THE CLINICAL SIGNIFICANCE OF THE PLASMA VITAMIN A LEVEL

Abstract

The chemical determination of vitamin A in the blood has been simplified so that it can be carried out in any clinical laboratory. Apart from the changes of the plasma vitamin A in nutritional vitamin A deficiency there are well defined variations of the plasma vitamin A content in many diseases. These variations, not related to nutritional deficiency, appear more interesting since secondary, conditioned¹ or endogenous² vitamin deficiencies (due to processes within the organism) are as significant in medical practice as primary or exogenous due to reduced nutritional intake. Two questions arise: 1. What determines the plasmavitamin A level? 2. How may a knowledge of this level be useful to the clinician? We attempt to answer these questions on the basis of information gained from the literature and from observations on 2,673 vitamin A determinations on 454 patients. In a statistical evaluation a t value³ of 2.5