Vita a

VITAMIN A

• Soumya Ranjan Parida

• Basic B.Sc. Nursing 4th year

• Sum Nursing College

Introduction

• Necessory nutrient

• Present mostly in animal tissues.

• Vita. A deficiency is most common cause of blindness that is preventable (may be irreversible)

• About 10000 childern/yr become blind in india due to deficiency

Physiology• Vitamin A is sub gp of retinoids

Retinol - vita A alcohol

Retinyl ester - vita A ester

Retinal - vita A aldehyde

Retinoic acid - vita A acid (most active form)

Physiology

• Beta-carotene- provitamin A

• Found in vegetables.

• Converted in retinol in intestinal wall.

• Retinol & carotene both are fat soluble.

• Stored in liver as retinyl palmitate.

• Retinol is transported in blood,bound to retinol binding protein(RBP).

sources• Retinol-

Rich – cod liver oil,shark liver oil & liver

Moderate- butter, ghee, egg yolk

• Carotene-

Best- red palm oil

Good- carrots, green leafy & yellow red vegetables,ripe mangoes, papaya .

Functions of vita A

1. Necessory for dim light vision.• The mojor difference between visual pigment in

Rods (Rhodopsin) & Cones (Iodopsin) is nature of the protein bound to retinol.

• In dark –11-trans retinol covert in 11-cis form by the help of enzyme retinene isomerese which then combines with opsin to form rhodopsin.This process is vita.A dependent.so patients with vita.A deficiency have delayed dark adaptation.

2. vita.A is necessory for membrane stability. Its deficiency as well as excess causes rupture of lysosomal membranes.

3. play a role in keratinization, cornification & mucous formation.

4. Deficiency causes basal cell proliferation hyperkeratosis & stratified sqamous epithelium formation in respiratory, urinary & other organs which causes increased incidence of infection in these areas.

5. Retinol enhance the humoral immune response.beta-carotine has got antioxident property.

6.role in retinitis pigmentosa &protoporphyria

7.In experimental animals it decreases the incidence of epithelial tumors.

8.deficiency also causes loss of appetite, loss of weight, eye lesions, disruption of reproductive process.

Clinical features• Ocular 1.Night blindness

2.Conjuctival xerosis- dryness, loss of transperancy,thicking, wrinkling, pigmentation, acumulation of debris.

3. Bitot’s spot – small plaque with silvery grey hue & foamy surface, triangular,raised surface, in bulbar conjectiva usually near limbus on temporal side.

Clinical feature:cotinue….

• 4.Corneal xerosis

• 5. Corneal ulceration• 6. Kertomalacia – rapid & characterstic

softening of a part or whole of cornea.

WHO classification of Xerophthalmia

• Primary signs

X1A-Conjuctival xerosis

X1B-Bitot’s spots

X2-Corneal xerosis

X3A-Corneal ulceration

(<1/3 of cornea)

X3B-Corneal ulceration

(> 1/3 of cornea)

• Secondary signs

XN-Night blindness

XF-Fundal changes

XS-Corneal scarring

Other menifestations• Retardation of mental & physical growth.

• Apathy

• Anaemia

• Hepatosplenomegaly

• Dry, scaly & hyperkeratosis of skin.

• Pyuria or hematuria.

• Raised ICT

• Hydrocephalus with or without cranial nerve palsy

Causes of deficiency• Age- young children & males

• Absorption defects- fat malabsorption, cystic fibrosis

• Disorders of metabolism- diabetes mellitus, enzyme deficiency

• Cirrhosis, hepatitis, thyrotoxicosis

• Poor intake of vita.A,low fat diet

• Enviormental factors-drought,femine

• Infection & infestations

Treatment• VITAMIN A (oral) 50,000 iu- age < 6 months 1 lac iu- age 6-12 months 2 lac iu- age > 1 year On 1st day ,next day and 4 weeks later .• Parentral,water soluble vita.A given in ½ or

¾ of oral if impaired oral intake, persistant vomiting & severe malabsobtion

• Symptomatic treatment of associated condition to be given.

Prevention

• Nutritional & dietory education to mothers.• 1 lac IU vita.A to infant at 9 month of age with

measles vaccine & 2 lac IU at 18,24, 30 ,36 month of age.

• Prompt treatment & periodic follow up of children.

• Recommended intake 300-400 microgram daily• Periodic deworming.

Hypervitaminosis A

• ACUTE- ingestion of 3 lac IU or more• Nausea, vomiting, drowsiness, buldging of

fontanella, diplopia, papilledema & other symp. Suggest brain tumor.

• CHRONIC- ingestion of excessive doses for several weeks & months.

• Anorexia, pruritus & lack of weight gain, long bones may show hyperosteosis.

THANKS