Alterations in Vitamin a and Thyroid Hormone Metabolism in Anorexia Nervosa and Associated Disorders
Curran, Joanne Marie
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Permalink
https://hdl.handle.net/2142/77441
Description
Title
Alterations in Vitamin a and Thyroid Hormone Metabolism in Anorexia Nervosa and Associated Disorders
Author(s)
Curran, Joanne Marie
Issue Date
1982
Department of Study
Food Science
Discipline
Food Science
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Health Sciences, Nutrition
Language
eng
Abstract
Vitamin A and thyroid hormone metabolism was investigated in subjects with anorexia nervosa. Subjects referred to the Eating Disorders Clinic were selected for the study if they had experienced a weight loss of (GREATERTHEQ) 15% of original body weight and had a basal metabolic rate (BMR) of (LESSTHEQ) -15%. Twenty-seven subjects were divided according to eating behavior, i.e., dietary restriction or bulimia; and by level of serum carotene. This subdivision resulted in three groups: Group I, dietary restricters, normal serum carotene; Group II, dietary restricters, elevated serum carotene; and Group III, bulimic, elevated serum carotene. All bulimic subjects fulfilling the initial criteria were hypercarotenemic. Data were compared to normal, healthy volunteers.
Methods used in the analysis included: retinoid and carotenoid profiles by HPLC; retinol binding protein (RBP) by radial immuno-diffusion; thyroid hormones T(,4), T(,3) and rT(,3) by RIA; BMR by collection of basal respiratory gas and subsequent CO(,2) and O(,2) analysis.
Retinol and RBP were normal in all subjects. In Groups II and III, the hypercarotenemic groups, retinyl esters were significantly higher than in the non-hypercarotenemic group. The carotenoid profile revealed an elevation in retinoid active carotenoids, especially (beta)-carotene in hypercarotenemic groups, whereas in non-hypercarotenemic groups, non-vitamin A active lycopene was the major carotenoid. Thyroid hormones, T(,4) and T(,3), were significantly lower in the hypercarotenemic groups relative to control, whereas there was a trend toward elevated rT(,3) in all groups relative to control.
Diet was excluded from the etiology of hypercarotenemia since there was no difference in dietary intake between Groups I and II. In subjects with AN there is an adaptive change in metabolism conserving tissue stores of protein and energy, clearly evidenced by the lowered metabolic rate. Elevated retinyl esters and serum carotene reflect a decreased tissue need or an actual change in the cellular metabolism of vitamin A. Once elevated, retinyl esters may effect thyroid hormone metabolism. The elevated esters may effect binding of thyroxine to transport proteins, uptake of T(,4) by peripheral tissue, and/or subsequent conversion of T(,4) to T(,3). An elevated rT(,3) concentration suggests an alteration in the conversion of T(,4) under these conditions to the less metabolically active form.
The results clearly suggest that the alterations in vitamin A and thyroid hormone status of patients with AN are interrelated.
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