Endocrine Abstracts

The aim of the reported study was to assess gene expression levels of the OPG/RANK/RANKL system in peripheral blood mononuclear cells (PBMC) after tibolone and hormonal replacement therapy (HRT) administered to patients with oestrogen deficiency symptoms and osteopenia or postmenopausal osteoporosis.

Material and methods: 74 women after menopause, aged 45–71 years, were enrolled into the study and randomly assigned to different medical therapies: HRT and tibolone. Patients of the control group received only calcium and vitamin D₃ supplements. Measurements of β-CTX (C-terminal Telopeptide of type 1 Collagene), osteocalcin, of RNA expression in PBMC cells, serum alkaline phosphatase concentrations, as well as of total serum calcium and phosphate levels and of their 24 h urine excretion rates were evaluated at every visit (at baseline and after 3, 6 and 12 months). Densitometry of the left hip and of the lumbar spine (LS) was done at baseline visit and after 12 months.

Results: The differences in gene expressions of RANKL and RANK were not significant during the study period and did not differ significantly between the groups. No OPG gene expression was observed in PBMCs of patients in any of the studied groups and at any time point. In the tibolone group, positive, statistically significant relationships were found between the differences in RANK and RANKL expression and changes of bone mineral density (BMD) of LS and femoral neck. The tendency of positive correlations (P=0.051) was observed between RANKL and RANK gene expression and total hip BMD in the patients treated with HRT. In a control group a significant positive correlation and a tendency of positive correlation were demonstrated, respectively between the alterations of RANKL gene expression and changes of trochanter BMD and between the changes of RANK gene expression and differences in osteocalcin concentrations (R^{^2}=0.193; P=0.078).

Conclusions: Both tibolone and HRT do not seem to cause significant changes in gene expression levels of OPG/RANK/RANKL in PBMCs during the first 12 months of treatment.