Bone Renewal in Partially Recovered AN Patients

Speedy and ongoing recovery
promotes bone density.

In terms of bone mineral density (BMD), the timing of AN couldn’t be worse. The onset of AN often occurs during adolescence, a peak time for bone growth and mineral buildup. Aided by nutritional deficiencies and hormonal abnormalities, peak bone mass, which usually is complete by age 20, may not be reached. Changes in the bone structure and persistent mineral deficits may follow, increasing the risk of reduced bone mass and osteoporotic fractures. And, recovery of BMD in persons with AN is a slow process that is dependent upon complex interactions between hormonal and nutritional factors.

Researchers at the University of Ulm, Germany, recently designed a follow-up study of patients with early-onset AN after discharge from the hospital, to assess the outcome and hormonally related effects on bone mineral and the relationship to lean body mass (Child Adolesc Psychiatry Ment Health 2010; 4:20). Dr. Ulrike ME Schulze and colleagues re-studied 52 female patients with early onset AN 3 to 9 years after they were discharged from the hospital. They evaluated the general outcomes of the patients, and also used dual-energy x-ray absorptiometry (DXA) to measure bone mineral content (BMC) and BMD, as well as lean and fat mass. The women were also tested for serum concentrations of leptin and insulin-like growth factor-1 (IGF-1). The researchers postulated that a good global outcome and weight gain would counteract bone mineral loss in these patients.

At follow-up, the patient’s current body composition was compared with baseline results, and the following were recorded: body mass index (BMI, or kg/m²), and the presence or absence of menstrual cycles and/or bulimia nervosa. Hormone replacement therapy was assumed if estrogens had been taken without interruption for at least 12 months before the follow-up study. Women who had exercised consistently for at least 9 months during the follow-up period were classified as physically active. The researchers also ordered tests for blood count, electrolyte balance and pancreatic, liver, kidney, thyroid and gonadal function. DXA scans recorded total BMC, lean body mass and fat mass.

Good bone accrual occurred in most women

At follow-up, half of the women (26) had good general outcomes (defined as BMI > 17.5 kg/m² and resumption of menses). Six (11.5%) continued to have symptoms of AN or BN. On physical examination, 35% of the former patients had skin signs of AN such as acrocyanosis or lanugo. Eight women had low triiodothyronine (T-3) levels; two had hyperthyroidism, and 19 had slightly elevated serum amylase levels.

For all 52 women, all essential body composition and bone mineralization parameters showed a considerable accrual. The duration of amenorrhea had a negative correlation with BMD but not with BMC. Regular physical activity tended to show a positive effect on bone recovery, but the effect of hormone replacement therapy was not significant. Serum leptin levels varied widely, and correlated with BMC and current body composition.

The authors concluded that bone mineral accrual was dependent on a speedy and ongoing recovery from AN. Leptin levels tended to respond immediately to the patient’s current nutritional status, but IGF-I serum concentrations corresponded more closely with the patient’s age and general recovery from AN.