megaloblastic anaemia

Question 1

what do most megaloblastic anaemias result from? (2)

Answer 1

either lack of B12 or folate

Question 1

Most megaloblastic anaemias result from lack of either B12 or folate. Need to establish which deficiency is present in each case and the underlying cause. But what would you do in emergencies?

Answer 1

Delay could be dangerous
Sometimes necessary to administer both B12 and folate after bone marrow test whilst waiting for plasma assay results

Question 2

This is one cause of megaloblastic anaemia in the UK, in which lack of gastric intrinsic factor resulting from an autoimmune gastritis causes malabsorption of vit B12

Answer 2

pernicious anaemia

Question 3

One cause of megaloblastic anaemia in the UK is pernicious anaemia - how does this occur?

Answer 3

lack of gastric intrinsic factor resulting from an autoimmune gastritis causes malabsorption of vitamin B12.

Question 4

in pernicious anaemia does the pt have B12 or folate deficiency

Answer 4

B12

Question 5

what is needed in the treatment of the rare syndrome of congenital transcobalamin II deficiency? folate or B12?

Answer 5

B12

Question 6

What is needed in the treatment of megaloblastosis caused by prolonged nitrous oxide anaesthesia?

Answer 6

B12
It inactivates the vitamin

Question 7

What effect can prolonged nitrous oxide treatment anaesthesia have?

Answer 7

It inactivates vitamin b12
thus B12 will be needed in the treatment of megaloblastosis caused by prolonged NO anaesthesia

Question 8

What needs to be given prophylactically after total astrectomy or total ileal resection

Answer 8

B12

Question 9

True or false. Vitamin B12 should be given after partial gastrectomy.

Answer 9

False
Only give if vit B12 absorption test shows malabsorption.
It should be given prophylactically for TOTAL gastrectomy or total ileal resection

Question 10

Apart from diet deficiency, all other caused of B12 deficiency are due to ..

Answer 10

malabsorption

Question 11

Discuss the use of oral vit B12 - low dose, instrinsic factor complexes, large doses

Answer 11

There is little place for the use of low-dose vitamin B12 orally and none for vitamin B12 intrinsic factor complexes given by mouth. Vitamin B12 in larger oral doses may be effective.

Question 12

T or F - hydroxycobalamin retained in body longer than cyanocobalamin

Answer 12

True

Question 13

Hydroxocobalamin is retained in the body longer than cyanocobalamin and thus for maintenance therapy can be given at intervals of up to how many months?

Answer 13

3 months

Question 14

What does vit B12 treatment usually consist of

Answer 14

Treatment is generally initiated with frequent administration of intramuscular injections to replenish the depleted body stores. (hydoxycobalamin)
Thereafter, maintenance treatment, which is usually for life, can be instituted.

Question 15

True or false - maintenance treatment of vit B12 is usually for life

Answer 15

true

Question 16

Do larger doses than those recommended provide additional benefit in vit B12 neuropathy?

Answer 16

There is no evidence that doses larger than those recommended provide any additional benefit in vitamin B12 neuropathy.

Question 17

Discuss the use of folic acid as long term therapy

Answer 17

Folic acid has few indications for long-term therapy since most causes of folate deficiency are self-limiting or will yield to a short course of treatment.

Question 18

Can you use folic acid in undiagnosed megaloblastic anaemia?

Answer 18

No, unless vitamin B12 is administered concurrently otherwise neuropathy may be precipitated.

Question 19

In folate-deficient megaloblastic anaemia (e.g. because of poor nutrition, pregnancy, or antiepileptic drugs), how would you treat it & for how long?

Answer 19

daily folic acid supplementation for 4 months brings about haematological remission and replenishes body stores.

Question 20

Drug therapy of folic acid for prophylaxis in chronic haemolytic states, malabsorption, or in renal dialysis

Answer 20

folic acid is given daily or sometimes weekly, depending on the diet and the rate of haemolysis.

Question 21

What is folinic acid used for (anaemia indication)?
What is it given as?
Is it given alongside anything?

Answer 21

effective in the treatment of folate deficient megaloblastic anaemia but it is generally used in association with cytotoxic drugs; it is given as calcium folinate.

Question 22

Folic acid doses for
- prevention neural tube defects in pt at low risk of concieving child with neural tube defects
- prevention neural tube defects in pt at high risk of conceiving child with neural tube defects
- prevention of nueral tube defects in pt with sickle cell disease

Answer 22

1. 400mcg daily before conception and till week 12 of pregnancy
2. 5mg daily before conception and until week 12 pregnancy
3. 5mg daily before pregnancy and continued throughout pregnancy

Question 23

Why should folic acid never be given alone for pernicious anaemia or other megaloblastic anameias caused by B12 deficiency

Answer 23

it can mask B12 deficiency which can result in serious irreversible nerve damage e.g. may precipitate subacute combined degeneration of spinal cord and neuraphy

Question 24

Cyanocobalamin dose should be taken…

Answer 24

between meals

Question 25

Treatment of B12 deficiency with no neurological involvement

Answer 25

IM hydroxycobalamin 3x week for 2 weeks
Maintenance
- IM hydroxy every 3 months for life (where B12 deficiency is not diet related)
- oral cyanocobalamin tabs or twice yearly IM hydroxy (where it is thought to be diet related)

Question 26

What are vegans at risk of

Answer 26

B12 deficiency if they do not take fortified foods or supplements