Anaemia Drugs - Vitamin B12 (Hydroxocobalamin)

Question 1

What is vitamin 12 more commonly known as?

1 - cobalamin
2 - acetaminophen
3 - ferrous sulphate
4 - thiamine

Answer 1

1 - cobalamin
- contained in eggs, milk and meat

Question 2

Which enzyme in the GIT is responsible for digesting vitamin B12 (cobalamin)?

1 - pancreatic lipase
2 - gastric lipase
3 - pepsin
4 - amylase

Answer 2

3 - pepsin
- active form of pepsinogen

Question 3

Once digested what does Vitamin B12 bind with in the stomach?

1 - pepsinogen
2 - carbohydrase
3 - grehlin
4 - intrinsic factor

Answer 3

4 - intrinsic factor
- secreted by parietal cells in stomach

Question 4

Once intrinsic factor has bound to B12 this becomes the B12-intrinsic factor complex. Where in the GIT is this complex recognised and absorbed?

1 - 2nd part of duodenum
2 - jejunum
3 - proximal ileum
4 - terminal ileum

Answer 4

4 - terminal ileum
- B12 is separated from intrinsic factor
- transcobalamin-II binds to B12 and this complex enters the blood

Question 5

The B12- transcobalamin-II complex is able to move around in the blood where it can go to target tissues. Some of the B12- transcobalamin-II complex can move to which organ, capable of storing it for years?

1 - kidneys
2 - muscles
3 - liver
4 - pancreas

Answer 5

3 - liver

Question 6

What is B12 involved in the synthesis of?

1 - thymidine (nucleoside used to build DNA)
2 - methionine (amino acid)
3 - coenzyme for methylmalonyl coenzyme A mutase
4 - all of the above

Answer 6

4 - all of the above

Question 7

Vitamin B12 is involved in producing pre-cursors for cell division, such as:

• thymidine (nucleoside used to build DNA)
• methionine (amino acid)
• coenzyme for methylmalonyl coenzyme A mutase

Which of the following can this then lead to?

1 - impaired cell division
2 - homocysteine
3 - methylmalonic acid
4 - macrocytic anaemia

Answer 7

4 - macrocytic anaemia
- this can then progress to megaloblastic anaemia

Question 8

Macrocytic anaemia can be caused by B12 deficiency and is due to impaired ability of bone marrow to make RBCs. The large Macrocytic RBCs are functional, but are destroyed by which organ?

1 - liver
2 - kidneys
3 - spleen
4 - pancreas

Answer 8

3 - spleen
- causes a drop in RBC number and haemoglobin

Question 9

Does B12 deficient only lead to abnormal macrocytic/megaloblastic RBCs?

Answer 9

• no
• can affect WBC and platelets

Question 10

Vitamin B12 can lead to abnormal:

• macrocytic/megaloblastic anaemia
• hypersegmented nuclei (neutrophils)
• reduced megakaryocytes

When all of 3 of the above occur due to B12 deficiency, what is this called?

1 - thrombocytopenia
2 - pancytopenia
3 - leukopenia
4 - myoleamia

Answer 10

2 - pancytopenia

Question 11

Hydroxocobalamin is the name of vitamin B12 that is given to patients. Which 2 of the following are indications for Hydroxocobalamin?

1 - microcytic anaemia
2 - macrocytic anaemia
3 - normocytic anaemia
4 - spinal cord degeneration

Answer 11

2 - macrocytic anaemia
4 - spinal cord degeneration
- B12 reduces methylmalonic acid (MA)
- MA can damage myelin sheath and affects nerve innervation

Question 12

When prescribing Hydroxocobalamin, the name of vitamin B12, we need to be careful if they have any co-exisiting B12 deficiency with what other vitamin?

1 - B1
2 - vitamin D
3 - folic acid
4 - vitamin C

Answer 12

3 - folic acid
- replacing folate alone can increase risk of damage to myelin sheath

Question 13

How is Hydroxocobalamin (vitamin B12) typically administered?

1 - oral
2 - IV
3 - IM
4 - SC

Answer 13

3 - IM
- can be given oral, but not as effective

Question 14

What is the most effective marker that can be monitored when taking vitamin B12?

1 - platelet count
2 - FBC
3 - international normalised ratio
4 - LFTs

Answer 14

2 - FBC