Impact of high serum lipid levels and ectopic fat mass on bone density in obese and non-obese hyperlipidemic middle age women
Authors: Ashraf Elsayed Amer MD1, Alsaeed Elsayed Ahmed. A. Askar MD2, Hossam Ibrahim Abd El-Hamid MD3
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The aim of the study is to assess the relation between bone density and high serum lipid level status, to determine the contribution of fat mass to osteoporosis and the role of obesity associated with high fat content in osteoporosis. The study design was case control study. One hundred women of middle age ranged from (37 – 47 years) with normal menstrual cycle divided into two groups. Group Ι included 50 hyperlipidemic obese (HL-O) women and group Π included 50 hyperlipidemic non-obese (HL-NO) women of the same age. All these middle age women were suffering from hyperlipidemic disease with duration from 3 to 5 years, presented with rheumatological manifestations of hyperlipidemia, any symptoms of osteoporosis in the form of neck pain, low back pain, loss of height overtime, stopped posture and any debilitating pain of hips and wrists. Those with cardiovascular disease, diabetes, secondary osteoporosis caused by number of endocrine diseases, systemic diseases and who took drugs influence the bone metabolism and all other causes of osteoporosis were excluded from the study. Blood samples were taken to measure serum lipids Triglyceride (TG), Total Cholesterol (TC), High-Density Lipoprotein (HDL), and Low-Density Lipoprotein (LDL), bone biomarkers (bone alkaline phosphatase (BALP) and osteocalcin). Bone Mineral Density (BMD) at multiple skeletal sites was assessed by Dual-energy X-ray absorptiometry (DXA). Obesity was assessed by measuring body mass index (BMI) >30 kg/m2 with normal waist circumference is <88 cm, values were estimated according to WHO criteria. Also ectopic fat mass was assessed clinically. Partial correlation analysis was used to evaluate the relationships between mentioned measurements after adjustment for weight and age. Contribution of fat mass to bone density and the risk of osteoporosis was also assessed. After adjustment for age, weight, height, and BMI, the correlation between serum lipids and BMD was assessed. The effect of lipids on bone biomarkers was evaluated as well. We found a positive correlation between HDL and lumbar spine BMD. Furthermore, we did not find any significant effect of serum lipids on BALP. The results are interesting as the positive effect of serum lipids specially TG, low HDL and high LDL on long bone BMD (osteoporosis and osteopenia through mechanisms which are not merely mediated by pathways in which bone biomarkers' alterations are involved. TC and LDL were not related to BMD.
Keywords: Bone density, Hyperlipidemia, Middle aged, Menstrual women.