Vitamin Deficiency

Question 1

Fat soluble:

Answer 1

A, D, E, K

Question 2

Water soluble:

Answer 2

B, C

Question 3

Vitamin A

Answer 3

• Vitamin A is mainly involved in the maintenance of healthy skin and eyes
• High levels of Vitamin A in pregnancy may cause birth defects (avoid fish oil capsules, liver and pate)
• Deficiency is rare in the UK but is associated with ocular defects (e.g. xerophthalmia) and increased susceptibility to infections.

Question 4

Vitamin B

Answer 4

• Apart from B12 deficiencies, deficiencies of B vitamins is rare in UK.
• The main role of Vitamin B1 (thiamine) is in the metabolism of carbohydrates. It is used in the treatment of alcoholic encephalopathy and deficiency.
• Vitamin B6 (pyridoxine) deficiency is rare but may occur with isoniazid therapy.
• Vitamin B2 (Riboflavin)
• Other members of B complex are nicotinamide, biotin, choline, etc.

Question 5

Thiamine (Vitamin B1):

Important safety information

Answer 5

Although potentially serious allergic adverse reactions may rarely occur during or after parenteral administration, it is recommended that:
 This should not prevent the use of parenteral thiamine
 I.V. administration should be by infusion over 30 minutes
 Facilities for treating anaphylaxis should be available.

Question 6

Pyridoxine (Vitamin B6):

Important safety information

Answer 6

 Prolonged use of pyridoxine 10mg daily is considered safe… but long-term use of pyridoxine in a dose of 200mg or more daily has been associated with neuropathy

Question 7

Vitamin C

Answer 7

• Vitamin C (ascorbic acid) therapy is essential in scurvy. Severe scurvy causes gingival swelling and bleeding which is uncommon and could indicate leukaemia.

Question 8

Vitamin D

Answer 8

• Straight-forward Vitamin D deficiency can be treated with ergocalciferol (vitamin D2) or colecalciferol (vitamin D3)  taken daily.
• Vitamin D deficiency can occur in people with limited exposure to sunlight or insufficient diet. In these individuals, ergocalciferol or colecalciferol daily by mouth may be given.
• Calcium and colecalciferol are commonly prescribed as a combination product for those with combined calcium and vitamin D deficiency or those at risk of deficiency (i.e. osteoporosis)
• If Vit. D deficiency is caused by malabsorption or chronic liver disease higher doses may be needed
• Vitamin D requires hydroxylation by the kidney to its active form. Patients with severe renal disease that require vitamin D should be given alfacalcidol or calcitriol (hydroxylated derivatives)
• Calcitriol also given in postmenopausal osteoporosis
• Common SE: Abdominal pain, headache, hypercalcaemia, hypercalciuria, nausea, skin reactions
• Symptoms of vitamin D overdose  Anorexia, lassitude, N&V, diarrhoea, constipation, weight loss, polyuria, sweating, headache, thirst, vertigo, + raised conc. of Ca2+ + phosphate in plasma and urine
• Patients receiving pharmacological doses of vitamin D should have their plasma-calcium conc. checked at intervals (initially once or twice weekly) + whenever nausea or vomiting occur.

Question 9

Vitamin K

Answer 9

• Vitamin K (phytomenadione) is essential for the production of clotting factors.
• It is a fat-soluble vitamin so patients with fat malabsorption (especially in biliary obstruction) or liver problems may become deficient.
• Interacts with warfarin (antagonising effect)

Question 10

Vitamin E

Answer 10

• Tocopherol (powerful antioxidant)

- Prevents platelet aggregation hence interacts with warfarin (increased risk of bleeding)

Question 11

Neural tube defects (prevention in pregnancy)

Answer 11

Neural tube defects represent a group of congenital defects, caused by incomplete closure of the neural tube within 28 days of conception. Most common forms are anencephaly, spina bifida and encephalocele.

The main risk factors are maternal folate deficiency, maternal vitamin B12 deficiency, previous history of having an infant with a neural tube defect, smoking, diabetes, obesity, and use of antiepileptic drugs.

Folic acid supplements are taken before + during pregnancy (up to week 12) to reduce the risk of neural tube defects.

• Women at low risk should receive 400mcg before conception and until week 12 of pregnancy.
• Women at high risk (e.g. malabsorption, diabetes, sickle-cell disease, antiepileptic drugs, had previous infant with neural tube defects) should take 5mg until week 12 of pregnancy.