Vitamins

Question 1

1) What is thiamine used in the treatment and prevention of?

2) In what 2 situations is folic acid used to treat?

Answer 1

1) Wernicke’s encephalopathy and Korsakoff’s syndrome, which are manifestations of severe thiamine deficiency.
2) Megaloblastic anaemia due to folate deficiency and in the first trimester of pregnancy to reduce the risk of neural tube defects.

Question 2

1) What is hydroxycobalamin used in the treatment of?
2) What is phytomenadione?
3) What is phytomenadione used for?

Answer 2

1) In the treatment of megaloblastic anaemia and subacute combined degeneration of the cord due to vitamin B12 deficiency.
2) The plant form of vitamin K.
3) Recommended for newborn babies to prevent vitamin K deficiency bleeding and is used to reverse the anticoagulant effect of warfarin.

Question 3

1) What vitamin is thiamine?
2) What vitamin is folic acid?
3) What vitamin is hydroxocobalamin?
4) What should be given alongside vitamin K (phytomenadione) in cases of major bleeding?

Answer 3

1) B1
2) B9
3) B12
4) Prothrombin complex concentrate

Question 4

1) What are vitamins and what are they required for?
2) In pregnancy and the preconception period, what does giving folic acid reduce the risk of?
3) What does folic acid do to prevent this?

Answer 4

1) Organic substances which are required in small amounts for normal metabolic processes.
2) Congenital neural tube defects.
3) Folic acid is required for normal cell division, and could work by facilitating cell proliferation involved in neural tube closure.

Question 5

How does phytomenadione reverse the effects of warfarin?

Answer 5

By providing a fresh supply of vitamin K for the synthesis of vitamin K-dependant clotting factors by the liver.

Question 6

1) Which 2 vitamins when given IV may rarely cause anaphylaxis?
2) In patients with co-existing B12 and folate deficiency, what should you do?
3) Why should this be done?

Answer 6

1) Phytomenadione and high dose thiamine.
2) Replace both vitamins simultaneously
3) Because replacing folic acid alone may be associated with (and hasten) progression of the neurological manifestations of B12 deficiency. The major risk is provoking subacute combined degeneration of the cord.

Question 7

1) In which patients is phytomenadione less effective in reversing warfarin?
2) What might happen when attempting to restart warfarin after vitamin K has been given?
3) How is thiamine deficiency initially best treated?

Answer 7

1) In patients with severe liver disease, because clotting factors are synthesised in the liver.
2) This may result in erratic dosing requirements.
3) With Pabrinex (vitamins B and C).

Question 8

1) How is hydroxocobalamin given?
2) What is the prescription of phytomenadione to prevent vitamin K deficiency bleeding in neonates?
3) How is an excessively high international normalised ratio caused by warfarin therapy treated?

Answer 8

1) By IM injection in vitamin B12 deficiency.
2) 1mg IM as a single dose (lower doses in preterm neonates).
3) Low dose of phytomenadione (1mg orally or IV).

Question 9

1) To prevent neural tube defects, what is the prescription of folic acid?
2) Where there is a high risk of neural tube defect, what prescription of folic acid is used?
3) When else is this dose used?

Answer 9

1) 400mcg OD started before conception or if not, at the time of pregnancy and for the first 12 weeks.
2) Where there is high risk of neural tube defect (e.g. in epilepsy), a higher dose of 5mg OD is used.
3) 5mg OD is also the dose used for folate deficiency anaemia.