Vitamin A deficiency diseasesContents1. biochemistry of vitamin A2. metabolism vit A3. functions of vitamin A4. epidemiology of vitamin A deficiency5. clinical manifestation of vit A deficiency6. Other factors involved in xerophtalmia7. general management of vit A deficiency

Biochemistry of vit AIt is a fat soluble vitamin which is found in four different structural forms. These are retinol, retinal, retinoic acid and B-carotene.-mechanism of action

Metabolism of vitamin AConcentration of vit A in d/f dietary sources

animal foodsIU/100mg or ml Plant foods IU/100ml or mg

Fish liver oil 100,000 Red palm oil 50-100,000

Animal liver 10,000 Carrot 10,000

Butter 3,000 Spinach 10,000

Cheese 1,500 Sweet potatoes 5,000

Kidney 1,000 Apricots, mangoes 2,000

Eggs 1,000 Tomatoes 1,000

Fish 200 Green beans 1,000

Fresh milk 150 Yellow maize 350

meat 20 Rise, white maize negligible

Normally retinol is more effectively emulsified and absorbedCooking improves the absorption of B-caroteneStored in the liver which can maintain serum level up to six monthsTransport of vit A from the liver is dependent on1. Store retinol in the liver2. RBP synthesis

Functions of vit A1. Maintenance of a healthy epithelial tissue2. Reproduction3. VisionEpidemiology of vit A deficiency

Causes about one million child death every yearEvery year ¼ to ½ million children are blindedXerophtalmia due to malnutrition almost affects childrenIt is the disease of the poorYoung children b/n the age of 6 months and 3 years are at a higher riskMostly associated with measles and PEM

Clinical manifestationsDeficiency affects all epithelial tissues.Changes noted on the epithelial tissues is1) Keratinization2) Loss of goblet cellsDepresses appetite and suppresses immunity.Young growing children are at higher risk1) Requirement per unit of body weight2) Children’s storage capacity is poor

Manifestations of vit A deficiency on the eyeThere are primary and secondary signsPrimary-specific for xerophtalmiaSecondary-not specific for xerophtalmia but are likely to indicate vitamin A deficiencyPrimary signsX1A conjunctival xerosisX1B Bitot’s spot with conjunctival xerosisX2 Corneal xerosisX3A Corneal ulceration with xerosisX3B KeromalaciaSecondary signsXN Night blindnessXF Xerophtalmia fundusXS Xerophtalmic scar

X1A Conjunctival xerosisChanges occur on the bulbar conjunctiva especially the exposed partsFeatures are1. dryness2. Increased pigmentation3. Creamy white derbiesThese features can be widespread or localized to a small area of the conjunctivaFully reversible with vit A supplementation

X1B Bitot’s spot with conjunctival xerosisA small plaque foamy to waxy (greasy) in material on the bulbar part of the conjunctiva nearly always in the inter palpebral fissure.Formed b/c the eye lids do not wipe the bulbar conjunctiva properly.Reversible with vitamin A supplementation.

X2 Corneal xerosisLess common than conjunctival xerosis, but highly specific sign.The surface looks rough ,dull & irregularFully reversible with early treatment

X3A Corneal ulceration with xerosisCharacteristic features of corneal ulceration caused by xerophtalmia are1. Both corneal and conjunctival xerosis are present2. Both eyes are involved to some extent3.The ulcers are in the central lower part of the cornea4.There will always be some corneal scaringIn severe cases it may destroy the eye

X3B KeratomalaciaThe last and most severe sign of xerophtalmiaIt has two striking features1. The onset is very rapid2. There is very little tissue reaction or inflammationMay result in phtisis bulbi or staphyloma formation.

Secondary signsXN Night blindnessVit A deficiency results in poor dark adaptation and poor night visionMost sensitive sign that appear before any corneal or conjunctival signsCan be detected through1. Electro retinography2. Dark adaptation tests

XF Xerophthalmia fundusPale yellow spots that appear especially near the course of retinal vessels and also retinal peripheryXS Xerophthalmic scarUsually bilateral & in the lower part of the cornea

Other factor involved in Xerophthalmia1. PEM2. Generalized infection3. Exposed ulcers4. Measles5. Herpes simplex6. Treatment by traditional healers

General management principles of vitamin A deficiency1. Correct underlying nutritional deficiency or underlying illness2.Give local eye treatmentAll eyes with evidence of corneal ulceration or eyes with risk of developing ulcer should be treated with topical eye drops, generally the eye care includesa. antibioticsb.antiviralC.padding an eyeD.closing the eyesE mydriaticsF. steroids SHOULD NEVER BE GIVEN

3. Vitamin A supplementationEmergency treatment of children with xerophtalmia or corneal ulceration is 200,000 iu at day one, the same dose at day two and two weeks laterFor children <1, give 100,000 IU

In severe corneal disease and potential malabsorption - an initial dose of 100,000 IU of water-miscible vitamin A intramuscularly

4. Recognize & avoid socioeconomic problems that has caused the disease

Prevention1. Distribution of massive dose capsulesChildren under one year…..100,000IU every 4-6 monthsChildren over one year……..200,000IU every 4-6 monthsChildren at birth …………..50,000IUMothers after giving birth…300,000IUPregnant & lactating mother…10,000IU daily for 2 weeks2. Fortification3. Nutrition and health education4. Immunization

-Immediate treatment of children with severe measles with 200,000 IU of vitamin A on 2 successive days