Anaemia

Question 1

What is anaemia?

Answer 1

Anaemia is a reduction in the haemoglobin concentration (Hb) in the circulating blood below what is normal for a healthy person of the same age and gender as the individual.

Question 2

What is anaemia usually associated with?

Answer 2

Anaemia is usually associated with a reduction in the red blood cell count (RBC) and the haematocrit (Hct) (previously referred to as packed cell volume (PCV)).

Question 3

What are the four main mechanisms that result in anaemia?

Answer 3

Reduced production of red cells by the bone marrow e.g. iron/B12/folate deficiency.

Loss of blood from the body e.g. gastrointestinal bleeding, heavy menstrual bleeding.

Reduced survival of red cells in the circulation (haemolysis) e.g. sickle cell disease, G6PD deficiency, hereditary spherocytosis.

Increased pooling of red cells in an enlarged spleen e.g. splenic sequestration in a young child with sickle cell anaemia.

Question 4

Anaemia can not only be described by the mechanism that caused it but also by what?

Answer 4

The size of the red cells.

Question 5

What are the three cell sizes?

Answer 5

Microcytic (small)
Normocytic (normal)
Macrocytic (large)

Question 6

In what sort of anaemias is the size of the cell not as important as the mechanism?

Answer 6

In macrocytic and normochromic normocytic anaemias

Question 7

What is the reticulocyte count? How do we carry this out? What will we see?

Answer 7

The reticulocyte count is the amount of young red cells. It involves exposing living red cells to a dye (new methylene blue) that is stains the higher RNA content of young red blood cells so that they can be counted.

Question 8

How else could we tell if there were lots of reticulocytes (without using methylene blue)?

Answer 8

We would see cells with polychromasia.

Question 9

What causes polychromasia?

Answer 9

Polychromasia means that cells have a blue tinge, caused by the ribosomal RNA in young red cells, in addition to the pink colour of the haemoglobin – hence ‘polychromasia’ - ‘many colours’.

Question 10

When do we see an increased reticulocyte count?

Answer 10

An increased reticulocyte count is seen as a response to haemolytic anaemia and recent blood loss and also as a response to treatment with iron, vitamin B12 or folic acid.

Question 11

When do we see an decreased reticulocyte count?

Answer 11

A reduced reticulocyte count is seen when there is a reduced output of red cells from the bone marrow.

Question 12

What are some other features microcytic cells (microcytes) are associated with?

Answer 12

Microcytic cells are usually also hypochromic.

Question 13

What are some common causes of microcytosis?

Answer 13

Iron deficiency anaemia
Anaemia of chronic disease
Thalassaemia

Question 14

What causes microcytosis?

Answer 14

Microcytosis results from the reduced synthesis of haemoglobin.
This can be caused by reduced synthesis of haem (iron deficiency or anaemia of chronic disease) or reduced synthesis of globin (thalassaemia).

Question 15

When may a patient lose a lot of blood without realising/noticing much?

Answer 15

Gastrointestinal bleeds (especially this).
Heavy menstrual bleeding may also be overlooked as just a particularly heavy period.
Hookworm.

Question 16

What are the three main reasons for iron deficiency?

Answer 16

Blood loss
Insufficient intake
Increased requirements

Question 17

What are the three main stages of iron deficiency?

Answer 17

Iron depletion, iron deficiency and iron deficiency anaemia.

Question 18

What can we observe in iron depletion?

Answer 18

Storage iron reduced or absent.

Question 19

What can we observe in iron deficiency?

Answer 19

Low serum iron and transferrin saturation.

Question 20

What can we observe in iron deficiency anaemia?

Answer 20

Low haemoglobin and haematocrit levels.

Question 21

What are some symptoms of iron deficiency anaemia?

Answer 21

Pallor, fatigue, breathlessness.

Failure to thrive or impaired intellectual development in children.

Question 22

What is ACD?

Answer 22

Anaemia of Chronic Disease - anaemia in patients who are unwell; there is usually an inflammatory aspect to the underlying disease.

Question 23

What are some common causes of ACD?

Answer 23

Rheumatoid arthritis 
Autoimmune disease 
Malignancy 
Kidney disease 
Infections such as TB or HIV

Question 24

Why may chronic infections cause anaemia?

Answer 24

Cytokines such as TNF alpha and interleukins in chronic disease lead to a decrease in erythropoietin production and also prevent the normal flow of iron from the duodenum to the red blood cells.

Question 25

How can we tell the difference between anaemia of chronic disease and iron deficiency?

Answer 25

Some laboratory clues of chronic disease that aren’t present in iron deficiency include:
C-reactive protein is high

Erythrocyte sedimentation rate (ESR) is high

Question 26

How else may we diagnose anaemia of chronic disease?

Answer 26

High ferritin levels
Low transferrin levels
Acute phase proteins increase.

Question 27

Why is distinguishing between anaemia of chronic disease and iron deficiency important?

Answer 27

As patients with anaemia of chronic disease have plenty of storage iron, treating with iron replacement therapy (as you would for patients with iron deficiency anaemia) will not help and should be avoided.

Question 28

How would we treat ACD?

Answer 28

Controlling the underlying disease to reduce inflammation (e.g. by treating the infection) will treat the anaemia, however this is not always possible and some of these patients benefit from erythropoietin treatment.

Question 29

In normocytic anaemia, what other feature is present in the blood cells?

Answer 29

Normal colour (normochromic)

Question 30

What are the three main mechanisms for normocytic anaemia?

Answer 30

Blood loss.
Failure of production of red cells.
Pooling of red cells in the spleen.

Question 31

What may cause red cells to pool in the spleen?

Answer 31

Hypersplenism, e.g. liver cirrhosis.

Splenic sequestration in sickle cell anaemia.

Question 32

In macrocytic anaemia, the red cells are large. How do we assess the size of blood cells?

Answer 32

Examining a blood film or by noting an elevated MCV.

Question 33

What causes the red cells to become macrocytic?

Answer 33

Abnormal haemopoiesis leading to red cell precursors continuing to synthesise haemoglobin and other cellular proteins but failing to divide normally.

Question 34

One cause of macrocytic anaemia is megaloblastic erythropoiesis. What does the refer to?

Answer 34

This refers specifically to a delay in maturation of the nucleus while the cytoplasm continues to mature and the cell continues to grow.

Question 35

Where do we see megaloblasts? Where do we tend not to find them?

Answer 35

We generally see them in the bone marrow, not in the blood film.

Question 36

What are some causes macrocytic anaemia?

Answer 36

Lack of vitamin B12 and/or folic acid.
Use of drugs that interfere with DNA synthesis.
Liver disease and ethanol toxicity.
Recent major blood loss with adequate iron stores.
Haemolytic anaemia (reticulocytes increased).

Question 37

Why would an increased reticulocyte count suggest macrocytic anaemia?

Answer 37

Reticulocytes are about 20% larger than mature red cells, so increased reticulocyte concentration would increase the mean cell volume.

Question 38

What is a megaloblast?

Answer 38

An abnormal bone marrow erythroblast.

Question 39

What does a megaloblast look like?

Answer 39

It is larger than normal and shows nucleocytoplasmic dissociation. It may also have Howell-Jolly bodies.

Question 40

What is megaloblastic anaemia caused by?

Answer 40

Vitamin B12/folate deficiency.

Question 41

How do we diagnose megaloblastic anaemia?

Answer 41

We can suspect it from the blood features but to be sure requires bone marrow examination.

Question 42

What would we see on a megaloblastic blood film?

Answer 42

Tear drop cells.
Hypersegmented nuclei in neutrophil.
Oval macrocytes.