Refinement of the modified-relative-dose-response test as a method for assessing vitamin A status in a field setting: Experience with Indonesian children

Abstract

The modified-relative-dose-response (MRDR) test, which has been used extensively throughout the world for assessing vitamin A status, has been simplified. The major methodologic change resulting from the current studies in Indonesia is the use of graded standard doses of 3,4-didehydroretinyl acetate (DRA) based on the age range of the population of interest. Instead of a dose of 0.35 μmol/kg body wt, standard doses of 5.3 μmol for children younger than 6 y, 7.0 μmol for children between 6 and 12 y of age, and 8.8 μmol for adults and children > 12 y of age are suggested for field use. The acceptable time between administering the oral dose and obtaining a blood sample was validated as being 4-7 h in a group of children (n = 84) by taking two blood samples per child between 3 and 7 h after dosing with DRA. Furthermore, DRA in vitamin E-containing corn oil, with or without the addition of 4.6 mmol all-rac-α-tocopheryl acetate/L, was found to be stable for ≤ 18 mo at 2 °C and at -20 °C, but not at 22 °C or at 37 °C. When DRA was stored in amber glass vials, stability was affected more by temperature than by exposure to room light. In keeping with earlier studies in adults, the ratio of 3,4-didehydroretinol to retinol tends to be independent of body weight. Indeed, slower growing children (ie, those with a lower weight-for-age) may have a somewhat better vitamin A status than their heavier counterparts.