Impression cytology: a practical index of vitamin A status.

Impression cytology was performed on 148 Indonesian preschool children of whom half had mild xerophthalmia and half were age-matched control subjects. Subjects were divided into subgroups that reflected the degree of confidence in their true vitamin A status as determined by serum vitamin A levels, clinical examination, and response to therapy. Impression cytology was considered normal if goblet cells were present and abnormal if they were absent. Thirteen of 14 (93%) children with vitamin A-responsive Bitot's spots and night blindness with base-line serum vitamin A less than 20 micrograms/dL (0.70 mumol/L) (group 1, definite deficiency) had abnormal cytology. In contrast, 17 of 18 (94%) children with normal ocular exam and serum vitamin A greater than 25 micrograms/dL (0.87 mumol/L) (group 7, least likely deficient) had normal cytology. Importantly, 12 of 26 (46%) clinically normal children with serum vitamin A levels less than 20 micrograms/dL (0.70 mumol/L) had abnormal impression cytology.