CAN BODY MASS INDEX AND BONE MINERAL DENSITY PREDICT OSTEOPOROSIS A DEXA SCAN BASED STUDY

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1 International Journal of Advances in Health Sciences (IJHS) ISSN Vol2, Issue4, 2015, pp Research Article CAN BODY MASS INDEX AND BONE MINERAL DENSITY PREDICT OSTEOPOROSIS A DEXA SCAN BASED STUDY R. B. Uppin and Srinath M Gupta KLE University s JN Medical College and Dr. PrabhakarKore Hospital & MRC, Belagavi , Karnataka, India. [Received-22/07/2015, Accepted-30/07/2015, Published- 21/08/2015] INTRODUCTION Normal aging is associated with a high incidence of osteoporosis and bone marrow adiposity. (1) Bone remodeling and adiposity are both regulated through the hypothalamus and sympathetic nervous system. Adipocytes (cells for storing energy) and osteoblasts (bone forming cells) derive from a common progenitor, the mesenchymal stem cell. This has been well accepted that the most powerful measurable determinant of fracture risk is the amount of bone in the skeleton as measured by Bone Mass Density. Extensive data have shown that high body weight or BMI is correlated with high BMD and that a decrease in body weight leads to bone loss. (2,3) An extensive literature has been developed exploring the clinical, epidemiologic and pathophysiologic linkage between obesity and osteoporosis. The purpose of this study is to review our current understanding of this relatively new area of investigative research. MATERIAL AND METHODS DEXA SCAN studies were done for 500 patients of all age groups over 25 years from Jan 2010 to Jan 2015 attending KLE University s Dr. Prabhakar Kore Hospital and Medical Research Centre. BMI (kg/m 2 ) was calculated as weight (kg) divided by height square (m 2 ). (4) We divided 500 patients who were studied via DEXA scan, into normal weight (18.5 < BMI, 25.0 kg/m), over-weight (25.0 < BMI,30.0 kg/m), and obese (BMI > 30.0kg/m) The T-score is a widely used parameter to assist in the interpretation of BMD results.it measures the departure of the patient s BMD value from the mean BMD for a young adult healthy population in units of the population standard deviation (SD). (5) The Z-score is similar in concept to the T- score, with the exception that the mean BMD

2 and SD for a healthy age- and sex-matched population are used as reference values instead of the mean BMD and SD for a young normal group. Z-scores are not used to define osteoporosis, since they would not reflect the increasing prevalence of osteoporosis with age. For example, elderly patients may have a Z- score of zero, based on comparison to their own age group, but a T-score that would put them in the osteoporotic category Normal BMD value within 1 S.D. of youngadult mean (T-score at or above -1) Osteopenia BMD value between -1 S.D. and S.D. below young-adult mean (T-score between -1 and -2.5) Osteoporosis BMD value at least -2.5 S.D. below young adult mean (T-score at or below -2.5) BMD of the hip can be measured at several regions, including the femoral neck, trochanteric, intertrochanteric, Ward s Triangle and/or total hip. Unlike the spine, where cancellous bone is uniformly distributed and, thus, shows a uniform pattern of bone loss, the hip shows variable BMD because different areas of the femur are composed of different percentages of cancellous bone, and have different risks of fracture. R. B. Uppin and Srinath M Gupta 495

3 RESULTS Distribution of gender showed that 87.1% were females and the remaining were males. The sex ratio was found to be male : female = The respondents were classified in to three broad age groups, years, years, and 60 years and above. No. % No. % No. % Total Normal BMI overweight obese Age Total : 6.7. Age ranged from 25 to 80 years. The mean and standard deviation of age was 50.5 ± 11.5 years. The BMD was found to be significantly higher in obese and severely obese patients as compared to the BMD of normal weight category. R. B. Uppin and Srinath M Gupta 496

4 But the mean BMD values of obese and severely obese groups did not differ significantly. A significant negative correlation between age and BMI in the normal weight and obese patients was observed while in the severely obese group age did not correlate with the BMI significantly. Age and BMD correlated negatively with each other in all the groups and the correlation was significant which suggests that advancing age is associated with low BMD DISCUSSION Osteoporosis is another major public health problem, characterized by excessive skeletal fragility and susceptibility to low-trauma fracture among the elderly. This excessive skeletal fragility is attributable to intrinsic skeletal factors such as low bone mass, unfavorable geometry at cortical bone sites, poor bone structure at cancellous bone sites, and sluggish or ineffective repair of microdamage. Both diseases are affected by genetic and environmental factors. Studies of adipocyte function have revealed that adipose tissue is not just an inert organ for energy storage. These molecules affect human energy homeostasis and may be involved in bone metabolism, which may contribute to the complex relationship between fat mass and bone.the Studies of National Osteoporosis Foundation and others suggested that low BMI should be included in the risk assessment tools for evaluation of osteoporosis and osteoporotic fracture risk. (6-7) Recently, bone has been considered an endocrine organ affecting body weight control and glucose homoeostasis through the actions of bone-derived factors such as osteocalcin and osteopontin. (8) The putative crosstalk between fat and the skeleton constitutes a homoeostatic feedback system in which adipokines and molecules secreted by osteoblasts and osteoclasts represent the link of an active bone-adipose axis. (9) It has been well accepted that the most powerful, measurable determinant of fracture risk is the amount of bone in the skeleton, as measured by either BMD Extensive data have shown that high body weight or BMI is correlated with high BMD and that a decrease in body weight leads to bone loss.obesity is also associated with BMD because of the conversion of androgen to estrogen, which improves bone mass in both men and women and maintains healthy plasma levels of insulin and regulating factors including insulin-like growth factor-1, leptin, and adiponectin. (10) These correlations are seen in both men and women, across the entire adult age range, and throughout the skeleton. Several potential mechanisms have been proposed to explain the complex relationship between fat and bone mass. One straightforward explanation is that greater fat mass imposes a greater mechanical stress on bone, and in response, bone mass increases to accommodate the greater load.several lines of evidence from environmental factors and medical interventions also support an inverse correlation between fat mass and bone mass. For instance, physical exercise increases bone mass while reducing fat mass. Menopause has also been associated with increased bone loss, increased fat mass, and decreased lean mass. CONCLUSION This study is an attempt to address one of the important public health problems, which can be controlled if preventive measures are taken at an early stage. R. B. Uppin and Srinath M Gupta 497

5 MESENCHYMAL STEM CELLS GIVING RISE TO OSTEOBLAST AND ADIPOCYTES More about the risk factors could not be investigated, as this is a retrospective case record analysis. The results of this study suggest that advancing age and lower BMI are important risk factors for the occurrence of low BMD and thus leading to osteoporosis. Further studies are required to investigate the effect of other factors like exposure to sunlight, calcium intake, and other habits like smoking, diet, and so forth. REFERENCES: 1. Rossener S. Obesity: the disease of the twenty-first century. International Journal of Obesity and Related Metabolic Disorders. 2002;26:S2 S4. [PubMed] 2. Cummings SR, Nevitt MC, Browner WS, et al. Risk factors for hip fracture in white women. The New England Journal of Medicine. 1995;332(12): [PubMed] 3. Ravn P, Cizza G, Bjarnason NH, et al. Low body mass index is an important risk factor for low bone mass and increased bone loss in early postmenopausal women. Journal of Bone and Mineral Research.1999;14(9): [PubMed] R. B. Uppin and Srinath M Gupta 498

6 4. WHO/IASO/IOTF. The Asian-pacific perspective: redefining obesity and its treatment World Health Organization Geneva, Switzerland: World Health organization; Assessment of fracture risk and its application to screening for postmenopausal osteoporosis. [PubMed] 6. National Osteoporosis Foundation. Osteoporosis. Physician's Guide to Prevention and Treatment of Osteoporosis. Washington, DC, USA: National Osteoporosis Foundation; Black DM, Steinbuch M, Palermo L, et al. An assessment tool for predicting fracture risk in postmenopausal women. Osteoporosis International. 2001;12(7): [PubMed] 8. Gomez-Ambrosi J, Rodriguez A, Catalan V, Fruhbeck G. The boneadipose axis in obesity and weight loss. Obesity Surgery. 2008;18: [PubMed] Takeda S. Effect of obesity on bone metabolism. Clinical Calcium. 2008;18(5): [PubMed] 10. Thomas T, Burguera B, Melton LJ, III, et al. Role of serum leptin, insulin, and estrogen levels as potential mediators of the relationship between fat mass and bone mineral density in men versus women.bone. 2001;29(2): [PubMed] R. B. Uppin and Srinath M Gupta 499

Osteoporosis has been identified by the US Surgeon General

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