Women in long-term recovery from anorexia nervosa show reduced bone strength and muscle force, according to research in The Journal of Clinical Endocrinology & Metabolism, although an increase in body mass over time can benefit bone health.
In a study of women from Switzerland with a history of anorexia nervosa, researchers measuring various bone characteristics found that the women showed reduced volumetric bone mineral density at 4% of tibia length and reduced cortical thickness at the 14% and 38% tibia sites when compared with matched controls, although some recovery is possible with time.
“The sum of these results indicates that an increase in body mass, after the acute phase of the eating disorder has remitted, is an important predictor of [volumetric bone mineral content] and volumetric BMD recovery,” the researchers wrote.
Sandro Manuel Mueller, PhD, of the University of Zurich in Switzerland, and colleagues analyzed data from 22 women with a history of anorexia nervosa (mean age, 50 years; mean body mass, 54.8 kg; mean disease duration, 8.1 years) who have remained in stable recovery for an average of 27 years, along with 73 controls matched for age and sex. Researchers used peripheral quantitative computed tomography (pQCT) to measure tibia length at the 4%, 14%, 38% and 66% sites, volumetric bone mineral content (BMC), BMD, strength-sprain index (SSIPOL), endosteal and periosteal circumference and cortical thickness, as well as bone area. Researchers also measured maximal voluntary ground reaction force with an exercise that included repeated one-legged hopping on the nondominant leg.
Researchers found that formerly anorexic women had an 11.6% lower maximal voluntary ground reaction force (P = .001), a significantly lower volumetric BMC at both 4% and 14% of tibia length, and an 11.9% lower BMI when compared with matched controls.
Researchers also noted a tendency toward a reduction in cortical thickness in the anorexia group, with a 7.2% reduction at the 14% site and a 5.4% reduction at the 38% site.
In addition, the current body mass of the anorexia group correlated positively with volumetric BMC at the 14% site (P < .001), suggesting that an increase in body mass after recovery can bring health benefits.
There were no measurable differences for bone parameters between groups at 66% of tibia length, according to researchers, although muscle and fat in this area was significantly reduced for the anorexia group when compared with controls.
“Altogether, these results support the presence of an osteopenic state of the bone in the distal part of the tibia in the anorexia test population,” the researchers wrote.
Researchers noted that the average age of symptom onset for the anorexia group was 16 years, which likely affected alterations in bone mass and geometry characteristics.
“Based on these characteristics, we may assume that the accretion of bone mass during the important postmenarchal phase of adolescence was hindered in the symptomatic anorexic girls due to hormonal imbalances, leading to higher endosteal circumferences at all measured sites of the tibia,” the researchers wrote. – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.