RESUMEN
Previous surveys have suggested that preschool children in the North and Northeast of Thailand are at risk of inadequate vitamin A nutriture. Therefore, vitamin A status was assessed in 996 children aged 2-6 years in the North and Northeast Thailand during the dry (Feb.-April) and rainy (Sept.-Nov.) seasons. Approximately 1 per cent of samples during both periods exhibited serum retinol concentrations below 10 mcg/dl with means (+/-SD) concentration of 29 +/- 9.8 mcg/dl in the dry season and 37 +/- 15.4 mcg/dl in the rainy season. About one fifth of the studied children showed abnormal CIC and depleted liver stores (RDR > 20%). High risk areas were ranked and corresponded well by these 2 indicators. Therefore, it is concluded that the magnitude of the problem estimated by RDR and CIC are a more precise measurement of marginal vitamin A status than serum vitamin A level alone and about one-fifth of preschool children in the North and Northeast regions of Thailand experience subclinical vitamin A deficiency.