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Endocrine Disorders, Contraception, and Hormone Therapy during Pregnancy
Published in “Bert” Bertis Britt Little, Drugs and Pregnancy, 2022
Parathyroid glands (~4) are located along the posterior border of the thyroid gland. Their function is primarily in the regulation of bone mineral metabolism. Parathyroid hormone (PTH) maintains extracellular fluid calcium concentration. During pregnancy, calcium requirements increase to 3 to 4 times the non-pregnant daily requirement, especially during the latter half of gestation when most of the fetal bone mineral is deposited. Calcium and phosphorus are actively transported across the placenta, resulting in lower maternal serum calcium concentration, an increase in PTH secretion, and decreased calcitonin production (Schedewie and Fisher, 1980). During gestation, 1,25 dihydroxy vitamin D levels and intestinal absorption of calcium increase strikingly (Bouillon and Van Assche, 1982; Heany and Skillman, 1971; Kumar et al., 1979).
Chronic Fatigue Syndrome/ Myalgic Encephalomyelitis in Children and Young People
Published in Cathy Laver-Bradbury, Margaret J.J. Thompson, Christopher Gale, Christine M. Hooper, Child and Adolescent Mental Health, 2021
It is important for the young person and their family to understand that fatigue and weakness are exacerbated by excessive rest and inactivity. The effects of inactivity are: Significant effects occur within one to four weeks of bed rest.Reduced muscle volume and strength.Reduced muscle protein and increased connective tissue.Reduced bone mineral density.Joint stiffness.Reduced BMR.Altered white cell function.Changes in immune response.Effect on mood and circadian rhythm.
Osteoporosis
Published in Peter V. Giannoudis, Thomas A. Einhorn, Surgical and Medical Treatment of Osteoporosis, 2020
Ippokratis Pountos, Peter V. Giannoudis
The role of dietary calcium and dairy product intake in the development of osteoporosis has not been fully explored. Nevertheless, it is currently thought that adequate calcium intake improves bone mineral density. Ample calcium intake during childhood and adolescence leads to a higher peak bone mass, which in turn can be considered as an extra deposit for the subsequent years in life (1). In adulthood and especially in postmenopausal women, calcium depletion is associated with increased bone resorption (2). The serum total calcium levels can be within range even in patients with low calcium intake due to compensatory mechanisms; however, the identification and treatment of patients with hypocalcemia could potentially lead to a reduction of bone resorption. Albumin adjustment of total calcium can be useful in correcting total calcium levels skewed by abnormal albumin levels. Ionized calcium measurement can give a more accurate indication of calcium homeostasis.
Finite element analysis of fixation effect for femoral neck fracture under different fixation configurations
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Haipo Cui, Wenqing Wei, Yinlin Shao, Kewei Du
Oden et al. (1999) reported that the average load in the case of ITS fixation was higher than that in the case of positive triangle screw fixation; moreover, the former case yielded better tensile and compressive strain capacities, and there was no significant difference in torsional resistance between the two cases. Samsami et al. (2019) demonstrated that DHS fixation was a more effective approach than cannulated screws and proximal femoral locking plate techniques for vertical femoral neck fractures in young patients. Zhang et al. (2017) illustrated that, compared to using multiple cannulated screws, DHS fixation required larger skin incisions and more soft tissue dissection; however, it was associated with lower rates of fixation failure, reoperation, and overall rate of postoperative complications. Existing studies have reported on the FEA of femoral neck fracture fixation for many internal fixation configurations, but the effect of internal fixation for osteoporosis patients is rarely mentioned. It should be noted that bone mineral density can affect bone biomechanics (Zhuang et al. 2019). Femoral neck fracture is more likely to occur in the femoral model with osteoporosis or osteopenia; therefore, the selection of the internal fixation configurations in patients with osteoporosis is particularly important.
Bone-friendly lifestyle and the role of calcium or vitamin D supplementation
Published in Climacteric, 2022
Calcium is one of the important building blocks of bone, along with the other bone mineral phosphate, and with an adequate protein supply to allow the osteoblasts to construct and maintain the type I collagen matrix that is the critical structural and architectural component of bone. In the 1950s and 1960s, the idea was introduced that calcium intake was important in determining bone mass and, thus, fracture risk. These concerns were substantially based on calcium balance studies carried out over periods of a few weeks, but are not supported by more recent work in which bone balance over periods of years has been shown to be unrelated to calcium intake in populations with intakes greater than about 400 mg/day (Figure 2) [39]. These findings are consistent with the fact that calcium intakes in most of Africa and Asia were, until recently, <300 mg/day, yet these populations had fracture rates generally lower than those in Western Europe and North America. Calcium intake can become critical to bone health at lower levels, and some African children with intakes of about 100 mg/day but normal vitamin D status do develop impairment of bone mineralization.
Sex differences in bone mineral content and bone geometry accrual: a review of the Paediatric Bone Mineral Accural Study (1991–2017)
Published in Annals of Human Biology, 2021
Adam D. G. Baxter-Jones, Stefan A. Jackowski
Whilst peak bone mass is largely determined by heredity, which accounts for over 50% of the variance (Krall and Dawson-Hughes 1993), lifestyle patterns also influence bone mineral accrual. Nutrition is an important modifiable factor in the development and maintenance of bone mass (Vatanparast et al. 2007). Several investigators have found positive associations between dietary calcium intake and bone mineral status (Gunnes and Lehmann 1995). Sex differences have also been found in the magnitude of bone accrual with various food groups (Vatanparast et al. 2005) and between calcium intake and bone mineral content accrual (Carter et al. 2001). It is suggested that vigorous weight-bearing physical activity represents the best possibility for enhancing the attainment of an optimal level of bone mineral, within genetic limits (Seeman 2002). Bone responds to the mechanical stresses imposed by gravity and muscular contraction, pointing to the importance of mechanical loading as the prime modality in the preservation of skeletal integrity (Bailey and McCulloch 1990). The available evidence suggests significant and positive relationships between physical activity and lean mass and bone mineral accrual. However, it is also suggested that there are sex differences in physical activity levels during childhood, with higher levels observed in boys (Trost et al. 2002).