Receptor activator of NF(Kappa)B ligand/osteoprotegerin (RANKL/OPG) system and osteopontin (OPN) serum levels in a population of apulian postmenopausal women.

AIM: Osteoporosis is a bone disease, characterized by a reduction of bone resistance; in postmenopausal period bone metabolism is imbalanced. Several parameters have been proposed as markers of bone metabolism; the attention have been recently placed on the receptor of activator of NF(Kappa)B ligand receptor (RANKL) and osteoprotegerin (OPG), namely RANKL/OPG system. The aim of this paper is to evaluate changes in postmenopausal women in serum concentration of OPG, RANKL, and their ratio (i.e. RANKL/OPG ratio), osteopontin (OPN), bone-type alcaline phosphatase (BAP), serum-N-Telopeptide of type I collagen (serum-NTX); and their correlations with bone mineral density (BMD).

METHODS: An Apulian population group of 163 native postmenopausal women were followed at the Osteoporosis Centre of Policlinico of Bari (Southenrn Italy). Patients were classified into 3 separate groups, according to T-score: osteoporotic, osteopenic and control group. Serum concentrations of OPG, RANKL, RANKL/OPG ratio, BAP and NTX have been calculated.

RESULTS: No differences were found in OPG and BAP values. Significant correlations were found in the osteopenic group between OPG and RANKL (negative), and between RANKL and OPN or serum-NTX, OPN and serum-NTX or RANKL/OPG ratio, BAP and serum-NTX, serum-NTX and RANKL/OPG ratio (positive). In the other groups a significant correlation was observed between BAP and NTX.

CONCLUSIONS: In postmenopausal women, important modifications of bone metabolism markers (i.e. RANKL, OPG and OPN) could be due to serious engagement of bone turnover, especially in the pre-osteoporotic phase. Low bone density in postmenopausal women should be identified as soon as possible, and urgent measures are needed to reverse the process. Parameters namely RANKL e OPG may become an important index for the evaluation of the activity of drugs against osteoporosis, old and new like AMG 162 (anti-RANKL action).