Anaemia

Question 1

Define anaemia

Answer 1

Reduction in the amount of haemoglobin in a given volume of blood below what would expected in comparison to a healthy subject of the same age and gender (HB reduced)

The RBC and Hct are usually reduced, usually relates to an increase in plasma but not an increase in Hb

Question 2

Describe the mechanisms of anaemia and classification

Answer 2

1. Reduced production of red cells/ haemoglobin in the bone marrow
2. Loss of blood from the body
3. Reduced survival of red cell in the circulation
4. Pooling of red cells in spleen

The classification is based on cell size; microcytic is hypochromia and normocity is monochromic, macrocytic is normochromic

Question 3

What are the causes of microcytic anaemia

Answer 3

1. Defect in haem synthesis: due to iron deficiency because Fe is trapped in macrophages, or anaemia of chronic disease eg rheumatoid anaemia and inflammation.
2. Defect in globin synthesis (thalassaemia) defects in alpha/ beta synthesis

Question 4

Describe how macrocytic anaemia arises and its common causes

Answer 4

Abnormal haemopoiesis so red cell precursors continue to synthesise haemoglobin and other cellular proteins but they fail to divide normally. As a result the red cells are much larger than normal.

Megaloblastic erythropoiesis may cause this due to delay in maturation

Causes:

1. Lack of vitamin B12 or follic acid
2. Use of drugs interfering with DNA synthesis eg cancer treatment in leaukamia
3. Liver disease and ethanol toxicity
4. Recent majors blood loss with adequate iron stres (reticulocytes increased)
5. Haemolytic anaemia (reticulocyte anaemia)

Question 5

Describe the basis and causes of normocytic and chromic anaemia

Answer 5

Basis: MCV and MCH are normal, recent blood loss and failure of red cell production, pooling of red cells in spleen.

Causes:

1. Peptic ulcers (other trauma - blood loss)
2. Failure of production of red cells
3. Hypersplenism

Question 6

Describe haemolytic anaemia

Answer 6

Anaemia resulting from shortened survival of red cells in the circulation so the RBCs are metabolised in <120 days (bone marrow can’t keep up).
Can be suspected when unexplained anaemia and look at table
Classification:

1. Inherited - abnormalities in cell membrane and in Hb enzyme.
2. Acquired- from extrinsic factors such as microorganisms or chemicals.

Question 7

Explain hereditary spherocytosis

Answer 7

Haemolytic anaemia or chronic haemolytic resulted from an inherited intrinsic defect of the red cell. After entering the circulation = cell lose membrane = sphere.

Red cells become less flexible and are removed prematurely by the spleen (extravascular haemolysis). The bone marrow responds to haemolysis by an increased output of red cell leading to polychromasia and eticulocytes. Increased bilirubin production, jaundice, gall stone

Question 8

Describe the effect of G6PD

Answer 8

Important enzyme in the phosphate pentose shuttle. It is essential for the production of the red cell from oxidant damage. Oxidants may be generated in blood stream. Look at notes

Question 9

Describe autoimmune haemolytic anaemia

Answer 9

Look at notes?