CONJUNCTIVAL IMPRESSION CYTOLOGY FAILS TO DETECT SUBCLINICAL VITAMIN-A-DEFICIENCY IN YOUNG-CHILDREN

Thirty-four asymptomatic children, ages 5-35 mo, were studied to compa re the conjunctival impression cytology technique with the relative do se response test in detection of subclinical vitamin A deficiency. Con junctival smears were collected from the infero-temporal-bulbar conjun ctiva of each eye with a strip of cellulose acetate filter paper and t ransferred onto a glass slide. Venous blood was drawn at 0 and 5 h aft er administration of an oral dose of 1000 mu g of retinol palmitate (r elative dose response test). An increase in serum retinol concentratio n (greater than or equal to 20%) in the 5-h value was considered indic ative of an inadequate liver store of vitamin A and hence subclinical vitamin A deficiency. Of the 34 children, 26 (76.5%) had moderate to s evere protein-energy malnutrition. Only three children (9%) had abnorm al conjunctival impression cytology, whereas 23 (68%) had abnormal rel ative dose response. Even more striking was the finding that only two of the 23 children with abnormal relative dose response had abnormal c onjunctival impression cytology. The results suggest that the conjunct ival impression cytology test has poor agreement with the relative dos e response test results in assessing vitamin A status in young childre n. If relative dose response is considered an acceptable reference met hod for assessing vitamin A status, then the conjunctival impression c ytology test cannot be considered a valid measure of subclinical vitam in A deficiency in this population.