In 1922, at Johns Hopkins University in Baltimore, Professor McCollum discovered a factor, which has since been referred to as vitamin D, following the alphabetical order of the other vitamins identified up to that time. It is capable of curing rickets in children and osteomalacia in adults. Diseases in which, as we know from the first scientific descriptions published in London in the mid-seventeenth century, muscle involvement consisting of weakness and generalized hypotonia is associated with bone involvement, its main characteristic. Therefore, since the discovery of vitamin D, it has been associated not only with bone health but also with muscle health . Paradoxically, at present, there is no consensus on the potential beneficial effects of vitamin D supplementation on muscle function, balance and risk of falls, a situation highlighted in the last meta-analysis published by Bolland et al. , who review in 81 randomized clinical trials (RCTs) that include 53,537 participants the effect of vitamin D on fractures and falls as a primary outcome. The pooled analyses showed that vitamin D supplementation had no effect on falls (37 RCTs, n=34,144, RR=0.97, 95% confidence interval -0.93 to 1.02), what the authors concluded that “vitamin D supplementation does not exert significant effects in falls”, affirming that “potential future trials will probably not alter those conclusions, and that, therefore, there is little justification for the use of vitamin D supplements.Read More
Calcidiol levels and muscle function maintenance, functional capacity and bone mineral bone density in non-selected Spanish population
The aging process is associated with a loss of muscle mass and strength, as well as a decrease in bone mineral density (BMD), which can lead to reduced mobility, greater risk of falls and the appearance of fractures [1,2]. In recent years, special emphasis has been placed on maintaining an adequate vitamin D status to optimize muscle strength and BMD in order to reduce falls and fractures [3-5]. Although a recent meta-analysis questions the usefulness of vitamin D supplements to reduce the risk of falls, BMD decrease and fractures , there are sufficient arguments that demonstrate the importance of vitamin D on muscle and bone health. Vitamin D stimulates the absorption of calcium from the intestine and maintains the serum calcium levels that are required for normal bone mineralization and for the maintenance of muscle function . Several in vivo studies suggest vitamin D’s role in regulating muscle mass and its function. Observational studies show that vitamin D deficiency in the elderly is associated with reduced muscle mass and strength [8-10], lower physical performance [8,11], and increased risk of falls .Read More
Mechanical force is one of the most important stimuli that the bone receives to regulate bone mass, shape and microarchitecture. The endoskeleton reacts to an increase in load by forming more bone or decreasing its mass in the absence of mechanical stress . This is because the stimulation triggers the mechanotransduction process in which osteocytes, considered bone’s key mechanosensory cells, when stimulated, send chemical signals that affect the paracrine regulation of osteoblast and osteoclast behavior [2,3]. It also has been found to have an anti-apoptotic effect on osteocytes .
With mechanical loading, the expression of sclerostin, which is an inhibitor of the protein signaling pathway Wnt/β-catenin constitutively secreted by osteocytes, decreases thus causing an increase in osteoblastogenesis [5,6]. On the other hand, apoptotic osteocytes induce the secretion of the receptor activator for nuclear factor κ B ligand (RANKL), indirectly stimulating osteoclastogenesis . In addition, some chemokines, a family of chemotactic cytokines, could be involved in bone remodeling when expressed by bone cells and provide key signals to recruit different cellular subpopulations .
The determining role of a resorption marker, carboxyterminal telopeptide of collagen I, in assessing therapeutic compliance in patients treated with oral bisphosphonates
Osteoporosis is a metabolic disease characterized by low bone mass and microstructural deterioration of the bone tissue that leads to increased bone fragility. The main complication involves the appearance of fragility fractures . Osteoporotic fractures are an important health problem  associated with high healthcare costs . To prevent the appearance of fractures, different drugs are available that act on bone metabolism and are associated with reduced fracture risk . The most commonly used in Spain are bisphosphonates . However, in order to observe this protective effect, adequate therapeutic compliance is required . In osteoporosis, as in all chronic diseases, compliance is low. In a recent study conducted in Spain, the overall persistence per year after commencing osteoporosis drug is 47%, and at two years, close to 27% .Read More
Different development of serum sclerostin compared to other bone remodeling markers in the first year after a liver transplant
Solid organ transplantation is an effective alternative in the final stage of multiple chronic diseases, increasing patients’ survival. However, this improvement is associated with certain complications, such as a higher incidence of osteoporosis and an increased risk of fractures . Numerous studies have concluded that there is a loss of bone mass after transplantation, more marked between the first three and six months, which lasts up to a year after the same. Subsequently there is a stabilization and even recovery of bone mass in the two subsequent years [2-4].
Liver transplantation is considered an independent risk factor in the development of osteoporosis [1-3]. In the case of patients with a liver graft, the incidence of fracture is estimated at 10-43% , with the spine location being the most frequent [2-4]. Among the factors that contribute to the increased risk of osteoporosis and fractures in these patients are: prolonged treatment with immunosuppressants (mainly calcineurin inhibitors) [2,5-8] and glucocorticoids [9,10], vitamin D deficiency (very common due to malnutrition) and alterations in liver function found in most patients with cirrhosis [1-3].
In recent decades, vitamin D has attracted growing interest, not only in the medical field, but also among the general population. Initially, the evaluation of vitamin D was part of bone metabolism assessment when, for example, rickets or osteomalacia were suspected, or in populations at risk of osteoporosis . 25-hydroxyvitamin D (25-OHD) is the circulating metabolite of higher concentration and longer half-life, used to monitor the body status of vitamin D. Patients with chronic kidney disease and undergoing dialysis treatment are also controlled by measurements of the evaluation of this state . In this case, in addition to 25-OHD, the active metabolite of vitamin D, 1,25-dihydroxyvitamin D (1,25- (OH) 2D), produced mainly in the cells of the proximal tubule of the nephron.Read More
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