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In a study by golden et al, 100 adolescent girls with anorexia nervosa and amenorrhea were entered into a treatment program that included medical, nutritional, and psychiatric interventions. An initial evaluation included physical examination, history, exercise pattern, and measurement of LH, FSH, estradiol, and prolactin. Within one year of treatment, two-thirds of the girls had resumption of menses that was correlated closely with their attaining about 90% of standard weight and about 2 kg above the weight at which the menses had been previously lost. Increases in serum estradiol levels (> 110 pmol/L) closely correlated with resumption of menses indicating restoration of hypothalamic-pituitary-ovarian function.
Establishment of a goal for weight gain is a universal element in a management plan for a patient with anorexia nervosa, and it should be based upon the clinician’s assessment of the patient’s weight loss. In a young patient, the weight lost would be added to the weight not gained during a period of expected growth; in older patients, the weight loss would stand alone. Depending on their starting points, patients may lose similar amounts, or percentages, of body weight and incur quite different deficits of energy stored in fat cells and of lean body mass. Loss of lean body mass particularly affects skeletal muscle and the heart, and it follows that restoration of those to normal will be a priority in management. As lean body mass is replenished, energy is also restored to fat cells, although often at a slower rate. It has also been clear that, in anorexia nervosa, the LH (luteinizing hormone) secretory pattern regresses to one usually seen in pre-puberty, and that recovery of mature reproductive function is substantially linked to the physical recovery process; a patient who has a well-balanced diet that only stabilizes her weight at a level that is well below her normal range will remain amenorrheic and at continuing risk for osteopenia.
In the clinical setting, the height and weight of a patient with anorexia nervosa are usually at very different percentile values, and the weight is usually below the fifth percentile, and dropping. The body mass index (weight in kilograms divided by height in meters squared) is easily calculated, and is apt to be less than fifth percentile, as well. Other measurements evaluate muscle mass and energy stores in fat cells more directly. Regarding muscle, a measurement of the mid-upper arm circumference is compared with national standards, and a 24-hour urinary creatinine assay is used to estimate muscle mass, or even better, lean body mass. Skinfold calipers measure subcutaneous fat cells in a variety of standard sites on the surface of the body, and the results are compared with standards or used to estimate percent body fat. As the authors of this article demonstrate beautifully, when the serum LH concentration, measured during the evaluation, is undetectable, it predicts delay in return of menstrual function after weight gain.
The patients in this study who resumed menstrual function within one year of follow-up had reached weights that represented a mean of 90.5% of standard body weight; of interest, they had lost an average of 11 kg during their illnesses and had regained an average of 6 kg. However, the patients who remained amenorrheic at one year of follow-up had lost 13.7 kg and had regained 6.3 kg. Assessment of percent body fat in both groups was noted to be within the lower normal range at the time of evaluation and at follow-up. Most members of the amenorrheic group maintained serum estradiol concentrations below 30 pg/mL.
This study provides strong support for recommending adequate weight gain in patients with anorexia nervosa, and for measurement of serum estradiol concentrations in those who gain but do not have return of menstrual function. It is possible that the latter have prolonged inactivation of the hypothalamic-pituitary-adrenal axis, and that they will need special consideration for additional weight gain and hormonal supplementation. (Dr. Anyan is Professor of Pediatrics and Head of Adolescent Medicine at Yale University School of Medicine.)