Vitamin A deficiency

Question 1

What is the active form of vitamin A?

Answer 1

Retinoic Acid

Question 2

Give 5 sources of vitamin A

Answer 2

Liver
Kidneys
Butter
Egg yolks
Leafy vegs

Question 3

What does vitamin A deficiency cause?

Answer 3

XEROPHTHALMIA (ocular manifestations)

Abnormal dryness of conjunctiva + cornea of the eye with inflammation

Question 4

What is vitamin A needed for?

Answer 4

Formation of rhodopsin, photoreceptor pigment in the retina (important for vision)
Antioxidation
Gene transcription
Differentiation of epithelial cells into specialised tissue
Prevent squamous metaplasia (hence prevent formation of Bitot spots)

Question 5

What causes dryness of the conjunctiva and cornea in xerophthalmia? How does this progress?

Answer 5

Keratinisation of the eyes.

Conjunctivae develop oval/triangular spots (Bitots spots) + cornea becomes cloudy + soft.

Question 6

List causes of vitamin A deficiency

Answer 6

Inadequate intake
Fat malabsorption
Liver disorders (liver stores vit A)

Question 7

Describe the epidemiology of vitamin A deficiency

Answer 7

Common in Asia where rice is staple food: completely lacks beta carotene (precursor to vit A)
Rare in UK

Question 8

Describe onset and symptoms of vitamin A deficiency

Answer 8

Starts off with night blindness
As diseases progresses, cornea becomes hazy + can develop erosions which can lead to its destruction + complete blindness.
Can also get drying, scaling + follicular thickening of the skin due to keratinisation of skin
Respiratory infections due to keratinisation of mucous membranes in respiratory tract.

Question 9

List 7 signs of vitamin A deficiency

Answer 9

Night blindness, which may cause injuries 
Bitots spots on conjunctiva
Corneal xerosis: cornea appears dry + dull
Corneal ulcerations
Keratomalacia: last stage of xerophthalmia; softening of cornea, followed by perforation of eyeball + blindness
Dry skin
Dry hair

Question 10

What investigations are performed for vitamin A deficiency?

Answer 10

Check sight in darkness
Serum retinol binding protein
Zinc levels: zinc deficiency can interfere with production of retinol-binding protein
Iron studies: can affect metabolism of vitamin A
FBC: for anaemia or infection

Question 11

Describe management of vitamin A deficiency

Answer 11

Treat with vitamin A supplements 

Re-educate + monitor diet

Question 12

What is the prognosis of vitamin A deficiency?

Answer 12

Good if treated early, before blindness progresses 

Question 13

Give 2 complications of vitamin A deficiency

Answer 13

Blindness

Respiratory infection