Vitamin Deficiency (A,B,C,D,E,K)

Question 1

What is vitamin A used for?

Answer 1

• forms Retinal which combines with Opsin to form Rhodopsin.
• Rhodopsin is a GPCR found in photoreceptor cells and is responsible for vision.
• It is necessary for both scotopic vision (night vision) and photopic vision (colour vision).
• Vitamin A is important for the development of the immune system.
• Derivatives of Vitamin A (Retinyl phosphate) are used to synthesise mannose-containing glycoproteins.

Question 2

What are the sources of vitamin A?

Answer 2

Retinoids:
Liver, milk, butter, cheese and egg yolk.

Carotenoids:
Green vegetables, carrots and red/yellow fruits

Question 3

What vitamin A deficiency cause?

Answer 3

Xerophthalmia:
• XN: Night Blindness. Poor Vision in the darkness. No changes to the eye.
• XIA: Conjunctival Xerosis. This is drying of the conjunctiva.
• XIB: Bitot’s Spots. The build-up of keratin located superficially in the conjunctiva.
• X2: Corneal Xerosis. This is drying of the cornea.
• X3A: Corneal Ulceration < 1/3 of the Corneal Surface. The ulcer may have the appearance of a small, punched-out area in the cornea. The ulcer may have a more fluffy appearance. The eye often looks surprisingly white.
• X3B: Keratomalacia/ Corneal Ulceration > 1/3 of the Corneal Surface. The most severe form of Xerophthalmia. The cornea may become oedematous and thickened, and then melt away.
• XS: Corneal Scar.
• XF: Xerophthalmic Fundus. Structural damage to the fundus in the form of yellow and white dots in the retinal periphery.

*Vitamin A Deficiency is the leading cause of childhood blindness worldwide

Question 4

What are the causes of vitamin A deficiency?

Answer 4

• Inadequate Intake
• Fat malabsorption: Liver disease, biliary tree obstruction, pancreatitis.
• Inflammatory bowel disease
• Coeliac disease
• Cystic fibrosis

Question 5

How is vitamin A deficiency diagnosed?

Answer 5

• clinical features

* serum vitamin A levels

Question 6

What is the treatment for vitamin A deficiency?

Answer 6

• 30 mg of VA (retinol palmitate) for 2 successive days.
• 30 mg 2-4 weeks later.
• Treat the malnutrition.
• Treat the cause of malabsorption.

Prophylaxis:
• supplements
• fortification
• adequate dietary intake

Question 7

What is vitamin E used for?

Answer 7

main physiological role is its contribution to membrane stability

Question 8

What does a vitamin E deficiency cause?

Answer 8

results in (HNRI): 
• Haemolytic Anaemia due to oxidative damage to RBC. 
• Neurological Deficits: 
- Babinski Sign Positive 
- Absent Reflexes 
- Loss of vibration sensation 
- Loss of proprioception sensation 
• Retinopathy 
• Impairment of the immune response

Question 9

What are the causes of vitamin E deficiency?

Answer 9

• Abetalipoproteinaemia: A rare inherited disorder of fat metabolism that results in poor absorption of dietary fat and Vitamin E.
• Fat Malabsorption:
- Cystic Fibrosis
- Crohn’s Disease
- Liver Disease
- Pancreatic Exocrine Insufficiency
• Familial Isolated Vitamin E Deficiency –a rare autosomal recessive neurodegenerative disease, with features similar to Friedreich’s Ataxia.
*It does not result from a reduced dietary intake of Vitamin E

Question 10

How is vitamin E deficiency treated?

Answer 10

• treat underlying cause

* vitamin E supplements

Question 11

What is vitamin K used for?

Answer 11

• Vitamin K is a co-factor necessary for the production of blood clotting factors: 2, 7, 9, 10
• Vitamin K is changed to its active form in the liver by the enzyme Vitamin K epoxide reductase.
• Activated vitamin K is then used in the post-transational gamma carboxylation of certain enzymes involved in coagulation: Factors II, VII, IX, X, and protein C and protein S.

Question 12

What are some sources of vitamin K?

Answer 12

• green leafy vegetables and dairy products
• kale
• spinach
• mustard
• turnip

Question 13

What does a vitamin K deficiency cause?

Answer 13

coagulopathy:
• brusing
• petechiae
• bleeding
- prolonged PT
- normal/slightly elevated APTT
• GI and mucosal bleeding

Question 14

What are the causes of vitamin K deficiency?

Answer 14

• Nutritional deficiency –very rare 
• Vitamin K antagonists e.g. warfarin. 
• Antibiotics, which affect the microbiotal metabolism of vitamin K. 
• Fat Malabsorption 
- Bile duct obstruction 
- Cystic Fibrosis 
- Crohn’s Disease 
- Liver Disease 
- Pancreatic Exocrine Insufficiency 
• Neonatal: 
- Poor placental transfer of vitamin K 
- Little vitamin K in breast milk 
- No hepatic stores

Question 15

How is vitamin K deficiency diagnosed?

Answer 15

• coagulopathy
• prolonged PT, normal.slightly prolonged APTT
• low levels of vitamin K

Question 16

How is vitamin K deficiency treated?

Answer 16

• vitamin K supplements

* vitamin K injections

Question 17

What is vitamin C used for?

Answer 17

• Vitamin C (Ascorbic Acid) is a powerful reducing agent controlling the redox potential within cells
• Vitamin C is essential for collagen synthesis:
- It acts as an enzyme donor to hydroxylases –lysl and propyl hydroxylases.
- This is essential in the conversion of proline to hydroxyproline.
- This is essential for the synthesis of collagen

Question 18

What are the sources of vitamin C?

Answer 18

• fruits and vegetables
• citrus
*boiling vegetables reduces the amount of ascorbic acid

Question 19

What does vitamin C deficiency cause?

Answer 19

scurvy:
• Keratosis of hair follicles with ‘corkscrew’ hair
• Perifollicular haemorrhages
• Swollen, spongy gums with bleeding and loosening of teeth
• Spontaneous bruising
• Spontaneous haemorrhage
• Anaemia
• Failure of wound healing
• Features of Sjogren’s: dry mouth and dry eyes.
• Joint pain

Question 20

What are the causes of vitamin C deficiency?

Answer 20

always due to inadequate dietary intake:
• alcoholism
• living alone
• refugees
• low income
• chronic infection/inflammation

Question 21

How is vitamin C deficiency diagnoses?

Answer 21

• Scurvy can be diagnosed on the basis of low blood ascorbate levels.
• FBC to investigate for haematological conditions.
• Imaging of affected joints

Question 22

What is vitamin B1 used for?

Answer 22

• Thiamin Pyrophosphate is essential for the enzyme pyruvate dehydrogenase –an enzyme that is essential in the Link Reaction and the formation of Acetyl CoA.
• TPP is also a co-factor for enzymes in the Kreb’s Cycle: Alpha-Ketogluterate Dehydrogenase
• Thus, it is an essential factor in carbohydrate metabolism

Question 23

What are the sources of B1?

Answer 23

• seeds
• legumes
• cereals
• rice

Question 24

What does vitamin B1 deficiency lead to?

Answer 24

• Wernicke-Korsakoff syndrome
• Beriberi syndrome

Wet Beriberi:
Cardiac Sequelae:
• These can either be high-output cardiac failure with peripheral vasodilation peripheral oedema, dyspnoea, and orthopnoea.
• Low-output cardiac failure with lactic acidosis and peripheral cyanosis (Shoshin Beriberi).

Dry Beriberi:
• Distal peripheral polyneuropathy (particularly of the legs).
• It is characterised by:
- Paraesthesia
- Reduced deep tendon reflexes
- Progressive severe weakness with muscle wasting

Question 25

What are the causes/risk factors of vitamin B1 deficiency?

Answer 25

• chronic alcohol excess
• people who only eat polished rice
• starved patients
• patients with long-term parental nutrition (and no vitamin supplements)

Question 26

How is vitamin B1 deficiency diagnosed?

Answer 26

• low levels of eryhrocyte TPP

Question 27

What is the treatment for vitamin B1 deficiency?

Answer 27

• IV thiamine
• Mg2+, K+ and PO43- Replacement
• Alcohol cessation in chronic alcoholics