Vitamin Deficiency (A,B,C,D,E,K) Flashcards
What is vitamin A used for?
- 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.
What are the sources of vitamin A?
Retinoids:
Liver, milk, butter, cheese and egg yolk.
Carotenoids:
Green vegetables, carrots and red/yellow fruits
What vitamin A deficiency cause?
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
What are the causes of vitamin A deficiency?
- Inadequate Intake
- Fat malabsorption: Liver disease, biliary tree obstruction, pancreatitis.
- Inflammatory bowel disease
- Coeliac disease
- Cystic fibrosis
How is vitamin A deficiency diagnosed?
- clinical features
* serum vitamin A levels
What is the treatment for vitamin A deficiency?
- 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
What is vitamin E used for?
main physiological role is its contribution to membrane stability
What does a vitamin E deficiency cause?
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
What are the causes of vitamin E deficiency?
• 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
How is vitamin E deficiency treated?
- treat underlying cause
* vitamin E supplements
What is vitamin K used for?
- 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.
What are some sources of vitamin K?
- green leafy vegetables and dairy products
- kale
- spinach
- mustard
- turnip
What does a vitamin K deficiency cause?
coagulopathy: • brusing • petechiae • bleeding - prolonged PT - normal/slightly elevated APTT • GI and mucosal bleeding
What are the causes of vitamin K deficiency?
• 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
How is vitamin K deficiency diagnosed?
- coagulopathy
- prolonged PT, normal.slightly prolonged APTT
- low levels of vitamin K
How is vitamin K deficiency treated?
- vitamin K supplements
* vitamin K injections
What is vitamin C used for?
• 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
What are the sources of vitamin C?
• fruits and vegetables
• citrus
*boiling vegetables reduces the amount of ascorbic acid
What does vitamin C deficiency cause?
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
What are the causes of vitamin C deficiency?
always due to inadequate dietary intake: • alcoholism • living alone • refugees • low income • chronic infection/inflammation
How is vitamin C deficiency diagnoses?
- Scurvy can be diagnosed on the basis of low blood ascorbate levels.
- FBC to investigate for haematological conditions.
- Imaging of affected joints
What is vitamin B1 used for?
- 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
What are the sources of B1?
- seeds
- legumes
- cereals
- rice
What does vitamin B1 deficiency lead to?
- 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
What are the causes/risk factors of vitamin B1 deficiency?
- chronic alcohol excess
- people who only eat polished rice
- starved patients
- patients with long-term parental nutrition (and no vitamin supplements)
How is vitamin B1 deficiency diagnosed?
• low levels of eryhrocyte TPP
What is the treatment for vitamin B1 deficiency?
- IV thiamine
- Mg2+, K+ and PO43- Replacement
- Alcohol cessation in chronic alcoholics
