The Vaginal Smear Method of Determining Vitamin A

Abstract

60 female rats were depleted of their stores of vitamin A and then fed graded doses of carotene. Changes in vaginal smears were observed simultaneously with changes in weight and in the ophthalmic condition. Typical "low A smears" were frequently observed before the appearance of other symptoms of avitaminosis, and more carotene was necessary to restore the smears than to cure the other deficiency symptoms. On 3 to 5 [gamma] carotene per day ophthalmia was cured and growth restored, but the smears remained abnormal. On higher levels of carotene all symptoms were cured. The vaginal smear method is suitable for the determination of vitamin A, with reservations.