF HEMOGLOBIN
3. Hb serves to destroy physiologically important
nitric oxide molecule.
4. It imparts red color to the blood. Erythrocytes look
red due to the presence of hemoglobin in them,
which is a red pigment.
48

49. NORMAL VALUES OF HEMOGLOBIN
IN RBCs
• Average Hemoglobin in the whole blood
49
• 13-18 g /dl
Men
• 11.5 – 16 g/dl.
Women
• 6 months – 6 years
• 13.6-19.6 g/dl
• 6-14 years
• 12 g/dl
Children
• 11 g/dl
Pregnant women

50. METABOLISM OF IRON
• The total quantity of iron in the body averages 4 to 5
grams
• About 65% of which is in the form of hemoglobin.
• 15% to 30% is stored for later use, mainly in the
reticuloendothelial system and liver parenchymal cells,
principally in the form of ferritin.
• About 4% is in the form of myoglobin
• 1% is in the form of the various heme compounds that
promote intracellular oxidation
• 0.1% is combined with the protein transferrin in the
blood plasma,
50

51. TRANSPORT, STORAGE, AND
METABOLISM OF IRON
51

52. ERYTHROPOIESIS
•Definition: Erythropoiesis is defined as the process
of formation of red cells. This is an important
component of hematopoiesis.
•Hematopoiesis: The production of all types of blood
cells including formation, development, and
differentiation of blood cells
52

53. GENESIS OF BLOOD CELLS
53

54. GENESIS OF BLOOD CELLS
54

55. 55

56. SITES OF PRODUCTION OF
RED BLOOD CELLS
•Areas of the Body That Produce Red Blood Cells.
•There are three stages of erythropoiesis:
mesoblastic, hepatic and medullary.
Mesoblastic Stage
•In the early weeks of embryonic life,
•primitive nucleated RBCs are produced in
the yolk sac.
56

57. SITES OF PRODUCTION OF RED
BLOOD CELLS
Hepatic Stage
•5th week of gestation
•Liver (main organ) but reasonable numbers are
also produced in the spleen and lymph nodes.
Medullary Stage
• From the 5th month of intrauterine life, the bone
marrow starts forming red cells .
• After birth, bone marrow becomes the sole site
of erythropoiesis.
57

58. SITES OF PRODUCTION OF
RED BLOOD CELLS
2. Extramedullary erythropoiesis in postnatal life is
always considered abnormal.
3. Till adolescent period, marrow cavities of all
bones are involved in erythropoiesis, after which
erythropoiesis regresses in the limb bones.
4. After the age of 20–30 years, erythropoiesis is
mostly limited to sternum, ribs, vertebrae, skull,
pelvic and pectoral girdles
58

59. RBCs PRODUCED IN
BONEMARROW OF DIFFERENT
BONES AT DIFFERENT AGES
59

60. STAGES OF DIFFERENTIATION OF
RED BLOOD CELLS
60

61. GENESIS OF BLOOD CELLS
61

62. 62

63. REGULATION OF ERYTHROPOIESIS
63

64. HYPOXIA
• Hypoxia means lack of oxygen at tissue level. It is the
most potent stimulus for the production of RBCs.
Hypoxia causes stimulation of bone marrow thereby
increases RBC production. This effect is mediated by
erythropoietin.
• ERYTHROPOIETIN
• Erythropoietin or Haemopoietin or Erythrocyte
stimulating factor (ESF) or Erythropoiesis stimulating
hormone (ESH)
• It is a glycoprotein, 74% protein and 26% carbohydrate;
contains 165 amino-acids, molecular weight 46,000; half
life: 5 hours.
64

65. SOURCE AND METABOLISM
1. Mainly (85%) secreted by kidneys probably by
interstitial cells (or cells in the endothelium) of the
peritubular capillaries.
2. 15% produced by extra renal sources like liver
parenchymal cells and cells of tissue macrophage
system . The hypoxic stimulus has to be much greater
than in normal persons to trigger extra renal
erythropoietin production.
• Inactivated in the liver
•kidneys; main site of excretion-urine
65

66. FACTORS AFFECTING
ERYTHROPOIETIN PRODUCTION
1. Increase
(i) Hypoxia due to:
(a) haemorrhage
(b) high altitude (secondary to alkalosis)
(c) cardio-respiratory disturbances
(d) methaemoglobin excess
66

67. ERYTHROPOIETIN
67

68. FACTORS AFFECTING
ERYTHROPOIETIN PRODUCTION
(ii) Vasoconstrictor agents (catecholamines)
(iii) Nucleotides e.g. cAMP, NAD and NADP.
(iv) Products of RBC destruction
(v) Hormones
(a) Thyroxine
(b) Anterior pituitary hormones
(c) Androgens
(vi) Others e.g. cobalt salts.
68

69. FACTORS AFFECTING
ERYTHROPOIETIN PRODUCTION
2. Decrease
(i) Oestrogen
(ii) Chronic renal diseases
(iii) Protein deficiency
(iv) Cirrhosis of the liver
(v) Chronic inflammatory diseases
69

70. B. SPECIAL MATURATION FACTORS
DIETARY FACTORS
(i) Proteins help in 'globin' formation.
(ii) Iron, manganese, copper, cobalt, nickel help in
'haem’ formation.
(iii) Calcium increases iron absorption from GIT.
(iv) Vitamins C, B12 and folic acid help in synthesis
of nucleic acid.
70

71. B. SPECIAL MATURATION FACTORS
CASTLES INTRINSIC FACTOR
•It is a glycoprotein; produced by the parietal
(oxyntic) cells of the stomach
•I.F. helps in absorption of vitamin B12 from ileum.
EXTRINSIC FACTORS
•These are present in certain foods and are essentially
vitamin B12 and folic acid
•I.F. with extrinsic factor form haematinic principle
which helps in the maturation of RBCs
•Therefore deficiency of any one of them causes
maturation failure and will lead to Megaloblastic
Anaemia. 71

72. DESTRUCTION OF RBC AND FATE
72

73. APPLIED PHYSIOLOGY
RBC DISORDERS
DIAGNOSTICS
THERAPEUTICS
RECENT ADVANCES
73

74. RBC DISORDERS
•ANEMIA
•IRON DEFICIENCY ANEMIA
•THALASSEMIA
•MEGALOBLASTIC ANEMIA
•PERNICIOUS ANEMIA
•HEREDITARY SPHEROCYTOSIS
•SICKLE CELL DISEASE
•POLYCYTHEMIA
74

75. ANEMIA
Anemia rarely is a disease by itself; almost always it is a sign of an acquired or
genetic abnormality
75

76. DEFINITION
•Anemia means deficiency of hemoglobin in the
blood, which can be caused by too few RBCs or too
little hemoglobin in the cells.
•Anemia may be practically defined as a state in
which the blood hemoglobin level is below the
normal range for the patient’s age and sex
•(Males < 13 g/dL; females < 12 g/dL by WHO)
76

77. 77

78. PRICE JONES CURVE
78

79. IRON DEFICIENCY ANEMIA
•Causes of Iron Deficiency
1. Increased iron utilisation (increased demand)
•Postnatal growth spurt
•Adolescent growth spurt
•Erythropoietin therapy
2. Physiologic iron loss
•Menstruation
•Pregnancy
79

80. CAUSES OF IRON DEFICIENCY
3. Pathologic iron loss
•Acute or chronic inflammation.
•Gastrointestinal bleeding
•Genitourinary bleeding
•Pulmonary hemosiderosis
•Intravascular haemolysis
•Phlebotomy for polycythaemia rubra vera
80

81. CAUSES OF IRON DEFICIENCY
4. Decreased iron intake
•Cereal rich diet
•Pica, food fads, malabsorption
81

82. CLINICAL FEATURES
•Patients may have
•Angular stomatitis
•Atrophic glossitis,
•Koilonychia
•Brittle hair
•Pruritus
•Pica
•Plummer-Vinson syndrome
•Menorrhagia
82

83. INVESTIGATIONS
1. Hemoglobin level:
•When Hb is greater than 10 gm/dl : symptoms of
anemia develop only on exertion or on exposure to
hypoxia or high altitude.
• If Hb level is less than 7 gm/dl, patient is
symptomatic even at rest.
•There is also loss of pigmentation in palmar
crease.
83

84. INVESTIGATIONS
2. Microcytic, hypochromic RBCs in the peripheral
smear.
84

85. INVESTIGATIONS
3. Raised platelet count may suggest bleeding.
4. Perl’s Prussian blue technique demonstrates
empty iron stores in the bone marrow.
5. Serum ferritin level is low
•It is often less than 12 mcg/L;
•values > 80 mcg/L, rules out iron deficiency
anaemia
6. Iron absorption is increased and the total iron
binding capacity rises.
85

86. INVESTIGATIONS
86

87. MANAGEMENT
1. Treat the underlying cause.
2. Iron replacement by ferrous sulphate 200 mg tds
orally.
•Oral therapy is safest and cheapest.
•Continue until haemoglobin is normal and for 6-8
months to replenish stores.
87

88. MANAGEMENT
3. Parenteral iron therapy: It is given for those who
are
•unable to absorb iron from the GI tract or to those
•who have intolerance to oral iron.
•100 mg of iron (IM) are required to increase the
haemoglobin level by 4% but the total dose of iron
should not exceed 2.5 gm.
88

89. THALASSAEMIA
•In thalassemia's, there is a reduced rate of
production of one or more globin chains leading to
precipitation of globin, and anemia occurs as a result
of ineffective erythropoiesis and hemolysis.
• This is common in Mediterranean areas and Far
east.
89

90. TYPES
1. Alpha thalassemia (reduced production of alpha
chains)
2. Beta thalassemia (reduced production of beta
chains)
3. Haemoglobin H disease
4. Hb Barts
5. Beta thalassaemia intermedia
90

91. BETA THALASSAEMIA MAJOR
(HOMOZYGOTES)/COOLEY’S ANAEMIA
•Anaemia is very severe and the patients live only
for a short time without blood transfusion.
•absent b-chains and only with insoluble a-chains
are toxic to the erythroblasts resulting in their
intramedullary destruction which causes ineffective
bonemarrow expansion by the release of
erythropoietin in response to anaemia.
91

92. BETA-THALASSAEMIA MAJOR
•Bone marrow hyperplasia
produces frontal bossing and
prominent malar eminences
which is seen in the skull X-
ray as ‘hair on end’
appearance
•growth retardation,
•Splenomegaly
•hepatomegaly
•cardiomegaly.
•characteristic chip-munk
facies
92

93. BETA-THALASSAEMIA MINOR
(HETEROZYGOTES)
•The course is very mild
•often this anaemia is detected only when a therapy
for a mild hypochromic anaemia fails.
• Symptoms are minimal.
93

94. ALPHA-THALASSAEMIA
•Both sexes are affected.
•It may present as
•hydrops fetalis (all genes deleted) or
• haemoglobin H (3 genes deleted), or
•mild hypochromic microcytic anaemia (2 genes
deleted)
•asymptomatic (1 gene deleted).
94

95. INVESTIGATIONS
1. Thalassaemia major
a. Profound hypochromic anaemia, severe red cell
dysplasia and plenty of target cell
95

96. INVESTIGATIONS
b. Absence or severe reduction of HbA
c. Raised HbF
d. Family history showing both parents having
thalassaemia minor.
96

97. INVESTIGATIONS
2. Thalassaemia minor
a. Mild anaemia, microcytic hypochromic RBCs
b. Some target cells, punctate basophilia
c. Raised HbA2 4-6%
d. Family history with one parent having thalassaemia
minor.
97

98. MEGALOBLASTIC ANAEMIA
•This term refers to abnormal haematomyelopoiesis
•characterised by dys-synchronous nuclear and
cytoplasmic maturation in all myeloid and erythroid
cell lines due to aberrant DNA synthesis as a result
of single or combined deficiency of either cobalamin
(Vit B12) or folate.
98

99. CAUSES OF VITAMIN B12
DEFICIENCY
1. Inadequate intake: Vegans (rare) pure
vegetarians
who do not consume milk and milk products.
2. Malabsorption:
a. Defective release of cobalamin from food
b. Inadequate production of intrinsic factor (IF)
c. Disorders of terminal ileum
d. Competition for cobalamin
e. Drugs – PAS, Neomycin, Colchicine
99

100. CAUSES OF FOLATE DEFICIENCY
1. Dietary cause
2. Malabsorption
3. Increased demand of folate-pregnancy, cell
proliferation as in hemolysis, neoplasia,
hyperthyroidism,ineffective erythropoiesis
4.Drugs -phenytoin, methotrexate, trimethoprim,
pyrimethamine,alcohol
100

101. CLINICAL FEATURES
Pallor
 smooth tongue
cardiac “hemic”systolic murmur
hepatomegaly, rarely splenomegaly.
Neurologic picture in vitamin B12 deficiency ranges
from
mental inattentiveness to severe mental confusion
dorsal and lateral column signs (subacute combined
degeneration).
101

102. INVESTIGATIONS
1. Blood film shows hypersegmented polymorphs
102

103. 103

104. INVESTIGATIONS
2. Increased ESR
3. Serum B12 level
4. Red cell folate level
5. Bone marrow biopsy
a. Megaloblastic
104

105. INVESTIGATIONS
6. Schilling test:
• It helps to identify the cause of B12deficiency.
• This determines whether a low B12 is due
to malabsorption or lack of intrinsic factor by
comparing the proportion of an oral dose (1 mg) of
radioactive B12 excreted in urine with and without
the concurrent administration of intrinsic factor.
105

106. INVESTIGATIONS
•The blood must be saturated prior by giving an IM
dose of 1000 mg of B12.
•If intrinsic factor increases absorption, the lack of it
is likely to be the cause.
•If not, look for other causes like blind loop
diverticula and terminal ileal disease.
106

107. MANAGEMENT
•In B12 deficiency,
•hydroxocobalamin 1000 mcg twice during the first
week, then 1000 mcg weekly for a further 6 doses
•Rapid regeneration of the blood depletes the iron
reserves of the body and hence ferrous sulphate 200
mg daily should be given soon after the
commencement of treatment and the picture will be
dimorphic then.
. In folate deficiency
• 5 mg of folic acid/day orally is given.
• 5 mg once a week is given as maintenance Therapy.
107

108. HEREDITARY SPHEROCYTOSIS (HS)
•This is inherited as an autosomal dominant
disorder.
•There is a qualitative and quantitative deficiency of
vital skeletal proteins of RBC membrane namely
spectrin and/or ankyrin.
•There are defects in cytoskeletal proteins.
•Ankyrin – 50% of patients
•Protein 3 – 25% of patients
•Spectrin – 25% of patients
•Protein 4.2 – less often
108

109. HEREDITARY SPHEROCYTOSIS (HS)
Loss of normal skeletal proteins of RBC membrane
results in loss of lipids from the membrane leading to
loss of surface area and altered RBC morphology.
Hence, RBCs lose their normal biconcave shape and
become spherocytic with a decrease in surface to
volume ratio.
109

110. CLINICAL FEATURES
•Mild anaemia
•splenomegaly
• gallstones
•jaundice
•growth retardation.
110

111. INVESTIGATIONS
•Increased osmotic fragility of RBCs: RBCs when
exposed to a series of hypotonic saline solutions,
haemolyse at higher salt concentration than do
normal cells.
•Increase in MCHC.
111

112. INVESTIGATIONS
•Presence of spherocytes in the blood film
112

113. MANAGEMENT
1.Splenectomy
2. Daily penicillin V, 250 mg 12 hourly is prescribed
for at least 5 years following splenectomy.
3. Blood transfusion in severe haemolytic crises.
4. Folic acid 5 mg per day orally is prescribed to
support the increased erythropoiesis
113

114. SICKLE CELL DISEASE
•This is a haemolytic anaemia resulting from the
inheritance of a gene which causes an amino acid
substitution in the haemoglobin molecule (beta-6
glutamate → valine) creating HbS due to point
mutation.
•It is common in black Africans and their worldwide
descendants
114

115. CLASSIFICATION
1. Homozygote (SS)—sickle cell anaemia
2. Heterozygote (AS)—sickle cell trait
115

116. PATHOGENESIS
•In the deoxygenated state, the HbS molecules
polymerize and causes sickling of RBCs.
•Sickle cells are rigid, and haemolyse, and block
small vessels to cause infarction.
•Deoxygenated Hb align in parallel forming
tactoids that distort the RBC into the classic sickle
and oak leaf shaped cells.
116

117. CLINICAL FEATURES
•Anaemia
•reticulocytosis
• jaundice,
•painful swelling of hands and feet
•Splenomegaly in the early stages (later
autosplenectomy occurs can occur.
•Chronic ill-health
•renal failure
• bone necrosis
•Infection
•leg ulcers
117

118. INVESTIGATIONS
1. Peripheral smear: Shows Howell-Jolly bodies due
to auto splenectomy, target cells, nucleated RBCs,
RBC fragments, occasional thrombocytosis and
leukocytosis.
2. Hb electrophoresis at alkaline pH: HbS can be
detected by starch or agar gel electrophoresis.
118

119. INVESTIGATIONS
3.“Sickle Prep” test: This is performed by depriving
RBCs of oxygen using metabisulfite or dithionite
compounds as reducing agents and placing a
coverslip over a drop of blood on a glass side. The
RBCs sickle in situ.
119

120. MANAGEMENT
• Blood transfusion.
•Treatment of infection by antibiotics.
•Antisickling agents
•Hydroxyurea increases HbF to 14-15%
• Butyrate compounds increases HbF by increasing
number of erythroblasts expressing gamma
globin.
•Decibitane can elevate HbF.
•Folic acid 1 mg orally, daily.
•Pneumovax in functional asplenia.
•Gene therapy is under investigation
120

121. POLYCYTHEMIA
121

122. POLYCYTHAEMIA
•Polycythaemia signifies an increase in the number of
red blood cells above normal in the circulating
blood.
•In relative polycythaemia, the concentration of the
red cells becomes greater than normal (but total red
cell mass is normal) in the circulating blood. This
occurs as a result of loss of blood plasma.
• In absolute polycythaemia, there is an increase in
the total red cell mass. It is of two types:
122

123. POLYCYTHAEMIA
• In absolute polycythaemia, there is an increase in
the total red cell mass.
It is of two types:
• Primary polycythaemia
•unknown aetiology.
• This is associated with decreased EPO levels.
• Secondary polycythaemia
•known aetiology
•This is associated with increased EPO levels.
123

124. 124

125. POLYCYTHAEMIA VERA
Definition
• Polycythaemia vera is a clonal stem-cell disorder
characterised by an increased production of all
myeloid elements; however, the disease is generally
dominated by an elevated haemoglobin
concentration.
• Haematocrit >60 in males and >56 in females.
125

126. CLINICAL FEATURES
•headache, dizziness, vertigo, a sense of fullness
in the head, rushing in the ears, visual
disturbances, tinnitus, syncope and even chorea.
The patients often have a high colour, suffused
conjunctivae, deep red palate, dusky red hands
and retinal venous engorgement.
• Splenomegaly is very common
• Hepatomegaly occurs in 30% cases.
• Symptoms of peripheral vascular insufficiency,
and thrombotic and haemorrhagic complications.
126

127. 127

128. TREATMENT
• very slow course.
•Aim of therapy is to maintain haematocrit below
45 in males and 42 in females.
• Repeated venesection (phlebotomy) is the
treatment of choice.
• Low dose aspirin in all patients to reduce
thrombotic episodes.
128

129. DIAGNOSTICS
1. RED CELL COUNT
2. PHERIPHERAL FILM MORPHOLOGY
3. RED CELL FRAGILITY
4. PACKED CELL VOLUME
5. ESR
6. RED CELL INDICES
7. BLOOD GROUPING 129

130. RED CELL COUNT
•In adult males: 4.5–6 (average 5.2) millions per cu
mm of blood
•In adult females : 4–5.5 (average 4.7) millions per
cu mm of blood
•In newborns : 6–8 millions per cu mm of blood
•In children : 3–5 millions per cu mm of blood
130

131. PERIPHERAL FILM MORPHOLOGY
131

132. Peripheral Film Morphology
132

133. OSMOTIC FRAGILITY
•Lysis of red cells on exposure to different osmotic
solutions is called osmotic fragility.
•Osmotic fragility is defined as the ease with which the
red cells are ruptured when they are exposed to
hypotonic solutions.
• It assesses the integrity of red cell membrane.
•Interpretation: When the rate of hemolysis of red cells
is increased, the osmotic fragility is said to be
increased, and when the rate of hemolysis is decreased,
the osmotic fragility is said to be decreased
133

134. NORMAL VALUE AND VARIATIONS
Normally, osmotic fragility begins at 0.45 to 0.50 and
completes at 0.30 to 0.33.
Conditions of Diminished Fragility
• Iron deficiency anemia
• Thalassemia
• Sickle cell anemia
• Obstructive jaundice
• Post-splenectomy
Conditions of Increased Fragility
• Hereditary spherocytosis
• Congenital hemolytic anemia
134

135. PACKED CELL VOLUME
•Hematocrit or packed cell volume (PCV) is the
amount of packed red blood cells following
centrifugation.
• normal value
•Adult male : 46% (40–50%)
•Adult female : 42% (37–47%)
135

136. ERYTHROCYTE SEDIMENTATION
RATE
•The rate at which the red cells fall (sediment), is
known as the erythrocyte sedimentation rate (ESR).
•Factors Affecting ESR
• ESR depends on 3 major factors:
(1) The shape and number of red cells
(2) Size of rouleaux
(3) Plasma factors
136

137. NORMAL VALUES AND VARIATIONS
•In Wintrobe method:
• Males: 0–9 mm/hr
•Females : 0–20 mm/hr
•In Westergren method:
•Males: 3–5 mm/hr
• Females : 5–12 mm/hr
137

138. RED CELL INDICES
•Mean Corpuscular Volume
•Mean Corpuscular Hemoglobin
•Mean Corpuscular Hemoglobin Concentration
•Colour index
138

139. RED CELL INDICES
MEAN CORPUSCULAR VOLUME (MCV)
•Average volume of an RBC expressed in femtoliters
•MCV = Vol of packed red cells in ml per L of blood
Red cells in millions per μl of blood
• Normal range 78-94 fL
139

140. RED CELL INDICES
MEAN CORPUSCULAR HEMOGLOBIN
(MCH)
•Average weight of hemoglobin content in an RBC
expressed in picograms
•MCH = hemoglobin in grams per litre of blood
Red cells in millions per μl of blood
•Normal range 27-32 pg
140

141. RED CELL INDICES
MEAN CORPUSCULAR HEMOGLOBIN
CONCENTRATION (MCHC)
•is the amount of haemoglobin percentage in red cell
•MCHC =haemoglobin in g per dl of blood x 100
volume of packed cells in 100 ml of blood
Normal range 32-38 %
141

142. RED CELL INDICES
•COLOR INDEX (CI)
•CI = Haemoglobin Percentage
Red cell percentage
Normal range 0.85-1.15
142

143. BLOOD GROUPING
•The membrane of human RBCs contains a variety of
blood group specific antigens, also called
agglutinogens. More than 30 such antigens are
known but a few of them are of practical
significance. These antigens enable the blood group
of different individuals to be differentiated
143

144. THERAPEUTICS
•BLOOD TRANSFUSION
•Transfusion of whole blood or a component of blood
is common in medical practice. The common is the
transfusion of whole blood or red cell concentrates
that are required for the treatment of acute
hemorrhage or severe anemia
144

145. THERAPEUTICS
•EXCHANGE TRANSFUSION
• The treatment of newborns with severe anemia, jaundice and
hydrops is exchange transfusion soon after birth. Exchange
transfusion removes sensitized red cells, bilirubin and
maternal antibody from the plasma. A double-volume
exchange transfusion (2 x 80 ml/kg) replaces 90% of the
infant’s blood volume with antigen negative red cells. Blood
chosen for exchange should be ABO negative, Rh negative
and cross-matched against mother’s blood
145

146. RECENT ADVANCES
Erythrocytes as Carriers: From Drug Delivery to
Biosensors
erythrocytes can act as carriers that prolong the drug’s action due
to its gradual release from the carrier; as bioreactors with
encapsulated enzymes performing the necessary reactions, while
remaining inaccessible to the immune system and plasma
proteases; or as a tool for targeted drug delivery to target organs,
primarily to cells of the reticuloendothelial system, liver and
spleen. To date, erythrocytes have been studied as carriers for a
wide range of drugs, such as enzymes, antibiotics, anti-
inflammatory, antiviral drugs, etc., and for diagnostic purposes
(e.g., magnetic resonance imaging). The review focuses only on
drugs loaded inside erythrocytes, defines the main lines of
research for erythrocytes with bioactive substances, as well as the
advantages and limitations of their application. Particular
attention is paid to in vivo studies, opening-up the potential for
the clinical use of drugs encapsulated into erythrocyte
146

147. REFERENCES
• Guyton and Hall textbook of medical Physiology 14th Edition
• Ganong’s Review of Medical Physsiology 26th Edition
• Wintrobe’s Clinical Hematology 3rd Edition
• Comprehensive textbook of Medical Physiology GK Pal
• Best and Taylor ‘s Physiological Basis Of Medical Practice 13th Edition
• Medical Physiology Boron and Boulpaep 2nd Edition
• Harrison’s Manual of medicine 19th Edition
• Manual of Practical Medicine R Alagappan
• Manual of practical physiology
• History of physiology RK marya
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7151026/#:~:text=T
he%20targeted%20delivery%20of%20drugs,treat%20tumors%20of%
20these%20tissues.
147