Exploration du statut vitaminique A

Vitamin A deficiency is still a major health issue in developing countries but is scarce in western countries. Signs of vitamin A deficiency or excessive intake appear late and early indicators for assessing abnormal vitamin A status have been elaborated. The best indicator is liver vitamin A concentration. The mostly used indicator is blood retinol concentration. Indicators are based on: (i) clinical signs of vitamin A deficiency, e.g. hemeralopia, (ii) functional methods, e.g. dark adaptative test, (iii) blood and tissue molecular markers, e.g. blood retinol concentration, and (iv) vitamin A load tests, e.g. relative dose response test. Interpretation of the results of these indicators should be done with an acute knowledge of the sensitivity limits and the interfering factors. It is fundamental to choose the adequate indicator with regard to the assumed vitamin A status and the expected confounding factors. It is also recommended to cross the results of several indicators to have a better assessment of vitamin A status.