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Haematology > Anaemia and Microcytic Anaemia > Flashcards

Anaemia and Microcytic Anaemia Flashcards

1
Q

What is anaemia?

A

Reduced total red cell mass = Hb < 130g/l in men and < 120g/l in women

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2
Q

Why are surrogate markers needed for red cell mass?

A

It is difficult to measure in routine practice

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3
Q

What are some surrogate markers of red cell mass?

A

Hb concentration and haematocrit

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4
Q

What method is used to measure Hb concentration?

A

The spectrophotomeric method

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5
Q

What is the spectrophotomeric method for measuring Hb concentration?

A

Burst red cells to create Hb solution
Stabilise Hb molecules
Measure optical density at 540nm

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6
Q

Why is optical density measured when calculating Hb concentration?

A

It is proportional to the concentration of Hb = Beer’s law

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7
Q

How is Hb concentration calculated?

A

Against the known reference standard cyan-metHb concentration solution

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8
Q

What is haematocrit?

A

Ratio or percentage of whole blood that is red cells if the sample was left to settle

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9
Q

How do modern machines calculate haematocrit?

A

By adding the calculated volume of the red cells it counts

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10
Q

What is the body’s response to anaemia?

A

To increase red cell production via reticulocytes

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11
Q

What are reticulocytes?

A

Red cells that have just left the bone marrow = larger than average red cells

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12
Q

Why do reticulocytes stain purple/deeper red?

A

They still have remnants of RNA

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13
Q

How do reticulocytes appear on a blood film?

A

Polychromatic

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14
Q

How are reticulocytes involved in the body’s response to anaemia?

A

Reticulocyte production is up-regulated by bone marrow = process takes a few days

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15
Q

What information do automatic analysers give about red cells?

A

Red cell size and light scattering properties = results are rapid and reproducible

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16
Q

What are the measured red cell indices?

A

Hb concentration, number of red cells (concentration), size of red cells (MCV)

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17
Q

What are the calculated red cell indices?

A

Haematocrit, mean cell Hb, mean cell Hb concentration

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18
Q

What do blood films assess?

A

Look at cellular morphology

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19
Q

What does reticulocyte count assess?

A

Marrow response

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20
Q

How is anaemia classified?

A

Pathophysiology or morphological characteristics

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21
Q

What are the pathophysiological classifications of anaemia?

A 
Decreased production (low reticulocyte count)
Increased loss or destruction of red cells (high reticulocyte count)
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22
Q

What are some causes of decreased production of red cells?

A

Hypoproliferative = reduced amount of erythropoiesis

Maturation abnormality = erythropoiesis present but ineffective

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23
Q

What are maturation abnormalities split into?

A

Cytoplasmic defects = impaired haemoglobinisation

Nuclear defects = impaired cell division

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24
Q

What are some causes of increased red cell loss or destruction?

A

Bleeding or haemolysis

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25
Q

What is mean cell volume (MCV) useful for?

A

Distinguishing between cytoplasmic and nuclear defects

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26
Q

What does a low MCV indicate?

A

Microcytic = consider problems with haemoglobinisation (cytoplasmic)

27
Q

What does a high MCV indicate?

A

Macrocytic = consider problems with maturation (nuclear)

28
Q

Where does Hb synthesis occur?

A

In the cytoplasm = defects result in small cells

29
Q

What is needed to synthesis Hb?

A

Heme and globins = shortage in these results in small red cells with a low Hb content

30
Q

How do cells with a low concentration of Hb appear?

A

Microcytic and hypochromatic

31
Q

What is the underlying pathology of hypochromatic microcytic anaemia?

A

Deficient haemoglobin synthesis as a result of a cytoplasmic defect

32
Q

What are some causes of hypochromatic microcytic anaemia?

A

Heme deficiency or globin deficiency

33
Q

What are some causes of heme deficiency?

A

Lack of iron for erythropoiesis
Problems with porphyrin synthesis = rare
Congenital sideroblastic anaemia = very rare

34
Q

What are some reasons for there being a lack of iron for erythropoiesis?

A

Iron deficiency = low body iron

Some cases of anaemia of chronic disease = normal body iron but lack of available iron

35
Q

What are some examples of problems with porphyrin synthesis?

A

Lead poisoning and pyridoxine responsive anaemias

36
Q

What is an example of a cause of globin deficiency?

A

Thalassaemia

37
Q

How does iron exist in the body?

A

As Fe2+ or Fe3+

38
Q

What is iron used for in the body?

A

Essential for oxygen and electron transport

39
Q

Why does iron need to be handled carefully in the body?

A

It is potentially toxic and can generate free radicals

40
Q

What kind of system is iron metabolism?

A

Closed system = only able to absorb small amounts of iron

41
Q

Where is iron transferred to from its storage site?

A

The marrow

42
Q

Where does iron turnover take place?

A

In the plasma pool = fast process

43
Q

What form is iron stored in?

A

Stored as ferritin = mainly found in liver

44
Q

What is circulating iron bound to?

A

Transferrin

45
Q

Where does transferrin transfer iron to?

A

Bone marrow = transfers it to bone marrow macrophages that then feed iron to red cell precursors

46
Q

How is functional iron assessed?

A

By measuring haemoglobin

47
Q

How is storage iron assessed?

A

By measuring serum ferritin

48
Q

How is transported iron assessed?

A

By measuring serum iron, transferrin and transferrin saturation

49
Q

What is transferrin?

A

Protein with two bonding sites for iron

50
Q

What is the function of transferrin?

A

Transports iron from donor tissues to those expressing transferrin receptors

51
Q

What does % saturation of transferrin measure?

A

Iron supply

52
Q

What are some examples of conditions that may alter % saturation of transferrin?

A

Increased % saturation = genetic haemochromatosis

Decreased % saturation = iron deficiency, anaemia of chronic disease

53
Q

What is ferritin?

A

Large intracellular protein

54
Q

What does the tiny amount of ferritin present in serum reflect?

A

Intracellular ferritin synthesis in response to iron status

55
Q

What is serum ferritin an indirect measure of?

A

Storage iron

56
Q

What does a low ferritin indicate?

A

Iron deficiency

57
Q

What are some causes of iron deficiency?

A

Dietary insufficiency, blood loss (usually GI), malabsorption

58
Q

Is dietary iron insufficiency common in men?

A

No

59
Q

What are the types of dietary iron insufficiency?

A 
Relative = seen in children and women of child bearing age 
Absolute = seen in vegetarian diets
60
Q

What are some causes of chronic blood loss?

A

Menorrhagia, GI tumours and ulcers, NSAIDs, haematuria

61
Q

How much is the average menstrual blood loss?

A

30-40ml/month = heavy is blood loss >60ml

62
Q

Why is iron status during menstruation precarious?

A

Average daily iron intake is 1mg/day but women can lose 15-20mg/month of iron due to menstrual bleeding

63
Q

What are the sequential consequences of iron deficiency?

A

Exhaustion of iron stores
Iron deficient erythropoiesis = falling red cell MCV
Microcytic anaemia
Epithelial changes = skin, koilonychia

64
Q

How can occult blood loss cause anaemia?

A

Small volume of GI blood loss can occur without any symptoms of bleeding = this can outstrip maximum dietary iron absorption

Haematology (24 decks)

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