A longitudinal study of metacarpal bone morphometry in anorexia nervosa

Osteoporosis is a known complication of anorexia nervosa. Although calorie and mineral malnutrition may contribute to changes in bone mass and morphometry, hypoestrogenism is thought to be the most important etiologic factor. In a seven-year longitudinal study of six women aged 19 to 35 years with adolescent-onset anorexia nervosa, the objective was to correlate menstruation and bone morphometry. At the onset of the study, five women were amenorrheic and had abnormal metacarpal bone morphometry. After seven years, three women remained amenorrheic and below 85% of ideal body weight. Anteroposterior roentgenographs of the nondominant second metacarpal taken at the beginning and end of the study revealed an increase in medullary canal diameter (p less than 0.03) and medullary area (p less than 0.04) and a decrease in combined cortical thickness (p less than 0.04) and percent cortical area (p less than 0.02). These findings suggest progressive endosteal resorption in the absence of compensatory periosteal apposition. Such bone remodeling characteristics are distinctly abnormal in this age group. The three women who regained menses showed up to one third less endosteal resorption and less cortical thinning than did the three women who remained amenorrheic. Resumption of menses may be an important milestone in preventing further cortical bone loss in anorexia nervosa.