Red Cell Disorders

Question 1

Describe the size of RBCs in iron deficiency anaemia, renal anaemia, pregnancy, megaloblastic anaemia, and thalassaemia.

Answer 1

. Iron deficient anaemia- microcytic
. Renal- normocytic
. Pregnancy- normocytic
. Megaloblastic- macrocytic
. Thalassaemia- microcytic

Question 2

How does aplastic anaemia arise?

Answer 2

Bone marrow failure

Question 3

What is Polythaemia? Give an example of when this can occur.

Answer 3

. Polythaemia is having too many RBCs, which makes the blood viscous so it flows poorly
. People with COPD get hypoxic, so the kidneys release EPO to produce more RBCs to compensate for this hypoxia, which can lead to polythaemia

Question 4

What is renal anaemia and how is it treated?

Answer 4

. EPO levels low (therefore not many RBCs produced)

. Treated with iron and EPO

Question 5

What is megaloblastic anaemia? How can this be treated?

Answer 5

. Deficiency in vitamin B12 or folate (cofactor in DNA synthesis) leads to defective DNA synthesis, which causes macrocytic RBCs
. Give methotrexate followed by folic acid

Question 6

What is pernicious anaemia?

Answer 6

. Subset of megaloblastic anaemia caused by being unable to absorb B12 due to autoimmune disease

Question 7

What is haemolytic anaemia?

Answer 7

Increased destruction of RBCs

Question 8

What is the cause of sickle cell anaemia? What does this result in?

Answer 8

. Caused by SNP which leads to an AA substitution
. AA sub causes production of abnormal Hb
. Abnormal Hb forms crystals at low oxygen so that RBCs form sickle shapes that may block microcirculation
. Can result in haemolytic anaemia

Question 9

What is thalassaemia caused by and what does this result in?

Answer 9

. Genetic disorder causes slower rate of production of alpha and beta subunits of haemoglobin
. Reduces RBC volume and haematocrit

Question 10

What are colony-stimulating factors? What condition are they sometimes used to treat?

Answer 10

. Stimulate production of WBCs

. Used to treat aplastic anaemia, where failure of bone marrow causes pancytopenia (reduced RBCs, WBCs, platelets)

Question 11

What type of anaemia arises when you don’t intake enough vitamin B12?

Answer 11

Megaloblastic anaemia (vit B12 needed as cofactor for normal DNA synthesis. Lack of B12 leads to abnormal DNA synthesis which produces macrocytic RBCs)