Anaemia and Microcytic Anaemia

Question 1

What is anaemia?

Answer 1

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

Question 2

Why are surrogate markers needed for red cell mass?

Answer 2

It is difficult to measure in routine practice

Question 3

What are some surrogate markers of red cell mass?

Answer 3

Hb concentration and haematocrit

Question 4

What method is used to measure Hb concentration?

Answer 4

The spectrophotomeric method

Question 5

What is the spectrophotomeric method for measuring Hb concentration?

Answer 5

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

Question 6

Why is optical density measured when calculating Hb concentration?

Answer 6

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

Question 7

How is Hb concentration calculated?

Answer 7

Against the known reference standard cyan-metHb concentration solution

Question 8

What is haematocrit?

Answer 8

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

Question 9

How do modern machines calculate haematocrit?

Answer 9

By adding the calculated volume of the red cells it counts

Question 10

What is the body’s response to anaemia?

Answer 10

To increase red cell production via reticulocytes

Question 11

What are reticulocytes?

Answer 11

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

Question 12

Why do reticulocytes stain purple/deeper red?

Answer 12

They still have remnants of RNA

Question 13

How do reticulocytes appear on a blood film?

Answer 13

Polychromatic

Question 14

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

Answer 14

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

Question 15

What information do automatic analysers give about red cells?

Answer 15

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

Question 16

What are the measured red cell indices?

Answer 16

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

Question 17

What are the calculated red cell indices?

Answer 17

Haematocrit, mean cell Hb, mean cell Hb concentration

Question 18

What do blood films assess?

Answer 18

Look at cellular morphology

Question 19

What does reticulocyte count assess?

Answer 19

Marrow response

Question 20

How is anaemia classified?

Answer 20

Pathophysiology or morphological characteristics

Question 21

What are the pathophysiological classifications of anaemia?

Answer 21

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

Question 22

What are some causes of decreased production of red cells?

Answer 22

Hypoproliferative = reduced amount of erythropoiesis

Maturation abnormality = erythropoiesis present but ineffective

Question 23

What are maturation abnormalities split into?

Answer 23

Cytoplasmic defects = impaired haemoglobinisation

Nuclear defects = impaired cell division

Question 24

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

Answer 24

Bleeding or haemolysis

Question 25

What is mean cell volume (MCV) useful for?

Answer 25

Distinguishing between cytoplasmic and nuclear defects

Question 26

What does a low MCV indicate?

Answer 26

Microcytic = consider problems with haemoglobinisation (cytoplasmic)

Question 27

What does a high MCV indicate?

Answer 27

Macrocytic = consider problems with maturation (nuclear)

Question 28

Where does Hb synthesis occur?

Answer 28

In the cytoplasm = defects result in small cells

Question 29

What is needed to synthesis Hb?

Answer 29

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

Question 30

How do cells with a low concentration of Hb appear?

Answer 30

Microcytic and hypochromatic

Question 31

What is the underlying pathology of hypochromatic microcytic anaemia?

Answer 31

Deficient haemoglobin synthesis as a result of a cytoplasmic defect

Question 32

What are some causes of hypochromatic microcytic anaemia?

Answer 32

Heme deficiency or globin deficiency

Question 33

What are some causes of heme deficiency?

Answer 33

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

Question 34

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

Answer 34

Iron deficiency = low body iron | Some cases of anaemia of chronic disease = normal body iron but lack of available iron

Question 35

What are some examples of problems with porphyrin synthesis?

Answer 35

Lead poisoning and pyridoxine responsive anaemias

Question 36

What is an example of a cause of globin deficiency?

Answer 36

Thalassaemia

Question 37

How does iron exist in the body?

Answer 37

As Fe2+ or Fe3+

Question 38

What is iron used for in the body?

Answer 38

Essential for oxygen and electron transport

Question 39

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

Answer 39

It is potentially toxic and can generate free radicals

Question 40

What kind of system is iron metabolism?

Answer 40

Closed system = only able to absorb small amounts of iron

Question 41

Where is iron transferred to from its storage site?

Answer 41

The marrow

Question 42

Where does iron turnover take place?

Answer 42

In the plasma pool = fast process

Question 43

What form is iron stored in?

Answer 43

Stored as ferritin = mainly found in liver

Question 44

What is circulating iron bound to?

Answer 44

Transferrin

Question 45

Where does transferrin transfer iron to?

Answer 45

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

Question 46

How is functional iron assessed?

Answer 46

By measuring haemoglobin

Question 47

How is storage iron assessed?

Answer 47

By measuring serum ferritin

Question 48

How is transported iron assessed?

Answer 48

By measuring serum iron, transferrin and transferrin saturation

Question 49

What is transferrin?

Answer 49

Protein with two bonding sites for iron

Question 50

What is the function of transferrin?

Answer 50

Transports iron from donor tissues to those expressing transferrin receptors

Question 51

What does % saturation of transferrin measure?

Answer 51

Iron supply

Question 52

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

Answer 52

Increased % saturation = genetic haemochromatosis | Decreased % saturation = iron deficiency, anaemia of chronic disease

Question 53

What is ferritin?

Answer 53

Large intracellular protein

Question 54

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

Answer 54

Intracellular ferritin synthesis in response to iron status

Question 55

What is serum ferritin an indirect measure of?

Answer 55

Storage iron

Question 56

What does a low ferritin indicate?

Answer 56

Iron deficiency

Question 57

What are some causes of iron deficiency?

Answer 57

Dietary insufficiency, blood loss (usually GI), malabsorption

Question 58

Is dietary iron insufficiency common in men?

Answer 58

No

Question 59

What are the types of dietary iron insufficiency?

Answer 59

``` Relative = seen in children and women of child bearing age Absolute = seen in vegetarian diets ```

Question 60

What are some causes of chronic blood loss?

Answer 60

Menorrhagia, GI tumours and ulcers, NSAIDs, haematuria

Question 61

How much is the average menstrual blood loss?

Answer 61

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

Question 62

Why is iron status during menstruation precarious?

Answer 62

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

Question 63

What are the sequential consequences of iron deficiency?

Answer 63

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

Question 64

How can occult blood loss cause anaemia?

Answer 64

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