Microcytic anaemia Flashcards

1
Q

What is anaemia

A

reduced red blood cell mass

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2
Q

How is red blood cell mass measured?

A

Haemoglobin concentration is surrogate (indicator) of red blood cell mass

Haematocrit

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3
Q

What is haematocrit

A

percentage of total blood volume that consists of red cells

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4
Q

In what scenarios are haemoglobin concentration and haematocrit poor marker of anaemia?

A

rapid blood volume loss (bleeding) - Hb and Hct will be same

plasma expansion (IV fluids) - Hct will be decreased but Hb will be the same

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5
Q

How is Hb concentration measured?

A

red cells are burst to form haemoglobin solution

haemoglobin is stabilised and then the optical density is measured

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6
Q

What are reticulocytes

A

immature red cells that have just been formed in the bone marrow

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7
Q

describe reticulocytes

A

large, stain purple or deep red
contain RNA
polychromasia of blood film results from RNA in reticulocytes

reticulocytosis occurs in response to anaemia

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8
Q

What is MCV

A

mean cell volume (volume of red cell)

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9
Q

What are the causes of anaemia

A

decreased production

increased loss or destruction

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10
Q

How is decreased production identified

A

low reticulocyte count

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11
Q

What causes decreased production of red cells

A

hypoproliferative (reduced erythropoiesis)

maturation abnormality (erythropoiesis ineffective)

  • impaired haemoglobinisation
  • impaired cell division
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12
Q

What are some causes of increased loss or destruction of red cells

A

haemolysis

bleed / haemorrhage

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13
Q

How is increased loss or destruction identified

A

High reticulocyte count

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14
Q

What is the difference between microcytic and macrocytic anaemia

A

microcytic - low MCV (consider problem with haemoglobinisation

macrocytic - high MCV (consider problem with maturation)

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15
Q

Where does haemoglobin synthesis occur?

A

cytoplasm

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16
Q

What is required for haemoglobin synthesis

A

Haem and globin

17
Q

What does haem group consist of?

A

haem group is porphyrin ring containing Fe2+ and protoporphyrin

18
Q

What effect does defect in cytoplasmic synthesis of haemoglobin have on cell size?

A

results in small cells with low Hb content

cells are microcytic (small) and hypochromatic

19
Q

What is the microcytic, hypochromatic anaemia due to

A

deficient haemoglobin synthesis - a cytoplasmic defect

20
Q

What are some causes of deficient haemoglobin synthesis and thus microcytic, hypochromatic anaemia

A
Iron defficiency (from dietry intake)
chronic disease (normal body iron but lack of available iron)

Problem with porphyrin synthesis - lead poisoning (very rare)
Globin defficiency - thalassaemia

Mostly due to iron defficiency or thalassaemia

21
Q

in what two states can iron exist and what is it used for in the body

A

Fe2+ Fe3+

used to transport oxygen and also in mitochondrial production of ATP

22
Q

why is iron toxic

A

creates free radicals

23
Q

Where is most iron stored in the body?

A

in haemoglobin (2500mg)

24
Q

where else is iron stored in the body?

A

in liver (500mg) and in macrophages (500mg)

25
Q

What molecule is iron stored in? and how many molecules of iron can it store?

A

Ferritin can store 4000 molecules of iron

26
Q

What molecule is iron transported in?

A

Transferrin

27
Q

What do you measure to measure Iron stores in the body

A

Ferritin count

low ferritin means iron deficiency

28
Q

What will you see in iron deficiency anaemia

A

microcytic, hypochromatic anaemia

low serum ferritin

29
Q

What does transferring do?

A

transports iron from donors (macrophages in bone marrow, hepatocytes etc) to tissues expressing transferrin receptors

30
Q

What are some causes of iron deficiency

A

not eating enough in diet
losing too much (bleeding - usually GI)
not absorbing enough (coeliac)

31
Q

what are some consequences of negative iron balance

A

exhaustion of iron stores
iron deficient erythropoiesis (decreased in MCV)
microcytic hypochromatic anaemia
skin changes, koilonychia