A LOW MOLAR RATIO OF RETINOL-BINDING PROTEIN TO TRANSTHYRETIN INDICATES VITAMIN-A-DEFICIENCY DURING INFLAMMATION - STUDIES IN RATS AND A-POSTERIORI ANALYSIS OF VITAMIN-A-SUPPLEMENTED CHILDREN WITH MEASLES

To assess whether the molar ratio of retinol-binding protein (RBP) to transthyretin (TTR) is of utility in detecting vitamin A (VA) deficien cy during inflammation, we analyzed data from a rat model of endotoxin -induced inflammation and from a previously reported randomized, place bo-controlled trial of VA supplementation in children with acute measl es. In rats, both marginal VA deficiency and inflammation were indepen dent causes of low plasma REP (two-way ANOVA, P < 0.001), whereas plas ma TTR concentration was reduced only by inflammation (P < 0.001), The molar ratio of plasma REP to TTR was reduced (by similar to 50%) only in rats with marginal VA deficiency and inflammation (two-way ANOVA i nteraction, P < 0.01). Serum retinol concentration, C-reactive protein (CRP, an indicator of inflammation) and the RBP:TTR molar ratio were determined in children with acute measles at baseline and 2 wk after s ubgroups received a placebo or a 210 mu mol VA supplement. The ratio o f RBP:TTR was selectively reduced in children in the placebo group wit h low plasma retinol (<0.35 mu mol/L) and elevated CRP (>40 mg/L), In children with a low RBP:TTR molar ratio (<0.30) at baseline, the RBP:T TR ratio increased significantly 2 wk later only in the VA-treated sub group. These analyses provide evidence that, because REP is differenti ally reduced in comparison to TTR during VA deficiency, the combined d etermination of the concentrations of serum REP and TTR may provide a promising means of detecting VA deficiency during inflammation.