and vitamin E which are needed in the metabolism of vitamin A can also lead to the deficiency. Frequent infoction increases the requirement for the nutrients including vitamin A hence increases risk of deficiency. clinical features The clinical signs associated with Vitamin A deficiency depends on the stage or severity of the deficiency. t. Nightblindness, a functiona l sign character ized by difficulty in seeing in dim light 2. Conjunctiva! xerosis or drying of the conjunctiva 3. Bitot's spot-a cheesy, foamy whitish deposit usually in the temporal quadran t of the eye 4. Corneal xerosis (corneal crying) 5. Corneal ulceration 6. Keratomalacia-the most sever lesion characterized by the softening of the cornea Biochem ical Feat L1re 1. Serum retinal determination by high pressure liquid chromatography : Normal Low Deficient Treatment 2:20 µg/d L or 2: 0. 70 µmol/L 10-< 20 µg/d L or 0. 35-<0. 70 µmol/L <10 µg/d L or< 0. 35 µmol/L Treatment Schedule (WHO 1988): Inf-ants and ch1ldren-<8. 0 kg. Presd:loolers Immediately on diagnosis 100,000IU 200. 000IU Followlng day 100,000IU 4 weeks. tater 100,0001U 200;0001U Prevention and control There are several approaches to prevent and control vitamin A deficiency. 1. Prophylactic doses given every slx months Infants 6 months to <l year of age-100,000 IU 1-5 years-200,000 Il J Mother upon delivery-200,ooo IU 2. Give fortified foods 3. Health educati. on and horticulture 4. Nutrition educ;ition 5. Public health mea::.-ures to prevent infections 6. Combination of interventions 4. Iodine Deficiency Disorders Iodine deficiency dfaorders (IDD) refer to a spectrum of conditions associated with lack of iodine. These include goiter, ment,. land growth retardation, cretinism, abortion, stillbirth s, thyroid enlargement and slow decision m~ng in adults. 343 