MedWire News: Research highlights the negative impact of anorexia nervosa on the bone mineral density (BMD) of young women, and the importance of regaining weight.
"Bone loss in anorexic patients occurs at an early stage, and the factors influencing such bone loss are different at the spine and hip," report Isabelle Legroux-Gérot (Roger Salengro Hospital, CHU Lille, France) and co-authors.
The study included 146 women with anorexia nervosa, aged an average of 24.1 years. The patients were aged a mean of 18.4 years at onset of their illness and had an average disease duration of 5.6 years. The patients were amenorrheic for an average of 3.8 years, and at time of BMD measurement just 39.7% had regular menstrual cycles.
BMD was measured at baseline using underwent dual-energy X-ray absorptiometry (DXA), and again 1 (n=146) and 2 (n=89) years later. A raft of plasma bone and hormone markers were also measured in the patients.
At baseline, the women all had a body mass index (BMI) below 19 kg/m2, with an average of 15.4 kg/m2. At 1 year, 15.1% of patients had achieved a BMI above 19 kg/m2.
At first measurement of BMD, 22% of the patients had osteoporosis and 49.3% had osteopenia, with significant loss at the spine, total hip, and femoral neck.
After 1 year, the women showed significant bone loss at all three sites, compared with baseline.
In multivariate analysis, 41% of the variation in BMD at the spine was explained by duration of illness, and levels of bone-specific alkaline phosphatase (BAP), cross-linked carboxyterminal telopeptide type I collagen (ICTP), and triiodothyronine (T3). For the total hip, 12% of the variation in BMD was explained by levels of leptin, but no factor explained variation in BMD at the femoral neck.
At the 2-year follow-up, there was no significant change in BMD at the spine or femoral neck. Of note, women who were menstruating at the 1-year follow-up showed a significant improvement in BMD at 2 years for both the total hip and femoral neck. BMD gain at the total hip was also significantly predicted by a BMI greater than 17 kg/m2 at 1 year.
The authors therefore conclude: "In AN, weight and menstrual cycle recovery at 1 year remain indispensable for a favourable change in BMD at 2 years."
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