title: Determination of a cut-off value for the molar ratio of retinol-binding protein to transthyretin (RBP:TTR) in Bangladeshi patients with low hepatic vitamin A stores.
abstract: The purpose of this study was to determine a cut-off value of the molar ratio of retinol-binding protein to transthyretin (RBP:TTR) to indicate marginal vitamin A (VA) deficiency. Plasma RBP and TTR were measured by radial immunodiffusion in two groups of patients, i.e., surgical patients with known hepatic VA stores, and a cohort of children residing in a malaria-endemic area of Papua New Guinea who had received placebo or 210 micro mol of VA every 3 mo for 9 mo. A RBP:TTR ratio < or =0.36 selectively detected five of seven patients (71% sensitivity) with hepatic VA stores < or =69.9 nmol/g of tissue (i.e., < or =20 micro g/g), indicative of marginal VA deficiency. Using this cut-off value, 28% (n = 245) of children from Papua New Guinea had marginal VA deficiency before supplementation. After 7 mo, a low ratio persisted in 29% (n = 92) of placebo-treated children but in only 11% (n = 83) of those receiving VA supplements (chi(2), P < 0.01). At the end of the study, 13 mo after initiation or 4 mo after the last dose of VA, the percentage of children with a low ratio was still lower (chi(2), P < 0.02) in the VA group, 42.5% (n = 113) than in the placebo group, 58.6% (n = 118). These results demonstrate that a cut-off value < or =0.36 is indicative of marginal VA deficiency and can be used as an indirect method of VA assessment.
authors.affiliation: Nutrition Department, The Pennsylvania State University, University Park, USA. fxr5@psu.edu
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Rosales
authors.forename: Kitty K
authors.initials: KK
authors.lastname: Chau
authors.forename: Marjorie H
authors.initials: MH
authors.lastname: Haskell
authors.forename: Anuraj H
authors.initials: AH
authors.lastname: Shankar
mesh_terms: D000328:Adult; D000368:Aged; D001459:Bangladesh; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D006801:Humans; D007223:Infant; D008099:Liver / Q000378:metabolism*; D008875:Middle Aged; D011228:Prealbumin / Q000378:metabolism*; D012016:Reference Values; D012177:Retinol-Binding Proteins / Q000378:metabolism*; D054839:Retinol-Binding Proteins, Plasma; D014801:Vitamin A / Q000378:metabolism*; D014802:Vitamin A Deficiency / Q000175:diagnosis*
chemical_list: D011228:Prealbumin; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma; D014801:Vitamin A