Effects of Anorexia Nervosa on Clinical, Hematologic, Biochemical, and Bone Density Parameters in Community-Dwelling Adolescent Girls

Abstract

Objective. Anorexia nervosa (AN) is an eating disorder that leads to a number of medical sequelae in adult women and has a mortality rate of 5.6% per decade; known complications include effects on hematologic, biochemical, bone density, and body composition parameters. Few data regarding medical and developmental consequences of AN are available for adolescents, in particular for an outpatient community-dwelling population of girls who have this disorder. The prevalence of AN is increasing in adolescents, and it is the third most common chronic disease in adolescent girls. Therefore, it is important to determine the medical effects of this disorder in this young population. Methods. We examined clinical characteristics and performed hematologic, biochemical, hormonal, and bone density evaluations in 60 adolescent girls with AN (mean age: 15.8 ± 1.6 years) and 58 healthy adolescent girls (mean age: 15.2 ± 1.8 years) of comparable maturity. Nutritional and pubertal status; vital signs; a complete blood count; potassium levels; hormonal profiles; bone density at the lumbar and lateral spine; total body, hip, and femoral neck (by dual-energy x-ray absorptiometry) and body composition (by dual-energy x-ray absorptiometry) were determined. Results. All measures of nutritional status such as weight, percentage of ideal body weight, body mass index, lean body mass, fat mass, and percentage of fat mass were significantly lower in girls with AN than in control subjects. Girls with AN had significantly lower heart rates, lower systolic blood pressure, and lower body temperature compared with control subjects. Total red cell and white cell counts were lower in AN than in control subjects. Among girls with AN, 22% were anemic and 22% were leukopenic. None were hypokalemic. Mean age at menarche did not differ between the groups. However, the proportion of girls who had AN and were premenarchal was significantly higher compared with healthy control subjects who were premenarchal, despite comparable maturity as determined by bone age. Ninety-four percent of premenarchal girls with AN versus 28% of premenarchal control subjects were above the mean age at menarche for white girls, and 35% of premenarchal AN girls versus 0% of healthy adolescents were delayed >2 SD above the mean. The ratio of bone age to chronological age, a measure of delayed maturity, was significantly lower in girls with AN versus control subjects and correlated positively with duration of illness and markers of nutritional status. Serum estradiol values were lower in girls with AN than in control subjects, and luteinizing hormone values trended lower in AN. Levels of insulin-like growth factor-I were also significantly lower in girls with AN. Estradiol values correlated positively with insulin-like growth factor-I, a measure of nutritional status essential for growth (r = 0.28). All measures of bone mineral density (z scores) were lower in girls with AN than in control subjects, with lean body mass, body mass index, and age at menarche emerging as the most important predictors of bone density. Bone density z scores of <−1 at any one site were noted in 41% of girls with AN, and an additional 11% had bone density z scores of <−2. Conclusions. A high prevalence of hemodynamic, hematologic, endocrine, and bone density abnormalities are reported in this large group of community-dwelling adolescent girls with AN. Although a number of these consequences of AN are known to occur in hospitalized adolescents, the occurrence of these findings, including significant bradycardia, low blood pressure, and pubertal delay, in girls who are treated for AN on an outpatient basis is of concern and suggests the need for vigilant clinical monitoring, including that of endocrine and bone density parameters.