To the Editor.—
Several studies of serum vitamin A levels in patients with psoriasis have produced conflicting results.1-3 The current study utilizes data from a population-based examination survey to test the hypothesis that people with active psoriasis have lower serum vitamin A levels than control subjects free of psoriasis.Materials and Methods.—The First National Health and Nutrition Examination Survey (NHANES-I), conducted from 1971 to 1974, consisted of a probability sample of the US population. Details regarding the dermatologic examination have been described by the National Center for Health Statistics (NHCS), Hyattsville, Md.4This study also uses the results of a serum vitamin A assay that was performed as part of the survey.5 The mean vitamin A levels of white subjects graded by NHANES' examiners as having active psoriasis were compared with control subjects by the two-sample t test within age strata selected to minimize possible confounding
Safavi K. Serum Vitamin A Levels in Psoriasis: Results From the First National Health and Nutrition Examination Survey. Arch Dermatol. 1992;128(8):1130–1131. doi:10.1001/archderm.1992.01680180126023
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