THE HALLMARK OF ANOREXIA NERVOSA (AN), WHICH OCCURS ALMOST EXCLUSIVELY IN WOMEN, IS AMENORRHEA ASSOCIATED WITH WEIGHT LOSS. WITHIN THIS PATIENT POPULATION, SEVERAL CATEGORIES HAVE BEEN DISTINGUISHED: GIRLS AT THE TIME OF PUBERTY; YOUNG WOMEN WHO INITIALLY STARTED TO DIET IN ORDER TO LOSE WEIGHT, IN SOME CASES FOR PROFESSIONAL REASONS, OR MERELY TO BE FASHIONABLY SLIM; AND WOMEN WITH FRANK PSYCHIATRIC DISEASE, USUALLY SCHIZOPHRENIA, WHO ARE GENERALLY OLDER. MOST PHYSICIANS RESERVE THE DIAGNOSIS OF AN TO THE FIRST CATEGORY OF PATIENTS, AND CRITERIA HAVE DRAWN UP TO DEFINE THE BORDERS OF THE SYNDROME. SUCH CATEGORIZATION, HOWEVER, IS LARGELY ARTIFICIAL, REFLECTING THE PRECONCEPTION OF THE INVESTIGATOR ABOUT THE ETIOLOGY MORE THAN A THOROUGH UNDERSTANDING OF THE SYNDROME. REGARDLESS OF CATEGORY, THESE PATIENTS EXHIBIT THE SAME CONSTELLATION OF SYNDROME: WEIGHT LOSS, AMENORRHEA, WHICH IN 25% OF CASES PRECEDES SIGNIFICANT WEIGHT LOSS, BRADYCARDIA, CONSTIPATION, LOW BLOOD PRESSURE, HYPOTHERMIA, COLD SENSITIVITY, HYPERACTIVITY, OCCASIONALLY GROWTH OF LANUGO HAIR ALL OVER THE BODY, YELLOW PALMS WITH HYPERCAROTENEMIA, SOME DEGREE OF DIABETES INSIPIDUS, AND IN VERY SEVERE CASES, EDEMA. THEREFORE THE TERM AN SHOULD BE ABANDONED AND BE REPLACED BY THE MORE DESCRIPTIVE TERM OF STARVATION- AMENORRHEA. THE INITIAL DISORDER IS TRIGGERED BY SOCIAL, ENVIRONMENTAL, AND PSYCHIC FACTORS THAT AFFECT CENTERS OF THE HYPOTHALAMUS, PERHAPS VIA MONOAMINE PATHWAYS, AND PRODUCE THE WEIGHT LOSS AND SUBSEQUENT ENDOCRINE CHANGES SECONDARY TO EITHER THE WEIGHT LOSS ITSELF OR FURTHER EFFECTS ON THE HYPOTHALAMUS. OVERALL, IT APPEARS THAT THE ENDOCRINE DISRUPTIONS IN AN ACT AS A PROTECTIVE MECHANISM. THYROID FUNCTION IS ALTERED TO PRODUCE A HYPOMETABOLIC STATE ALLOWING OPTIMAL USE OF LIMITED FOOD INTAKE. THERE IS A REGRESSION OF THE GONADAL AXIS WHICH PROTECTS FROM PREGNANCY AND PERHAPS EVEN MONTHLY BLOOD LOSS. FINALLY THERE IS NO EVIDENCE TO SUGGEST A PRIMARY PITUITARY DISORDER IN AN. IN THE PRESENT PAPER, WE WILL FOCUS ON THE SOME NEUROENDOCRINE AXES, SUCH AS HPG, HPA, HPT AND THE RELATED NEURATRONMITTERS.

The hallmark of ANOREXIA nervosa (AN), which occurs almost exclusively in women, is amenorrhea associated with weight loss. Within this patient population, several categories have been distinguished: girls at the time of puberty; young women who initially started to diet in order to lose weight, in some cases for professional reasons, or merely to be fashionably slim; and women with frank psychiatric disease, usually schizophrenia, who are generally older. Most physicians reserve the diagnosis of AN to the first category of patients, and criteria have drawn up to define thus the borders of the syndrome. Such categorization, however, is largely artificial, reflecting the preconceptions of the investigator about the etiology more than a thorough understanding of the syndrome. Regardless of category, these patients exhibit the same constellation of symptoms: weight loss, amenorrhea, which in 25% of cases precedes significant weight loss, bradycardia, constipation, low blood pressure, hypothermia, cold sensitivity, hyperactivity, occasionally growth of lanugo hair all over the body, yellow palms with hypercarotenemia, some degree of diabetes insipidus, and in very severe cases, edema. Until further insight has been obtained into this syndrome, the term AN should be abandoned and be replaced by the more descriptive term of starvation-amenorrhea. The initial disorder is triggered by social, environmental, and psychic factors that affect centers of the hypothalamus, perhaps via monoamine pathways, and produce the weight loss and subsequent endocrine changes secondary to either the weight loss itself or to further effects on the hypothalamus. Overall, it appears that the endocrine changes in An act as a protective mechanism. Thyroid function is altered to produce a hypometabolic state allowing optimal use of limited food intake, yet the hypothalamic pituitary thyroid axis remains intact if needed. There is a regression of the gonadal axis which protects from pregnancy and perhaps even monthly blood loss. Finally there is no evidence to suggest a primary pituitary disorder in AN. Primary Hypothalamic disorder associated with dysfunction in temperature regulation and water balance, remain to be alucidated.