Endocrine Abstracts

Objectives: We assessed the implications of PINP (procollagen type I N-terminal propeptide), NTX (cross-linked N-telopeptides of type I collagen), E₂ (estradiol), calcium (Ca²⁺), phosphorus (PHOS(2−)), and their correlation with bone mineral density (BMD) in the process of bone remodeling of postmenopausal osteoporosis.

Methods: The study was performed on two groups of women with postmenopausal osteoporosis (with different degrees of estrogenic deprivation): group I (n=48, with <15 years of estrogenic deprivation) and group II (n=26, over 15 years of estrogenic deprivation), compared with a control group (n=20, postmenopausal women without osteoporosis). Serum levels of the ions were measured by VitrosSlides quantitative technique. Bone levels of these ions were assessed by bone flame atomic absorption spectrometry (FAAS). BMD was measured by dual-energy X-ray absorptiometry (DXA) technique. Serum levels of the enunciated markers were measured by ELISA technique.

Results: Serum PINP levels were increased in group I (+17.2%, P<0.001), and decreased in group II (−66.2%, P<0.001), as compared to the controls. Serum levels of NTX were significantly higher (group I: +33.5%, P<0.001 and group II: +58.3%, P<0.002) vs control. Serum Ca²⁺ and PHOS(2−) levels were increased in group I (+12.06%, P<0.005 - calcium and +36.78%, P<0.004 - phosphorus), and decreased in group II (−85.65%, P<0.006-calcium and −57.22%, P<0.003 - phosphorus). The bone levels of these ions were lower in both groups (P<0.001, respectively P<0.002, vs controls). Estradiol levels were significantly lower in both groups (P<0.01, respectively P<0.02), associated with low BMD.

Conclusions: The levels of these ions increase transitory in serum, as a result of bone demineralization through hidroxiapatite microcrystal solubilization and mobilization of these ions in the circulation. This imbalance produces a decrease in bone formation and an increase in bone resorption, leading to bone demineralization and increased risk for osteoporotic microfractures.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.