title: Studies on the application of the relative-dose-response test for assessing vitamin A status in older adults.
abstract: We investigated the time course and the reproducibility of the relative-dose-response (RDR) test for assessing vitamin A status in older adults. The maximum plasma retinol response to 480 retinol equivalents (RE) of retinyl palmitate in abnormal responses was at 6 or 7 h after dosing compared with the 5-h sampling interval recommended by others for younger adults and children. With respect to reproducibility, the diagnostic concordance of two RDR tests at 7-d intervals in 14 elders was 71%. In 29% of tests, one test was abnormal and the other normal. Linear regression of the two RDR values in these 14 subjects gave a correlation coefficient of -0.08. We conclude that the procedure for the RDR should be modified when applied to persons greater than 60 y of age, and that multiple repetitions of the test are needed to provide a stable indication of vitamin A stores in an elderly individual.
authors.affiliation: Center for Studies of Sensory Impairment, Aging and Metabolism (CESSIAM), Guatemala City, Guatemala.
authors.forename: J
authors.initials: J
authors.lastname: Bulux
authors.forename: E
authors.initials: E
authors.lastname: Carranza
authors.forename: C
authors.initials: C
authors.lastname: Castañeda
authors.forename: N W
authors.initials: NW
authors.lastname: Solomons
authors.forename: L J
authors.initials: LJ
authors.lastname: Sokoll
authors.forename: F D
authors.initials: FD
authors.lastname: Morrow
authors.forename: R M
authors.initials: RM
authors.lastname: Russell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001059:Apoproteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005215:Fasting / Q000097:blood; D005260:Female; D006166:Guatemala; D006801:Humans; D008099:Liver / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012177:Retinol-Binding Proteins / Q000378:metabolism*; D054839:Retinol-Binding Proteins, Plasma; D013997:Time Factors; D014801:Vitamin A / Q000008:administration & dosage* / Q000097:blood*
chemical_list: D001059:Apoproteins; C101326:RBP4 protein, human; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma; D014801:Vitamin A