Cause:Vit A deficiency, a fat-soluble vitamin
Pathophys:Necessary for visual pigment of eye; other tissue functions not known. Columnar epithelium changes to stratified squamous (keratinization) in trachea, urinary tract, conjunctiva. ß-Carotene and other carotenes are precursors
Sx:Poor growth in children; impaired vision day and night
Si:Keratinization of eye and Bitot spots on sclera (gray plaques); dryness of eyes and skin can be severe (Nejm 1994;330:994)
Increased mortality and morbidity from most infections including measles (Nejm 1990;323:160)