Osteoprotegerin (OPG) and receptor activator of nuclear factor-kappaB ligand (RANKL) are key factors in bone remodeling in patients with anorexia nervosa (AN) and osteopenia. The purpose of this study was to investigate basal serum levels of OPG, RANKL and leptin, as well as bone mineral density (BMD) measured by DEXA at lumbar vertebrae L1-L4, and their evolution during one year in two groups of patients with AN.
Group I included 10 adolescent girls suffering from malnutrition and secondary amenorrhea with an evolution of more than one year at the beginning of the study who received oral estrogen treatment throughout the follow-up period. Group II comprised 10 girls with malnutrition and secondary amenorrhea with an evolution of less than one year who received nutritional treatment only. All parameters were compared with those of a control group of 19 healthy, age-matched girls with normal BMI and regular menstrual cycles.
The OPG/RANKL ratio was significantly decreased (p<0.05) after 1 year in group I, a fact that was due to an increase (p<0.05) in serum RANKL values. A correlation between OPG/RANKL and BMD was found in group I at the beginning of the study (r = 0.95; p<0.001). Patients in this group showed lower BMD values (p<0.01), both at diagnosis and at the end of the study, than those of group II patients, who showed normal BMD values.
The decrease in the OPG/RANKL ratio in girls with AN could partly explain the increase in bone loss that occurs in these patients.