Comparison of ICHECK Fluoro Kit with High-performance Liquid Chromatography for the Assessment of Serum Retinol Concentration

Abstract

Objectives: Assessment of serum retinol of a population is a valuable mean for the study of vitamin A status (VAS). Portable kits may be an interesting alternative for the assessment of VAS in vulnerable populations. The aim of this study was to validate the ICHECK Fluoro device as an alternative for the assessment of serum retinol concentration Methods: Serum samples from 89 school-age children were analysed by HPLC after deproteinization and extraction phases. Analysis by ICHECK was undertaken after injection of serum into the reagent vials and manual vigorous mixing. After precipitation of the content of the vial, it was introduced into the reading chamber of the ICHECK Fluoro and analysed at 0 min (ICHECK0min) and 15 min later (ICHECK15min). Bland and Altman approach was applied to test the agreement. Results: Mean HPLC, ICHECK0min and ICHECK15min values were 421.2±106.0 µg/L, 423.1±118.3 µg/L and 413.2±107.6 µg/L, respectively. There was a significant difference between ICHECK0min and ICHECK15min values indicating a decrease of retinol in the vial solution (p<0.001). Comparison with HPLC showed a proportional bias of r=-0.038, p=0.73 for ICHECK0min and r=-0.024, p=0.82 for ICHECK15min. Fixed biases (HPLC minus ICHECK) for ICHECK0min and ICHECK15min were respectively -1.9±23.1 µg/l (p=0.45) and 8.0±22.7 µg/l (p=0.002). Conclusions: The ICHECK Fluoro showed concordant agreement with HPLC for the assessment of serum retinol. We recommend that the use of the kit be instantaneous directly after the precipitation phase. This study was performed with the support of Sight and Life and "Fondation Centrale Laitière pour la nutrition de l'enfant".