hematology lecture of megaloblastic anemia

1. MCQs

2. MCQ
1
• Hypoproliferative anaemias include all
except ___.
A. Iron Deficiency Anaemia
B. Anaemia due to chronic inflammation
C. Sickle Cell Anaemia
D. Sideroblastic Anaemia

3. MCQ
2
• Transport of Iron across brush border
intestinal cell is facilitated by ___.
A. Ferroportin
B. Nramp 2
C. DMT 1
D. Both B & C

4. MCQ
3
• The earliest sign of Iron deficiency
anemia is ___.
A. Increase in TIBC
B. Decrease in serum Iron
C. Decrease in serum ferritin
D. Increase in red cell protoporphyrin

5. MCQ
4
• Which of the following is false regarding
the stage of negative iron balance in
IDA?
A. Bone marrow stainable iron decreases
B. TIBC decreases
C. RBC morphology normal
D. Serum Iron Normal

6. MCQ
5
• A 28 year old female with fatiguability is
evaluated to have Hb – 6g/dL, MCV –
67fL, MCH – 24pg, and elevated RDW.
The most likely diagnosis is ___.
A. Thalassemia
B. Megaloblastic Anaemia
C. Iron Deficiency Anaemia
D. Hypothyroidism

7. MCQ
6
• The red blood cell indices of a 56 year
old male patient with a Hb of 9g/dL are
as follows: MCV = 112 fL and MCHC =
34 g/dL. Which of the following is the
most likely diagnosis?
A. Folate deficiency
B. Sideroblastic anemia
C. Beta-thalassemia
D. Iron deficiency anaemia

8. MCQ
7
• 58-Co labeled cobalamin was
administered to a 65-yr-old female. 24-hr
urinary excretion of radiolabeled
cobalamin was found to be less than
10%. Which of the following conditions is
the most likely diagnosis?
A. Perinicious Anemia
B. Chronic Pancreatitis
C. Both A & B
D. NORMAL individual

9. MCQ
8
• Monoglutamates of dietary folate are
absorbed from ___?
A. Upper small intestine
B. Mid-small intestine
C. Terminal illeum
D. Ascending colon

10. MCQ
9
• A 30-yr-old female with a past medical history
of generalized seizures controlled with
phenytoin therapy. She had mild pallor on
physical examination. Lab values reveal Hb –
9.8g/dL, MCV – 106 fL, Platelets –
1,80,000/cu.mm, leukocytes – 7800/cu.mm.
Which of the following supplementations could
have prevented this anemia?
A. Iron
B. Vitamin B12
C. Vitamin B6
D. Folic Acid

11. MCQ
10
• A patient with megaloblastic anemia was
treated with folate supplements. The patient’s
signs of anemia resolved but the patient
continued to complain of poor memory,
numbness and tingling in the extremities. You
suspect that the patient was originally
misdiagnosed. Which of the following will
correct the patient’s underlying condition?
A. Injection Hydroxycobalamin
B. Higher doses of Folic Acid
C. Chelation therapy
D. Thiamine supplementation

12. ANSWERS & EXPLANATION

13. MCQ
1
• Hypoproliferative anaemias include all
except ___.
A. Iron Deficiency Anaemia
B. Anaemia due to chronic inflammation
C. Sickle Cell Anaemia
D. Sideroblastic Anaemia

14. MCQ
1

15. MCQ
2
• Transport of Iron across brush border
intestinal cell is facilitated by ___.
A. Ferroportin
B. Nramp 2
C. DMT 1
D. Both B & C

16. MCQ
2

17. MCQ
3
• The earliest sign of Iron deficiency
anemia is ___.
A. Increase in TIBC
B. Decrease in serum Iron
C. Decrease in serum ferritin
D. Increase in red cell protoporphyrin

18. MCQ
3

19. MCQ
4
• Which of the following is false regarding
the stage of negative iron balance in
IDA?
A. Bone marrow stainable iron decreases
B. TIBC decreases
C. RBC morphology normal
D. Serum Iron Normal

20. MCQ
4

21. MCQ
5
• A 28 year old female with fatiguability is
evaluated to have Hb – 6g/dL, MCV –
67fL, MCH – 24pg, and elevated RDW.
The most likely diagnosis is ___.
A. Thalassemia
B. Megaloblastic Anaemia
C. Iron Deficiency Anaemia
D. Hypothyroidism

22. MCQ
5
Low MCV (N: 87-96 fL) and Low MCH
(N: 27-33 pg) with an elevated RDW is
suggestive of Iron Deficiency Anemia.
• Microcytic Hypochromic anemia is
seen in both IDA and thalassemia.
• However, RDW index is small (normal)
in thalassemia and elevated in IDA.
Also, serum iron levels and transferrin
saturation is normal in thalassemia.
• Hypothyroidism and megaloblastic
anemia show macrocytosis.

23. MCQ
6
• The red blood cell indices of a 56 year
old male patient with a Hb of 9g/dL are
as follows: MCV = 112 fL and MCHC =
34 g/dL. Which of the following is the
most likely diagnosis?
A. Folate deficiency
B. Sideroblastic anemia
C. Beta-thalassemia
D. Iron deficiency anaemia

24. MCQ
6
• Folate deficiency presents with
macrocytic (Raised MCV, N: 80-100 fL)
and normochromic (Normal MCHC, N:
33-36 g/dL) anemia.
• Also characterized by increased MCH,
RDW is elevated in two-thirds of all
cases. The reticulocyte count is
decreased due to destruction of fragile
and abnormal megaloblastic erythroid
precursors.
• Other options listed are classified as
microcytic hypochromic anemia.

25. MCQ
7
• 58-Co labeled cobalamin was
administered to a 65-yr-old female. 24-hr
urinary excretion of radiolabeled
cobalamin was found to be less than
10%. Which of the following conditions is
the most likely diagnosis?
A. Perinicious Anemia
B. Chronic Pancreatitis
C. Both A & B
D. NORMAL individual

26. MCQ
7
• Schilling test is abnormal in perinicious
anemia, chronic pancreatitis, bacterial
overgrowth and illeal disease.
• Schilling test is done to determine the
cause of cynocobalamin deficiency.
• Schilling test is normalised by adding
intrinsic factor in perinicious anemia,
pancreatic enzymes in chronic
pancreatitis and a 5-day antibiotic course
in bacterial overgrowth.

27. MCQ
8
• Monoglutamates of dietary folate are
absorbed from ___?
A. Upper small intestine
B. Mid-small intestine
C. Terminal illeum
D. Ascending colon

28. MCQ
8
• Dietary folates are rapidly absorbed from
the upper small intestine in the form of
monoglutamates.
• Vitamin B12 absorption takes place in
the terminal illeum.

29. MCQ
9
• A 30-yr-old female with a past medical history
of generalized seizures controlled with
phenytoin therapy. She had mild pallor on
physical examination. Lab values reveal Hb –
9.8g/dL, MCV – 106 fL, Platelets –
1,80,000/cu.mm, leukocytes – 7800/cu.mm.
Which of the following supplementations could
have prevented this anemia?
A. Iron
B. Vitamin B12
C. Vitamin B6
D. Folic Acid

30. MCQ
9
• This patient has mild megaloblastic
anemia (high MCV), probably due to
chronic phenytoin therapy.
• Some anti-epileptic drugs like phenytoin,
phenobarbital can cause megaloblastic
anemia by impairing the absorption of
folate in the small intestine.
• Folic acid supplementation can prevent
this condition.

31. MCQ
10
• A patient with megaloblastic anemia was
treated with folate supplements. The patient’s
signs of anemia resolved but the patient
continued to complain of poor memory,
numbness and tingling in the extremities. You
suspect that the patient was originally
misdiagnosed. Which of the following will
correct the patient’s underlying condition?
A. Injection Hydroxycobalamin
B. Higher doses of Folic Acid
C. Chelation therapy
D. Thiamine supplementation

32. MCQ
10
• The patient’s underlying condition is Vitamin B12
deficiency.
• Administration of Folic Acid can partially reverse
some of the hematologic abnormalities associated
with vitamin B12 deficiency. However, the
neurologic manifestations of vitamin B12
deficiency are not treated by folic acid.
• Administration of folic acid to an individual with
vitamin B12 deficiency can potentially mask
untreated B12 deficiency or even worsen the
neurologic complications.
• Lead poisoning can cause neurologic symptoms
but is associated with microcytic anemia.

33. MEGALOBLASTIC ANAEMIA
Dr. Vivek Veeram Reddy

34. DEFINITION

35. • This results from a deficiency of vitamin
B12 or folic acid,
• or from disturbances in cobalamin or folic
acid metabolism.

36. OTHER
CAUSES
• Therapy with antifolate drugs (e.g.,
methotrexate)
• Independent of either cobalamin or folate
deficiency and refractory to cobalamin and
folate therapy:
Some cases of acute myeloid leukemia,
myelodysplasia
Therapy with drugs interfering with synthesis of DNA
(e.g., cytosine arabinoside, hydroxyurea, 6-
mercaptopurine, azidothymidine [AZT])
Orotic aciduria (responds to uridine)
Thiamine-responsive

37. PATHOPHYSIOLOGY

38. • Folate is an important substrate of, and
vitamin B12 a co-factor for, the
generation of the essential amino acid
methionine from homocysteine.
• This reaction produces tetrahydrofolate,
which is converted to thymidine
monophosphate for incorporation into
DNA.
• Deficiency of either vitamin B12 or folate
will therefore produce high plasma levels
of homocysteine and impaired DNA
synthesis.

40. • The end result is cells with arrested
nuclear maturation but normal
cytoplasmic development: so-called
nucleocytoplasmic asynchrony.
• All proliferating cells will exhibit
megaloblastosis; hence changes are
evident in the buccal mucosa, tongue,
small intestine, cervix, vagina and uterus.

41. • Cells become arrested in development
and die within the marrow; this ineffective
erythropoiesis results in an expanded
hypercellular marrow.
• The megaloblastic changes are most
evident in the early nucleated red cell
precursors, and haemolysis within the
marrow results in a raised bilirubin and
LDH, but without the reticulocytosis
characteristic of other forms of
haemolysis.

43. • The mature red cells are large and oval, and
sometimes contain nuclear remnants.
• Nuclear changes are seen in the immature
granulocyte precursors and a characteristic
appearance is that of ‘giant’ metamyelocytes
with a large ‘sausage-shaped’ nucleus.
• The mature neutrophils show
hypersegmentation of their nuclei, with cells
having six or more nuclear lobes.
• If severe, a pancytopenia may be present in
the peripheral blood.

45. VITAMIN B12

46. VITAMIN B12 - METABOLISM

47. • DIETARY INTAKE
• ABSORPTION
• TRANSPORT
• STORAGE
• UTILIZATION

48. DIETARY
INTAKE
• The average daily diet contains 5–30 μg
of vitamin B12, mainly in meat, fish, eggs
and milk – well in excess of the 1 μg daily
requirement.

49. ABSORPTION
• In the stomach, gastric enzymes release
vitamin B12 from food and at gastric pH
it binds to a carrier protein termed R
protein.
• The gastric parietal cells produce
intrinsic factor, a vitamin B12- binding
protein which optimally binds vitamin B12
at pH 8.

50. ABSORPTION
• As gastric emptying occurs, pancreatic
secretion raises the pH and vitamin B12
released from the diet switches from the
R protein to intrinsic factor.

51. ABSORPTION
• Bile also contains vitamin B12 which is
available for reabsorption in the
intestine.
• The vitamin B12–intrinsic factor complex
binds to specific receptors in the
terminal ileum, and vitamin B12 is
actively transported by the enterocytes to
plasma.

52. TRANSPORT
• It binds to transcobalamin II, a
transport protein produced by the liver,
which carries it to the tissues for
utilisation.

54. STORAGE
• The liver stores enough vitamin B12 for
3 years and this, together with the
enterohepatic circulation, means that
vitamin B12 deficiency takes years to
become manifest, even if all dietary
intake is stopped or severe B12
malabsorption supervenes.

55. UTILIZATION

56. CAUSES OF VITAMIN B12
DEFICIENCY

57. • DIETARY DEFICIENCY
• GASTRIC PATHOLOGY
• PERNICIOUS ANEMIA
• SMALL BOWEL PATHOLOGY

58. DIETARY
DEFICIENCY
• This only occurs in strict vegans but the
onset of clinical features can occur at any
age between 10 and 80 years.

59. GASTRIC
PATHOLOGY
• Hypochlorhydria in elderly patients
• Total gastrectomy invariably results in
vitamin B12 deficiency within 5 years,
• Often combined with iron deficiency
• 10-20% patients with Partial gastrectomy

60. PERNICIOUS
ANEMIA
• Organ-specific autoimmune disorder in
which the gastric mucosa is atrophic, with
loss of parietal cells causing intrinsic
factor deficiency.
• Less than 1% of dietary vitamin B12 is
absorbed.
• More common with other autoimmune
disease
• Anti-intrinsic factor antibodies in the
context of B12 deficiency is diagnostic
• Antiparietal cell antibodies are present in
over 90% of cases
• Schilling test

61. SMALL
BOWEL
PATHOLOGY
• Pancreatic exocrine insufficiency –
chronic pancreatitis
• Motility disorders or
hypogammaglobulinaemia can result in
bacterial overgrowth
• Fish tapeworm infestation
• Inflammatory disease of the terminal
ileum, such as Crohn’s disease
• Surgery on that part of the bowel.

62. FOLATE

63. FOLATE - METABOLISM

64. • DIETARY INTAKE
• ABSORPTION
• TRANSPORT
• STORAGE
• UTILIZATION

65. DIETARY
INTAKE
• Folates are produced by plants and
bacteria; hence dietary leafy vegetables
(spinach, broccoli, lettuce), fruits
(bananas, melons) and animal protein
(liver, kidney) are a rich source.
• An average Western diet contains more
than the minimum daily intake of 50 μg
but excess cooking destroys folates.
Most dietary folate is present as
polyglutamates.

66. ABSORPTION
• Polyglutamates are converted to
monoglutamate in the upper small
bowel and actively transported into
plasma.

67. TRANSPORT
&
STORAGE
• Plasma folate is loosely bound to plasma
proteins such as albumin and there is an
Enterohepatic circulation.
• Total body stores of folate are small
and deficiency can occur in a matter of
weeks.

68. UTILIZATION

69. CAUSES OF FOLATE
DEFICIENCY

70. Diet
• Poor intake of vegetables
Malabsorption
• e.g. Coeliac disease
Increased demand
• Cell proliferation, e.g. haemolysis
• Pregnancy
Drugs
• Certain anticonvulsants (e.g. phenytoin)
• Contraceptive pill
• Certain cytotoxic drugs (e.g. methotrexate)

71. • The edentulous elderly or psychiatric patient is
particularly susceptible to dietary deficiency and
this is exacerbated in the presence of gut
disease or malignancy.
• Pregnancy-induced folate deficiency is the most
common cause of megaloblastosis worldwide
and is more likely in the context of twin
pregnancies, multiparity and hyperemesis
gravidarum.

72. CLINICAL FEATURES OF
MEGALOBLASTIC ANAEMIA

73. SYMPTOMS
• Malaise (90%)
• Breathlessness (50%)
• Paraesthesiae (80%)
• Sore mouth (20%)
• Weight loss
• Altered skin pigmentation
• Impotence
• Poor memory
• Depression
• Personality change
• Hallucinations
• Visual disturbance

74. SIGNS
• Smooth tongue
• Angular cheilosis
• Vitiligo
• Skin pigmentation
• Heart failure
• Pyrexia

75. NEUROLOGICAL
MANIFESTATIONS OF VITAMIN
B12 DEFICIENCY

76. PATHOPHYSIOLOGY
• The main pathological finding is focal
demyelination affecting the spinal cord,
peripheral nerves, optic nerves and
cerebrum.
• The most common manifestations are
sensory, with peripheral paraesthesiae
and ataxia of gait.

77. FINDINGS
Peripheral nerves
• Glove and stocking paraesthesiae
• Loss of ankle reflexes
Spinal cord
• Subacute combined degeneration of the cord
Posterior columns – diminished vibration
sensation and proprioception
Corticospinal tracts – upper motor neuron signs
Cerebrum
• Dementia
• Optic atrophy
Autonomic neuropathy

78. INVESTIGATIONS

79. MEGALOBLASTIC
ANEMIA

80. VITAMIN
B12
DEFICIENCY
Serum Cobalamin Levels - decreased
Special Investigations
• Serum Methylmalonate & Homocysteine
- raised
• Serum Gastrin - raised
• Gastric Endoscopy
• Anti bodies against intrinsic factor and
parietal cells - elevated
• Intestinal Endoscopy (Colonoscopy)

81. FOLATE
DEFICIENCY
Diagnostic findings
• Serum folate levels may be low but are difficult
to interpret
• Low red cell folate levels indicate prolonged
folate deficiency and are probably the most
relevant measure
Corroborative findings
• Macrocytic dysplastic blood picture
• Megaloblastic marrow

82. MANAGEMENT

83. MEGALOBLASTIC
ANEMIA
• If severe angina or heart failure is
present, transfusion can be done.
• The volume load imposed by transfusion
may result in decompensation and
severe cardiac failure.
• In such circumstances, exchange
transfusion or slow administration of 1
U of red cells with diuretic cover may be
given cautiously.

84. VITAMIN
B12
DEFICIENCY
• Hydroxycobalamin 1000 μg IM for 6
doses 2 or 3 days apart, followed by
maintenance therapy of 1000 μg every 3
months for life.
• Reticulocyte count will peak by the 5th–
10th day.
• The haemoglobin will rise by 0.1g/mL
every week.
• A sensory neuropathy may take 6–12
months to correct; long-standing
neurological damage may not improve.

85. DIMORPHIC
ANEMIA
• The response of the marrow is
associated with a rapid depletion of iron
stores.
• If an initial response is not maintained
and the blood film is dimorphic (i.e.
shows a mixture of microcytic and
macrocytic cells), the patient may need
additional iron therapy.

86. FOLATE
DEFICIENCY
• Oral folic acid 5 mg daily for 3 weeks
will treat acute deficiency
• 5 mg once weekly is adequate
maintenance therapy.
• Supraphysiological supplementation (400
μg/day) can reduce the risk of coronary
and cerebrovascular disease by
lowering plasma homocysteine levels.

87. FOLATE
PROPHYLAXIS
• Prophylactic folic acid in pregnancy
prevents megaloblastosis in women at
risk, and reduces the risk of fetal neural
tube defects.
• Prophylactic supplementation is also
given in chronic haematological
disease associated with reduced red cell
lifespan.

88. THANK YOU