Analysis Of Bone Mineral Density And Body Composition At Different Parts In People At Different Ages

Objective: Osteoporosis (OP) is a kind of whole body bone disease characterized by bone loss and bone micro-structure destroy, which lead to increased bone fragile and high risk of fracture. OP may happen in population in any gender and ages, but more in post-menopausal women and aging men. The severe consequence of OP is the bone fracture, which increases rate of deformity and mortality. With the process of aging in our population, the incidence of OP is also increasing. Therefore, early OP diagnosis and treatment to prevent bone fracture and reduce disability, has become a major concern in our social life. For the pathogenesis of osteoporosis, both at home and abroad had done a great deal of research, though some had shown that there were closely relations between the bone mass and body composition such as muscle and fat ,how they impact on the bone mass in different age people of different gender is not very clear.Bone density measured by dual-energy X-ray absorptiometry (DEXA) is the golden standard for OP diagnosis, which can also be usded for body composition measurement.This study aim to establish the databases of bone mineral density of population at ages by measuring bone mineral density and body composition at different parts of the body, analysising the correlation between body composition and BMD and the incidence of osteoporosis.Methods: A total of 493 subjects were included. All subjects were aged from 20-80 years old and every 10 years were considered into one group. male subjects were 225 : there were 28 subjects at age of 20-29, 35 at age between 30-39 year-old, 40 at age of 40-49, 42 at age of 50-59 , 39 at 60-69 year-old and 41 at age of 70-79. There were total 268 female were included: there were 36 at age between 20-29, 43 at age between 30-39 , 45 at age between 40-49, 51 at age between 50-59, 48 at age between 60-69, and 45 at age between 70-79. All subjects were measured BMD at L2-L4 lumbar vertebrae, femur (neck, ward triangle, trochanter, InterTro and total) and whole body lean and fat mass by DEXA (dual energy X-ray absorptiometry). Menopause years were also recoded in female subjects.Results:1 Results of regression analysis1.1 Results of linear correlation analysis.In Male: L2-L4,total hip BMD were positively correlated with BMI and the corresponding trunk lean mass(TKLM),leg lean mass (LLM)and total lean mass(TLM), but were negatively correlated with age. There was no significant correlation between BMD and corresponding fat mass.In Female: L2-L4,total hip BMD were positively correlated with BMI and the corresponding trunk lean mass(TKLM),leg lean mass (LLM)and total lean mass(TLM), yet, were also positively correlated with the corresponding trunk fat mass(TKFM),leg fat mass (LFM)and total fat mass(TFM),. L2-L4,total hip BMD were negatively correlated with the age and MPY.1.2 Results of multiple regression analysis.Data from standard regression coefficient (Bata) have indicated that, L2-L4, the mean femoral BMD in male were closely related with age, BMI and the corresponding lean mass, but not fat mass; In female, L2-L4 and the mean femoral BMD were closely related with age, BMI, MPY, the corresponding lean mass and fat mass.2 The comparison of clinical characteristics in different groups2.1 comparisons of male subjects at different age groups: there was no difference found in BMI among all age groups. BMD of different parts were gradually reduced with aging, in which, BMD were highest in all measured parts in 30-39 age group, and especially higher in lumbar 2-4, femoral neck and ward triangle than other age groups(p<0.05). There were no statistical differences found in BMD of different parts between 20-29, 40-49, 50-59 age groups (p>0.05), BMD of L2-4, femoral neck and trochanter in were significantly higher 60-69 age group than the 70-79 group(p<0.05) . The lean mass of different parts were gradually reduced with aging, TKLM,LLM,TLM in 30-39 age group were all significantly higher than other age group(p<0.05), except 40-49 age group (p>0.05). TKLM,TLM in 50-59 age group were significantly higher than those the 70-79 group(p<0.05). The fat mass of different parts had a trend to increase with aging, but only TKFM,LFM,TFM in 70-79 age group were significantly higher than those of 20-29 and 30-39 age groups(all p<0.05). No statistical differences were found between other age groups (all p>0.05).2.2 Comparison of female subjects at different age groups: there were no differences found in BMI in all age groups. BMD of different parts were gradually reduced with aging. BMD of different parts in 30-39 age group were the highest in all age groups, but not so significant in BMD of L2-4,NT and ward triangle when compared with 20-29 and 40-49 age groups (p>0.05) . there were significant differences in BMD of NT, ward triangle and GT between 40-49 and 50-59, 60-69 and 70-79 age groups (p>0.05). The lean mass of different parts were gradually reduced with aging, TKLM,LLM,TLM in 30-39 age group were higher than other age groups(p<0.05), in addition, TKLM,LLM,TLM in 40-49 age group were significantly higher than 60-69 and 70-79 age groups(p<0.05). The fat mass of different parts was gradually increased with aging. TKFM,LFM,TFM in 60-69 age group were higher than 20-29, 30-39, 40-49 age group separately (p<0.05). The fat mass of different parts in 70-79 age group were higher than 50-59 group (p<0.05).3 The incidence of osteoporosisAccording to WHO diagnostic criteria for osteoporosis, the incidences of osteoporosis in male age groups were: 40-49 age group 5%,50-59 age group 13.04%, 60-69 age group 24.39%, 70-79 age group 41.86%. In female age groups were: 40-49 age group 7.5%,50-59 age group 26.39%, 60-69 age group 46.34%, 70-79 age group 67.44%.Conclusions:1 The peak bone masses were at 30-39 age groups in both male and female. BMD of different parts were gradually reduced with aging, and, the losing rate in female seemed faster than male, especially in the women at the 5-10 years of postmenopausal.2 BMD was significantly associated with the lean mass of different parts in male, but not fat mass. In female, the lean mass and fat mass of different parts were all significantly associated with BMD.3 We have established the database of BMD and the body composition of different parts in all age's groups. Sample size is still increasing and , these data will provide the basis for OP prevention and risk assessment.