The molar ratio of serum retinol-binding protein (RBP) to transthyretin (TTR) is not useful to assess vitamin A status during infection in hospitalised children

Abstract

Objective: To assess the usefulness of the molar ratio of serum retinol-binding protein (RBP) to transthyretin (TTR) to determine vitamin A (VA) status during infection.

Design: We took advantage of previously collected data during a randomised double-blind, placebo-controlled clinical trial to conduct a secondary analysis of the RBP/TTR ratio and its relationship to infection and VA status. In this clinical trial, children were randomly assigned to one of three groups and received either one single oral high dose of VA (200 000 IU) on the day of admission and subsequently a placebo daily until discharge or daily oral low doses of VA (5000 IU) from admission until discharge or a placebo daily from admission until discharge.

Setting: Lwiro pediatric hospital, Province of South Kivu, Democratic Republic of Congo.

Subjects: A total of 900 children aged 0-72 months hospitalised consecutively between March 1994 and March 1996.

Main outcome measures: RBP/TTR molar ratio after 7 days hospitalisation.

Results: After 7 days hospitalisation, molar RBP:TTR ratio (mean+/-s.d.) of infected children (C-reactive proteins>10 mg/l) was 0.67+/-0.31 in the high-dose group (n=81), 0.74+/-0.44 in the low dose group (n=71) and 0.73+/-0.39 in the placebo group (n=81). These values did not differ significantly (one-way ANOVA P=0.472). In patients with baseline serum retinol concentrations<0.70 micromol/l, changes in RBP:TTR ratio between admission and day 7 were not statistically different in the three groups (one-way ANOVA P=0.548).

Conclusions: In this population of malnourished hospitalised children, molar RBP:TTR ratio does not appear to be useful to assess VA status during infection.

Sponsorship: Our research was partially supported by a grant from the Fonds de la Recherche Scientifique et Médicale (contract 3.4505.94) and the David and Alice Van Buuren Foundation.