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Haematology and Transfusion > Microcytic and macrocytic anaemia > Flashcards

Microcytic and macrocytic anaemia Flashcards

1
Q

What is the definition of anaemia?

A

A reduction of Haemoglobin concentration of the blood below the normal range for age and sex.

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2
Q

What are the male and female refence ranges for anaemia?

A
  • Male - 13.3-16.7 g/dL
  • Female – 11.8 – 14.8 g/dL
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3
Q

What are thee general signs and symptoms of anaemia?

A

Pallor of the conjunctival mucosa (a) and of the nail bed (b) Retinal haemorrhages (c) caused by severe anaemia.

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4
Q

What are the normal values for blood cells and haematinics?

A
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5
Q

What does leukocyte and platelet counts help distinguish between?

A

Pure anaemia and ‘pancytopenia’

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6
Q

A high reticulocyte count is indicative of

A

anaemia

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7
Q

What are the indicators of microcytic, hypochromic anaemia?

A
  • MCV<80FL, MCH <27 pg
  • Iron deficiency Thalassaemia
  • Lead poisoning
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8
Q

What are the indicators of normocytic, normochromic anaemia?

A
  • MCV 80-95fl, MCH> 27pg
  • Haemolytic anaemia
  • Chronic anaemia
  • Renal disease
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9
Q

What are the indicators of macrocytic anemia?

A
  • MCV>95fl
  • Vitamin B12 or folate deficiency
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10
Q

What is examination is essential in all cases of anaemia?

A

Blood film examination

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11
Q

What may reveal different anaemia’s?

A

Abnormal red cell size (anisocytosis) and shape (poikilocytosis)

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12
Q

What are the causes of red cell abnormalities?

A
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13
Q

What red cell inclusions may be seen in the peripheral blood film in various conditions?

A
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14
Q

What are the causes of microcytic anaemia?

A
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15
Q

What are the features of iron deficiency anaemia?

A
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16
Q

Iron is provided by dietary sources such as

A

liver, meat, sea foods, eggs, vegetables and dried foods.

•May present a problem in food absorption

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17
Q

How much iron do people need?

A
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18
Q

What is microcytic, hypochromic anaemia?

A
  • Disorder of haem eg iron deficiency or malignancy
  • Disorder in synthesis of globin eg thalassemia
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19
Q

Give a summary of iron cycling in a healthy individual

A
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20
Q

Describe iron uptake, storage and utilization for Hb synthesis

A
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21
Q

When the rate of iron absorption from diet is low, the body uses iron in stores causing

A

a negative balance

22
Q

Stores become depleted =

A

latent deficiency

23
Q

What are the causes of depletion of iron level stores

A

Causes:

  1. Increased requirement (bleed/pregnancy/puberty)
  2. Decreased supply of iron
24
Q

Compare latent iron deficiency and iron deficiency anaemia

25
Q

What are the laboratory findings in iron deficiency anaemia?

A

FBC and Blood film

Low Hb, Red Cell count, MCH, MCV

  1. Microcytosis= small red blood cells
  2. Hypochromia= pale red blood cells
  3. Elliptocytosis= long thin cells
  4. Tear drop poikilocytes= tear shaped cells
  5. Anisocytosis= red blood cells are unequal in size

Anaemia is Microcytic and Hypochromic

Can also investigate Serum Ferritin – main storage protein of iron

–Remember! (Acute phase protein)

26
Q

What laboratory findings indicate microcytic and hypochromic anaemia

A

Microcytic and hypochromic

  • Smaller cells
  • Large centre of pallor
  • Low HB
  • Pencil cells –classic finding of IDA
27
Q

What would you see on a normal blood film?

A
  • Normal RBC’s.
  • Uniform
  • More pigmented
  • Zone of central pallor about 1/3 the size of the RBC
28
Q

What are the treatments for anaemia?

A
  • Iron supplements
  • The most commonly prescribed supplement is ferrous sulphate twice daily
  • In severe cases - blood transfusion & iron therapy
  • Vitamin C
  • Birth control pills
29
Q

Show a dimorphic blood film in IDA responding to iron therapy

A

2 population of RBCs present; microcytic and hypochromic and the other normocytic and well haemaglobinised

30
Q

What is macrocytic anaemia?

A
  • RBCs are abnormally large (MCV >98fL)
  • Many causes but can be subdivided into megaloblastic and non-megaloblastic anaemia
  • Based on the appearance of developing erythroblasts in the bone marrow
31
Q

What are the causes of macrocytic anaemia?

32
Q

What are the sources of B12 (cobalamin)

A

Food source

Vitamin B12 content (μg)

Beef liver, 3.5 oz ⇢48

Rainbow trout, wild, 3.0 oz ⇢5.4

Salmon, 3.0 oz ⇢4.9

Beef, 3.0 oz ⇢2.4

Tuna, white, 3.0 oz ⇢1.0

Yogurt, plain, 1 cup ⇢1.4

Fortified cereal ⇢6.0

Milk, 1 cup ⇢0.9

Swiss cheese, 1 oz ⇢0.9

Egg, 1 whole ⇢0.6

33
Q

What is the RDA for B12

34
Q

How is B12 synthesised and where is it found in the body?

A
  • Synthesized exclusively by microorganisms
  • Found in the liver of animals bound to protein known as methycobalamin
  • To be absorbed the vitamin B12 present in foodstuffs must be liberated and extracted by the combination of the proteolytic enzyme pepsin and the acid environment of the stomach

THIS TYPE OF ANAEMIA AFFECTS VEGETARIANS

35
Q

Vitamin B12 is an essential cofactor of 2 enzymes:

A

a) Conversion of L-methylmalonyl co-enzyme A to succinyl co-enzyme A
b) Methylation of homocysteine to methionine

36
Q

Give a summary of B12 absorption

A
  1. B12 complexes with intrinsic factor (IF) 1:1
  2. Intrinsic factor (IF) acts as a carrier protein by delivering B12 to the Large intestine where it can be absorbed by the ileum
  3. For absorption to occur, docks to receptor on an enterocyte (cubulin, megalin and amnionless)
  4. Directs endocytosis of the IF-B12 complex in the distal ileum where B12 is absorbed and intrinsic factor is destroyed
37
Q

Describe B12 transport

A

Transcobalamin and Haptocorrin

38
Q

What are the 2 main causes of vitamin B12 deficiency?

A

1.Malnutrition

Inadequate dietary intake– vegan diet- uncommon

2. Malabsorption

–90% of cases lack of intrinsic factor – Pernicious Anaemia.

–Gastrointestinal disease–Surgical removal on site of IF synthesis

–Drug Induced

–Increased requirement of vitamin- pregnancy

39
Q

What is pernicious anaemia

A
  • Immune system attacks the cells in the stomach that produce the intrinsic factor, which means body in unable to absorb vitamin B12
  • Usual onset 60 years
  • Helicobacter pylori infection may initiate an autoimmune gastritis which presents in younger individuals as iron deficiency and in elderly as pernicious anaemia
  • 1:10,000 in northern Europe••Treated with B12 injections
40
Q

Describe the lab diagnosis of B12 deficiency

41
Q

What are the sources of folate?

42
Q

Folate vs vitamin B12

43
Q

What are the causes of folate deficiency?

A
  1. Inadequate dietary intake (common), folate is heat labile.
  2. Intestinal malabsorption

Coeliac disease- destruction of intestinal villi= malabsorption of folate

3. Increased requirement

Pregnancy

  1. Drug induced interferes with absorption or metabolism

Alcohol (coupled with poor diet)

Methotrexate

  1. inhibits dihydrofolate reductase= decreased supply of folates
  2. .Folate aids those treated with long-term, low-dose methotrexate for rheumatoid arthritis (RA) or psoriasis
44
Q

Why are large cells produced in macrocytic anaemia?

A
  • Folate necessary for nucleotides (AMP/GMP)
  • Retardation of DNA synthesis
  • Inhibition of rate limiting step
45
Q

Folate function

45
Q

Folate necessary for

46
Q

Biochemical basis of megaloblastic anaemia

A
  • •Inadequate amounts of (dUMP)/ (dTMP) leads to a failure of DNA synthesis

•Loss of nucleus in cells with fewer cell divisions leads to larger cells

47
Q

megaloblastic anaemia:

FBC and Blood Film

A

Reduced Hb,

increased MCV (>100)

MCH= (HYPERCHROMIC)

Macrocytosis= decreased number of cell divisions before loss of nucleus of the cell and release into the circulation

  • Megaloblasts
  • Poikilocytes
  • anisocytosis

Hypersegmented neutrophils- 7-8 lobes instead of 2-5 lobes= DNA defect & structural abnormalities in nuclear chromatin

Low levels of serum B12

Low levels of serum and red cell folate

Presence of autoantibodies to intrinsic factor/gastric parietal cells- Pernicious anaemia

48
Q

Closer look at macrocytic blood film

49
Q

Macrocytic anaemia diagnosis

Haematology and Transfusion (4 decks)

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