VITAMIN-A STATUS IN THE INSTITUTIONALIZED ELDERLY - CRITICAL ANALYSISOF 4 EVALUATION CRITERIA - DIETARY VITAMIN-A INTAKE, SERUM RETINOL, RELATIVE DOSE-RESPONSE TEST (RDR) AND IMPRESSION CYTOLOGY WITH TRANSFER(ICT)

Infraclinical vitamin A deficiencies may be health-threatening for eld erly people, yet they are difficult to assess unequivocally in this po pulation. In this study, we evaluate the vitamin A status of an elderl y institutionalized population (49 subjects, 83.6+/-6.1 years of age), by examining four different criteria: the dietary vitamin A intake, t he retinol concentration in serum, the relative dose-response test and the impression cytology with transfer. The incidence of infra-clinica l deficiencies was estimated to be 55% by examining dietary vitamin A intake, 21% by using the RDR test, 6% by the ICT and 2% from serum ret inol values. a These variations are not due to the choice of threshold values for each of the methods, yet rather to poor correlations betwe en the results given by these methods. Canonical correlation analyses indicate that some parameters related to retinol secretion from the li ver including Zn, prealbumin and retinol-binding protein, can affect i ndividual patient response towards the different methods. Validation o f the RDR test in this elderly population was not successful because o f poor reproducibility and moderate correction of RDR-detected vitamin A deficiencies by vitamin A supplementation. The method chosen for th e determination of vitamin A status in elderly people must be carefull y evaluated to account for possible age-related changes in the patient response to the method employed In the institutionalized elderly popu lation examined in this study, we observed a low vitamin A intake, whe reas serum retinol and ICT are within normal ranges and while RDR test 's responses appear too variable to draw any conclusion.