haemoglobin 5: anaemia

Question 1

what is anaemia?

Answer 1

reduction in the amound of haemoglobin in a given volume of blood below what would be expected in comparison with a healthy subject of the same age and gender (by definition Hb is reduced, RBC & Hct also usually reduced)

Question 2

what are the 4 mechanisms of anaemia?

Answer 2

• reduced production of red cells / haemoglobin in bone marrow
• loss of blood from body
• reduced survival of red cells in circulation
• pooling of red cells in enlarged spleen

Question 3

what are the colours of micro/normo/macrocytic anaemic cells?

Answer 3

hypochromic/normochromic/normochromic

Question 4

what are the common mechanisms of microcytic anaemia?

Answer 4

• defect in haem synthesis (iron deficiency / chronic disease) OR
• defect in globin synthesis (thalassaemia - a-chain = a-thalassaemia, b-chain = b-thalassaemia)

Question 5

what causes macrocytic anaemia?

Answer 5

abnormal haemopoiesis - red cell precursors continue to synthesise haemoglobin and other cellular proteins but fail to divide normally

Question 6

what is a megaloblast?

Answer 6

abnormal bone marrow erythroblast that is larger than normal and shows differences in maturity between nucleus & cytoplasm

Question 7

what is megaloblastic anaemia?

Answer 7

a type of macrocytic anaemia cause specifically by a delay in the maturation of the nucleus while the cytoplams ocntinues to mature and the cell continues to grow

Question 8

what is a mechanism for macrocytic anaemia?

Answer 8

premature release of cells from bone marrow

Question 9

what are the common causes macrocytic anaemia?

Answer 9

• lack of vitamin B12 / folic acid (megaloblastic)
• drugs interfering with DNA synthesis (eg chemotherapies)
• liver disease & ethanol toxicity
• major blood loss with adequate iron stores
• haemolytic anaemia

Question 10

what are the mechanisms of normocytic anaemia?

Answer 10

• recent blood loss
• failure of red cell production
• pooling of red cells in the spleen

Question 11

what are the common causes of normocytic anaemia?

Answer 11

• peptic ulcer
• oesophageal varices
• trauma
• failure of production of red cells (early stages of iron deficiency, renal failure, bone marrow failure / suppression / infiltration eg by tumour)
• hypersplenism eg portal cirrhosis