Anaemia Intro and Microcytic Anaemia

Question 1

What is the definition of anaemia and how is it measured?

Answer 1

decreased red cell mass

- measured by Hb levels or haematocrit (Hct) levels

Question 2

What is a normal Hb in male and female adults?

Answer 2

M - 130g/L
F - 120g/L

less than this indicates anaemia

Question 3

Describe how red cell production appears on a sample of bone marrow?

Answer 3

Several erythroid precursors cluster around a central “nursing” macrophage (histiocyte)

Question 4

How is haemoglobin concentration measured using a spectrophotometric method?

Answer 4

• Burst red cells => create Hb solution
• Stabilise Hb molecules (cyan-metHb)‏
• Measure optical density
• OD Proportional to the concentration (Beer’s Law)
• compared to reference curve for Hb conc.

Question 5

How is haematocrit measured/expressed?

Answer 5

• Expressed as a ratio of red cells in whole blood
• previously analysed by spinning red cells out of plasma in centrifuge and working out % of red cells
• Nowadays modern machines add the calculated volume to the number of red cells it counts

Question 6

When are Hb and Hct concentrations NOT a good marker of total RBCs?

Answer 6

If pt is losing blood quickly
- Hb and Hct can look normal if plasma volume is smaller

If patient has been haemodiluted
i.e. given fluids and plasma volume expands
=> relative low Hb/Hct

Question 7

What is a typical response to anaemia that can be seen on blood film?

Answer 7

reticulocytosis

Question 8

How can reticulocytes be identified on a blood film?

Answer 8

• contain residual RNA => more purple in colour
  => Blood film appears ‘polychromatic’
• slightly larger than other RBCs
• no central pallor

Question 9

What can automated analysers tell us about RBCs?

Answer 9

Hb concentration
number of RBCs (concentration)
size of RBCs (MCV)

Question 10

How can anaemia be classified by the pathophysiology?

Answer 10

Decreased production
=> (low reticulocyte count)‏

Increased loss or destruction of red cells
=> (high reticulocyte count)‏

Question 11

What can cause a decreased production of RBCs leading to anaemia?

Answer 11

Hypoproliferative – reduced erythropoiesis

Maturation abnormality – erythropoiesis present but ineffective

• problem in cytoplasm (impaired Hb)
• problems in nucleus (Impaired cell division)

Question 12

What can cause an increased loss/destruction of RBCs?

Answer 12

• Bleeding

- Haemolysis

Question 13

What does the MCV (size of cells) tell you about the reason for the anaemia?

Answer 13

If MCV low (microcytic) consider problems with haemoglobinisation
=> e.g. not enough iron to make haem group for Hb

If MCV high (macrocytic) consider problems with nuclear maturation
=> nucleus is not mature enough to cell divide properly, so mature red cells end up bigger than normal

Question 14

What constituents are needed to make Hb, and what can occur if there is not enough of these constituents?

Answer 14

Globins
Haem
Porphyrin ring
Iron (Fe 2+)‏

Shortage results in:

• small red cells (microcytic)
• low hb content
• hypochromic (lacking in colour)‏

Question 15

What can cause there to be a shortage in any of the constituents needed to make Hb? I.e. what can cause microcytic anaemias?

Answer 15

• Iron deficiency (low body iron)‏
• Thalassaemia (Globin deficiency)
• Problems with porphyrin synthesis (RARE)
  e. g. Lead poisoning

Question 16

HOw can the blood volume be estimated by the haemoglobin level?

Answer 16

If Hb 2500mg then double this for blood in ml
=> 5000ml
=> around 5 litres blood

Question 17

Where is most iron kept in the body?

Answer 17

in the haemoglobin

- only some is stored as ferritin mainly in liver

Question 18

HOw is circulating iron transported around the body?

Answer 18

Circulating iron is bound to transferrin

Question 19

HOw can we test a patients iron status?

Answer 19

Functional iron
- Check Haemoglobin**

Transported iron

• Serum iron
• Transferrin
• Transferrin saturation

Storage iron
- Check Serum ferritin**

Question 20

What does measuring the transferrin saturation tell us?

Answer 20

measures iron supply

• reduced in iron deficiency
• reduced in anaemia of chronic disease
• increased in genetic haemachromatosis

Question 21

HOw can iron deficiency be confirmed?

Answer 21

Combination of:

• anaemia (decreased functional iron)
• reduced storage iron (low serum ferritin)

Question 22

WHat are the potential causes of iron deficiency?

Answer 22

Lack of dietary iron
RELATIVE 
- pregnant
- children needing to grow
ABSOLUTE 
- vegetarian diets

Blood loss (GI)

Malabsorption

• Coeliac disease
• achlorhydria‏ (lack of acid to digest iron - e.g. due to PPI)

Question 23

What types of chronic blood loss may cause an iron deficiency anaemia?

Answer 23

Menorrhagia

GI

• Tumours
• Ulcers
• NSAIDs

Haematuria

Question 24

What are the potential consequences of an abnormally low iron?

Answer 24

Use up iron stores
Erythropoiesis with no iron
RBC MCV decreases => Microcytic Anaemia

=> Epithelial changes of skin and koilonychia of nails

Question 25

What must you also do whilst treating symptoms of an iron deficiency anaemia?

Answer 25

Investigate for a cause

=> Early tx may be curative (e.g. GI tumours)