Circulating Serotonin as Bone Remodelling Marker in Women

Abstract

The bone remodelling represents a physiological reparative process which is constant into the human body. The underlying aspects include osteoclasts activity (for instance areas of bone are resorbed) and osteoblasts activity that fill with new bone the resorbed zones (bone formation). Normally there is a balance between these two mechanisms. By this continuum a major contribution to the quality of bone is achieved[1,2]. The bone turnover is influenced by age: in time resorption become more pronounced that bone formation causing a net loss of bone, and thus damaging the skeleton integrity. In women a secondary factor is essential: the timing of menopause and the consecutive exposure to estrogens deficiency[2,3]. Overall the bone quality suffers by affecting the micro-architecture, decreasing the mineralisation and increasing the cortical porosity[3,4]. The process of remodelling is best assessed by bone markers levels. They are biochemical parameters with blood or urinary assay that offer to the clinician a rapid and facile clue regarding the bones turnover status (see Figure 1)[5,6]. They predict the fracture risk especially in some menopausal population but the references levels still vary so a specific pattern cannot actually be predicted[5,6]. Some persons with menopausal osteoporosis may have normal bone markers while others display a high status of bone turnover bio-markers. The data regarding the correlation to bone mineral density as assessed by central DXA (Dual Energy X-Ray Absorptiometry) are heterogeneous but usually in subjects with osteoporosis higher bone resorbtion markers are found compare to control group[7]. Overall the biochemical markers are not recommended for the diagnosis of osteoporosis by any guideline. They may become useful in follow-up the patients who started anti-osteoporotic drugs especially if they had a high values at the beginning of therapy[5,6,7]. An extended usefulness is seen in clinical trials in order to express the medication effects. However the routine use in not recommended and the intra-individual variations are difficult to “translate” in everyday practice[5,6,7].