Erythropoiesis and anaemia

Question 1

What is erythropoiesis?

Answer 1

• Red blood cells cannot divide to replenish their numbers. Thus, they are replaced by new cells
• Erythropoiesis is the process which produces red blood cells

Question 2

What triggers red blood cell formation?

Answer 2

• Erythropoiesis is triggered by a decrease in O2 circulation which is detected by kidneys
• The kidneys then secrete a hormone called erythropoietin
• This hormone stimulates proliferation and differentiation of red cell precursors

Question 3

What is haematopoiesis? List the stages of haematopoises involved in RBC formation.

Answer 3

• Haematopoiesis is the name given to the differentiation process

The stages are as follows:
• Blood stem cells
• Myeloid stem cells
• RBC

Question 4

Describe the stages of erythropoeisis

Answer 4

• Hemocytoblast: starts as a stem cell
• Proerythroblast: nucleus, no haemoglobin
• Basophilic erythroblast: nucleus condensing, Hb formation, lots of ribosomes
• Polychromatophilic erythroblast: cells getting smaller, losing organelles, nucleus shrinking, producing Hb
• Normoblast: 35% Hb
• Reticulocyte: no nucleus, reduce size, still contain some RNA. Thus it cannot replicate/ duplicate itself
• Mature RBC: no DNA, no RNA, thus no genetic material which means it cannot synthesize Hb

Question 5

How is the process of erythropoiesis regulated?

Answer 5

• Low O2 levels, low Hb levels activates production
• Erythropoietin is produced in the kidney and liver in response to low oxygen levels
• In addition, erythropoietin is bound by circulating red blood cells
• So, if there are low circulating numbers of RBC, there is a high level of unbound erythropoietin = stimulates production in the bone marrow
• Spleen: acts as a sieve. Newer RBC have more flexibility thus they can pass through. Older ones are more rigid, thus they cannot pass through the organ = destroyed
• Macrophages in liver takes the iron, and transports them to receptors in the bone marrow, recycling them

Question 6

What are the types of anaemia?

Answer 6

Iron absorption and iron deficiency anaemia

Microcytic anaemia

Macrocytic anaemia

Normocytic anaemia

Question 7

What is the cause of Iron absorption and iron deficiency anaemia?

Answer 7

Causes: 
• Increased iron requirements (foetus steals iron from mother)
• Growth demands 
• Limited external supply: Poor intake 
• Malabsorption
• Bleeding 
• Venesection

Question 8

What is the cause of microcytic anaemia?

Answer 8

Microcytic cells look smaller than normal
• Iron deficiency anaemia
• Thalassaemia (genetic disorder, abnormal Hb

Question 9

What is the cause of macrocytic anaemia?

Answer 9

Looks bigger than normal
• Vitamin B12 or folate deficiency which impairs DNA synthesis
• Insufficient intake of vitamins
Deficient absorption:
• Gastrectomy
• Autoimmune attack – antibodies may attack the factors that help absorb the vitamins e.g. pernicious anaemia

Question 10

What is the cause of normocytic anaemia?

Answer 10

• Decreased production: Anaemia of chronic disease (common)
• Increased destruction or loss: Acute bleeding, hypersplenism (overactive spleen which roves RBC too early and too quickly), haemolytic disorders
• Increased plasma volume: pregnancy

Question 11

List the possible causes of anaemia

Answer 11

• Deficient production of red blood cells
• Excessive destruction of red blood cells
• Blood loss or haemorrhaging

Question 12

Describe the clinical features of anaemia

Answer 12

Symptoms: subjective 
• Tiredness 
• Dizziness 
• Palpitation 
• Headache 

Signs: objective
• Pallor: conjunctivae, skin, oral mucosa
• Jaundice
• Koilonychia (spoon nails)

Question 13

Describe the oral manifestations of anaemia

Answer 13

Oral manifestations
• Pallor

Atrophic glossitis
• smooth glossy appearance with red or pink background tongue
• E.g., pernicious anaemia

Angular cheilitis
• Inflamed and cracked skin at the angles of the mouth
• E.g., iron deficiency anaemia