Vitamin B12 deficiency

Question 1

Vitamin B12 (cobalamin) is a water-soluble vitamin that is naturally found in animal and dairy products, but the human body is unable to synthesise this alone. What is the incidence of vitamin B12 deficiency?

1 - 1000 cases per 100,000
2 - 100 cases per 100,000
3 - 10 cases per 100,000
4 - 1 cases per 100,000

Answer 1

3 - 10 cases per 100,000

Equally common in men or women

Question 2

Vitamin B12 (cobalamin) is a water-soluble vitamin that is naturally found in animal and dairy products, but the human body is unable to synthesise this alone. What age does the incidence of this peak?

1 - 20-30
2 - 30-40
3 - 40-50
4 - 50-60

Answer 2

4 - 50-60

Question 3

All of the following are common causes of vitamin B12 deficiency, but which is by far the most common?

1 - Malabsorption (most common)
2 - Inadequate intake
3 - Increase in requirement
4 - Drug induced
5 - Congenital

Answer 3

1 - Malabsorption (most common)

Includes:
- Chronic alcoholism
- Pernicious anaemia
- Helicobacter pylori infection
- Atrophic gastritis (mainly due to pernicious anaemia and Helicobacter pylori infection)
- Bowel related conditions, e.g. Crohn’s disease, Coeliac disease, tropical sprue
- Surgery: gastrectomy, gastric bypass, terminal ileum resection
- Bacterial overgrowth

Question 4

Which of the following is NOT a process where a patient has a greater B12 requirement which could ultimately lead to B12 deficiency?

1 - Pregnancy
2 - Vegan diet
3 - Breastfeeding
4 - Hyperthyroidism
5 - Acquired immunodeficiency syndrome (AIDS)
6 - α-thalassaemia

Answer 4

2 - Vegan diet
This causes B12 deficiency due to low intake

Question 5

B12 is digested by pepsinogen and then bound to intrinsic factor in the stomach, allowing it to pass through the small intestines. Which cell of the stomach produces intrinsic factor?

1 - goblet cells
2 - parietal cells
3 - chief cells
4 - D cells

Answer 5

2 - parietal cells

Any disease of stomach, or following surgery can therefore affect the level of intrinsic factor

Question 6

Where is the GIT is B12 absorbed?

1 - stomach
2 - 1st part of the ileum
3 - 3rd part of duodenum
4 - terminal ileum

Answer 6

4 - terminal ileum

Any disease of ileum, or following surgery can therefore affect the level of intrinsic factor

Question 7

Once absorbed, B12 (cobalamin) 50% enters the circulation and the other 50% travels where for storage?

1 - kidney
2 - bones
3 - liver
4 - spleen

Answer 7

3 - liver

Can be stored for 4 years. Therefore deficiency is typically due to long term low B12 levels

Question 8

What is the cut off for B12 deficiency?

1 - <148 mg/L
2 - <148 picomole/L
3 - 248 picomole/L
4 - 548 mcg/L

Answer 8

2 - <148 picomole/L

NICE suggests that a level of less than 200 nanograms/L (148 picomole/L) has a high sensitivity in diagnosing 97% patient

Deficiency is likely: <148 picomole/L
Deficiency is probable: 148 to 258 picomole/L
Deficiency is unlikely: >258 picomole/L

Question 9

All of the following are causes of B12 (cobalamin) deficiency, but which is the most common cause in the UK?

1 - Helicobacter pylori
2 - Atrophic gastritis
3 - Pernicious anaemia
4 - Vegan diet

Answer 9

3 - Pernicious anaemia
Form of malabsorption classification

Should always suspect if patient has other autoimmune conditions, and test for anti-intrinsic antibodies

Question 10

Which 2 of the following drugs have been shown to cause B12 deficiency?

1 - omeprazole
2 - bisoprolol
3 - ramipril
4 - metformin
5 - atorvastatin

Answer 10

1 - omeprazole
4 - metformin

Question 11

Patients with B12 (cobalamin) deficiency may present with which if the following basic symptoms?

1 - general illness
2 - fatigue and weakness
3 - pallor (due to anaemia)
4 - light headedness
5 - all of the above

Answer 11

5 - all of the above

Question 12

Which of the following does B12 (cobalamin) deficiency cause in relation to anaemia?

1 - microcytic anaemia <80fL
2 - normocytic anaemia 80-100fL
3 - macrocytic anaemia >100fL

Answer 12

3 - macrocytic anaemia >100fL

Specifically it causes Megaloblastic, where RBCs are not made correctly and are much larger than normal

Question 13

B12 (cobalamin) can cause all of the following neurological effects, EXCEPT which one?

1 - Subacute Combined Degeneration of Spinal Cord (demyelination)
2 - Polyneuropathy (hands and feet normally)
3 - Cognitive Impairment (memory loss, mood changes, depression, psychosis or dementia-like syndrome may be observed)
4 - Retinopathy (complete loss of vision)

Answer 13

4 - Retinopathy (complete loss of vision)

Question 14

Which 2 of the following symptoms does B12 (cobalamin) deficiency?

1 - glossitis
2 - oral ulcers
3 - enlarged parotid gland
4 - dupuytren’s contracture
5 - angular cheilitis

Answer 14

1 - glossitis
5 - angular cheilitis

Epithelial cells of tongue are continually being turned over and require B12. Without this the tongue can become inflamed.

Question 15

Does B12 (cobalamin) deficiency only affect RBCs?

Answer 15

• No

Typically RBCs are affected 1st, but can cause pancytopenia (RBC, WBC and Platelets)

Question 16

What is typically the 1st line test used to diagnose patients with B12 (cobalamin) deficiency?

1 - FBC
2 - anti-intrinsic factor
3 - gastroscopy
4 - endoscopy

Answer 16

1 - FBC

Give all of the following to help diagnose the patient:

• haemoglobin level
• mean cell volume (MCV)
• reticulocyte

Question 17

All of the following are common findings in patients with B12 (cobalamin) deficiency, EXCEPT which one?

1 - Haematocrit: low
2 - MCV: high >100fL
3 - Reticulocyte: high
4 - Lactate dehydrogenase (LDH): high

Answer 17

3 - Reticulocyte: high

This will be low as there is a lack of B12 to be able to make enough new RBCs

Question 18

In pregnancy, or patients taking oral contraception, would we expect to see normal, low, or increased levels of B12 (cobalamin)?

Answer 18

• Typically will be low

Oral contraception reduces vitamin B12 carrier protein and thus B12

Pregnancy increases B12 demand, and can therefore be low

Question 19

All of the following are likely differentials for B12 (cobalamin) deficiency, EXCEPT which one?

1 - liver cirrhosis
2 - iron deficiency anaemia
3 - folate deficiency
4 - myelodysplastic Syndrome (MDS)

Answer 19

1 - liver cirrhosis

Question 20

Are patients with B12 (cobalamin) deficiency typically treated in primary or secondary care?

Answer 20

• primary care

Given as hydroxocobalamin via intramuscular (IM) vitamin B12 injections as replacement and maintenance therapy

Question 21

Hydroxocobalamin is given to patients with B12 (cobalamin) deficiency. What is the replacement dose in patients without neurological symptoms?

1 - 1mg every day for 2 weeks
2 - 10mg once per week
3 - 1mg 3 times/week for 2 weeks
4 - 1mg twice per year

Answer 21

3 - 1mg 3 times/week for 2 weeks

1mg once daily on alternative days until no further improvement in patients with neurological symptoms

Question 22

Hydroxocobalamin is given to patients with B12 (cobalamin) deficiency. What is the maintenance dose in diet related patients without neurological symptoms?

1 - 1mg every day for 2 weeks
2 - 10mg once per week
3 - 1mg 3 times/week for 2 weeks
4 - 1mg twice per year

Answer 22

4 - 1mg twice per year

In non-diet related B12 (cobalamin) deficiency = 1mg once every 2-3 months for life

1mg once every 2 months for life in patients who have presented with neurological symptoms

Question 23

Once starting Hydroxocobalamin for patients with B12 (cobalamin) deficiency, how soon should they have their FBC checked to assess for treatment response?

1 - 24h
2 - 24-72h
3 - 7-10 days
4 - 14-21 days

Answer 23

3 - 7-10 days

Serum iron and folate level should be checked 8 weeks after treatment; MCV should be within the normal range.

Question 24

If a patient has B12 and folate deficiency together, which of them should be given 1st?

Answer 24

• B12

It is essential to treat the B12 deficiency first before correcting the folate deficiency. Giving patients folic acid when they have a B12 deficiency can lead to subacute combined degeneration of the cord, with demyelination in the spinal cord and severe neurological problems.