Relationship Between Lipid Metabolism And Bone Metabolism In Peking Postmenopausal Women

Background:Osteoporosis is a common disease that affects the quality of life of postmenopausal women.The main cause of postmenopausal osteoporosis is an increase in bone turnover.Bone resorption is greater than bone formation,resulting in decreased bone density,destruction of bone microstructure,increased skeletal fragility,and prone to fracture.The prevalence of hyperlipidemia and coronary heart disease in postmenopausal women are also significantly increased.Abnormal lipid metabolism and changes in bone metabolism often occur simultaneously in postmenopausal women,and studies have shown that the occurrence of vertebral fractures in postmenopausal women is closely related to atherosclerosis.Therefore,it is necessary to explore the relationship between lipid metabolism and bone metabolism in postmenopausal women.Objective:To study the relationship between lipid metabolism and bone density,osteoporotic fractures and bone turnover in postmenopausal women in Beijing.Subjects and methods:1.Subjects:A total of 2,260 postmenopausal women participated in the 2013PK-VF study in Beijing.1,155 were eventually included in the study according to inclusion and exclusion criteria.Among them,607 people participated in the 2008 PK-VF study and were selected for the longitudinal cohort study.2.Methods:(1)Basic information:The use of questionnaires to collect basic information,menstruation and childbirth,lifestyle,activity,history of comorbidities,medication history,fracture-related history,and general health status assessment.(2)Serum biochemical markers:Blood was drawn intravenously,and serum was collected by centrifugation.Determination of routine biochemical indicators(ALT,Cr,P,Ca,and Glu),biochemical markers of bone metabolism(Bone turnover markers including?-CTX,P1NP,OCN and ALP,calmodulin including 25OHD and PTH),biochemical markers of lipid metabolism(TG,TC,HDL-C,LDL-C,Lp(a),ApoA and ApoB)and other biochemical markers(hsCRP,GA and Alb).(3)Bone mineral density:The values of LS BMD,FN BMD and TH BMD were measured using DXA and converted to T values.(4)Lateral X-ray image of the thoracolumbar vertebrae:Digital X-ray machines were used to record the lateral images of the thoracic and lumber vertebras to evaluate the presence of vertebral fractures.The Genant semi-quantitative method of vertebral fractures was used to determine fracture grading.(5)Statistical methods:Comparison between groups,correlation analysis,and regression model were constructed.Confounding factors were adjusted.Results:1.The median age of the sample population was 64 years and the median postmenopause time was 13 years.The average BMI was 25.31 kg/m~2.The average T values of bone mineral density at the lumbar spine,femoral neck,and total hip were-1.27,-1.20,and-0.67 respectively.295(25.90%)people had osteoporosis.In the total sample,347(30.04%)had osteoporotic fractures,and the number of confirmed vertebral fractures by lateral X-ray images was 250(21.65%).The levels of serum?-CTX in 403(35.4%)people were higher than the upper limit of normal.The median value of osteocalcin was 17.98 ng/mL and the median value of P1NP was 53.34 ng/mL.39(3.46%)people had serum 25OHD levels above 30 ng/mL,and 56(4.93%)people had serum PTH levels above the upper limit of the reference range.In terms of serum lipids,132(11.43%)people had serum TC?6.2mmol/L,163(14.11%)had serum HDL-C<1.0 mmol/L,90(7.79%)had serum LDL-C?4.1 mmol/L.and 150(12.99%)had serum TG levels?2.3 mmol/L.2.Relationship between lipid metabolism and bone density:By constructing a linear regression model and adjusting confounding factors,serum HDL-C levels were negatively correlated to FN BMD.FN BMD decreased by 0.028g/cm~2 for 1mmol/L of increase in HDL-C(?=-0.028,p=0.020).Serum TG,on the other hand,had a positive relationship with FN BMD and TH BMD.TG increased 1mmol/L followed by FN BMD increase of 0.009g/cm~2(?=0.009,p=0.014)and TH BMD rise of 0.014 g/cm~2(?=0.014,p=0.013).Serum HDL-C levels were negatively related to bone mass change rate(p=0.021),while ApoA/ApoB ratios were negatively correlated with bone mass change rate(p=0.004).3.Relationship between lipid metabolism and bone turnover levels:The results of constructing linear regression models showed that the levels of serum TC,HDL-C,LDL-C,ApoA and ApoB were all significantly positively correlated to osteogenic markers OCN(p<0.02)and P1NP(p<0.05).Lipid profiles had no relationship with?-CTX.4.The relationship between lipid metabolism and osteoporotic fractures:The correlation between lipid levels and existing or new vertebral fractures was not found after univariate general linear models corrected for confounding variables.The HDL-C/LDL-C ratio was a risk factor for the development of overall osteoporotic fractures(OR:2.62,95%CI:1.13-6.11).Conclusion:The results showed that serum TG levels were positively correlated with FN BMD and TH BMD in Peking postmenopausal women,while serum HDL-C levels were negatively associated with FN BMD.The HDL-C/LDL-C ratios were risk factors for overall fragility fractures.Serum TC,HDL-C,LDL-C,ApoA and ApoB levels were all positively correlated with bone formation markers P1NP and OCN.This suggested that in postmenopausal women,lipid metabolism may be associated with the onset of osteoporosis.