ALTERED GLYCOSYLATION OF PITUITARY GONADOTROPINS IN ANOREXIA-NERVOSA - AN ALTERNATIVE EXPLANATION FOR AMENORRHEA

To investigate the relevance of glycoprotein polymorphism to gonadotro pin bioactivity in vivo, plasma follicle-stimulating hormone (FSH) and luteinizing hormone (LH), 17 beta-estradiol (E(2)) testosterone and s ex hormone binding globulin (SHBG) levels in 17 amenorrheic women affe cted with anorexia nervosa (14-29 years) and 10 age-matched normally c ycling women were evaluated. Plasma FSH and LH levels were assayed usi ng radioimmunoassay (RIA) and immunoradiometric assay (IRMA) methods, before and after concanavalin A-Sepharose (Con A) affinity chromatogra phy. Significant RIA-IRMA differences in FSH and LH plasma values were present only in women with anorexia nervosa (p < 0.005). Moreover, in these patients both FSH and LH showed a reduced binding to the Con A, expressed as a percentage of unbound, suggesting altered glycosylatio n of these moieties. In conclusion, these findings hypothesize the inv olvement of glycosylation polymorphism in RIA-IRMA differences; suppor t the usefulness of both RIA and IRMA methods in FSH and LH evaluation , before and after Con A chromatography; and suggest a new pathogeneti c pathway to explain amenorrhea in anorexia nervosa.