Physical and functional growth and development
Nick Draper, Helen Marshall in Exercise Physiology, 2014
Bone mineral density (BMD), often referred to simply as bone density, represents the bone mineral content relative to the outer bone area or volume, as mentioned above. The density of bone mineral is assessed by dual-energy X-ray absorptiometry (DXA) which reports an areal value (g · cm−2) for BMD. During the measurement of aBMD, a two-dimensional image of a three-dimensional structure is produced. As the depth of the bone remains unknown, a larger bone with a greater depth (as occurs with increasing age) will be reported as having a greater areal density as more photons emitted during densitometry will be attenuated by the greater mineral content of the larger bone. Volumetric BMD (g · cm−3), however, can be calculated from the areal value by taking bone dimensions into account. As the greater amount of mineral in a larger bone is dispersed in a larger bone volume, vBMD remains relatively unchanged with growth. It is clear that care must be taken when interpreting BMD data reported in the literature as aBMD and vBMD demonstrate differing responses to growth and development.
Menopause
David M. Luesley, Mark D. Kilby in Obstetrics & Gynaecology, 2016
Osteoporosis accounts for about 35 percent of bone fractures. Osteoporosis mainly affects the spine, hip, distal forearm and proximal humerus. In 2010, the calculated direct costs due to fractures were estimated to be €29 billion in the five largest EU countries - France, Germany, Italy, Spain and the UK.21–23 Dual energy X-ray absorptiometry (DXA) is the most inexpensive method of measuring bone density, involving low radiation exposure. Bone mineral density (BMD) is most often described as a T- or Z-score, both of which are units of standard deviation. The T-score describes the number of SDs by which the BMD in an individual differs from the mean value expected in young healthy individuals. Osteoporosis is based on the T-score for BMD assessed at the femoral neck and is defined as a value for BMD 2.5 SD or more below the young female adult mean (T-score less than or equal to -2.5 SD).24,25 The Z-score is mostly used in children and adolescents. A computer-based algorithm known as FRAX (www.shef.ac.uk/FRAX/) calculates the 10-year probability of a major fracture (hip, spine, humerus or wrist fracture). The variables used to calculate fracture risk are age, BMI and risk factors such as prior fragility fracture, family history, smoking, ever use of long-term oral glucocorticoids, rheumatoid arthritis, secondary causes of osteoporosis and alcohol consumption.
The minerals
Geoffrey P. Webb in Nutrition, 2019
Bone density can be measured in living subjects by techniques such as dual-energy X-ray absorptiometry. These bone density measurements are regarded as reliable indicators of bone strength. Although a sub-threshold density is a necessary permissive factor for osteoporotic fracture, bone mineral density measurements are imperfect predictors of individual susceptibility to fracture especially for fractures of the hip. Using bones from cadavers, Leichter et al. (1982) found high correlations between shear stress at fracture and both bone density and bone mineral content in the femoral neck. Breaking stress declined with age much faster than either bone density or bone mineral content suggesting that changes in bone strength are influenced by factors other than just bone density and mineral content e.g. changes in the micro-architecture of the bone.
The impact of musculoskeletal diseases on the presence of locomotive syndrome
Published in Modern Rheumatology, 2019
Manabu Akahane, Akie Maeyashiki, Yasuhito Tanaka, Tomoaki Imamura
Osteoporotic fractures are a significant health burden, as well as the major cause of morbidity in the elderly, and it is thus important to develop preventive strategies quickly. Although bone density is largely determined by heredity, a number of lifestyle-related factors play a role in the development or prevention of osteoporosis [13]. Bone mass increases through early life, childhood, and adolescence, and peaks in early adulthood. The magnitude of the peak bone mass achieved is a strong predictor of osteoporosis development later in life [14,15]. Therefore, the treatment of osteoporosis or measures for the prevention of osteoporosis includes changes in diet, exercise, and lifestyle, as well as medication [13,16]. Bisphosphonates such as alendronate and risedronate are the typical first-line medications used for patients with osteoporosis [17]. Our study indicated that osteoporosis had the strongest relationship with the presence of locomotive syndrome, apart from age; therefore, the treatment of osteoporosis through the use of medication or prevention through changes in lifestyle, including changes in exercise and diet, may be crucial and could be a modifiable determinant of locomotive syndrome. Hence, promoting the prevention and treatment of osteoporosis may reduce the proportion of those who require nursing care services.
Body composition and intake of nutrients associated with bone metabolism in young adolescents in a peri-urban setting
Published in South African Journal of Clinical Nutrition, 2019
M Fourie, GJ Gericke, MC Kruger
Adolescence, and the period prior to adolescence, is the critical period for bone accrual and the development of peak bone mass (PBM). It has been reported that 60% of the risk for osteoporosis can be explained by the amount of bone mineral laid down in the early years of life, and 60–90% of adult bone mass is acquired during the pubertal growth spurt.4 To ensure adequate bone mineral density (BMD) and bone mineral content (BMC), adequate dietary intake of key nutrients involved in bone metabolism such as calcium, phosphate, iron, zinc, selenium, magnesium, vitamin D and other key nutrients, as well as sufficient physical activity levels, is of the essence. Studies have investigated relationships between body weight, BMI, BMC and BMD. Many studies suggest that body weight is positively related to bone density. This protective effect could be related to the mechanostat theory. Bones react to mechanical stimuli (muscle and fat) by increasing osteogenesis.3–5
Treating exercise-associated low testosterone and its related symptoms
Published in The Physician and Sportsmedicine, 2018
David R. Hooper, Adam S. Tenforde, Anthony C. Hackney
Characteristics of bone health may include bone density and geometry, both measures of bone strength. BMD is most commonly used for clinical evaluation of bone health using DXA. DXA obtains measures of bone density using two-dimensional areal BMD values [46]. The International Society of Clinical Densitometry recommends indications for dual energy x-ray absorptiometry (DXA) to measure BMD for screening in men greater than 70 years of age, or men under 70 years of age with one or more risk factor including low body weight, prior fracture, high-risk medication use, or a disease associated with bone loss [47]. In the case of individuals exhibiting EHMC, due to concerns that reduced testosterone is associated with low BMD [20], screening DXA may be considered to evaluate bone health. Clinical assessment includes total body less head and lumbar spine for individuals less than 18 years of age and lumbar spine and femur values in men ages 18 and older [48]. BMD and bone mineral content (BMC) values are standardized to Z-scores in younger males using reference values based on age, sex, and ethnicity.
Related Knowledge Centers
- Bone
- Bone Mineral
- Density
- Lumbar Vertebrae
- Osteoporosis
- Medical Imaging
- Radiology
- Nuclear Medicine
- Hospital
- Hip