The Evaluation Of Bone In Chronic Kidney Disease-mineral And Bone Disorder Patients

Objective:Bone and mineral disorder is one of the most common clinical complications in patients with chronic kidney disease.Since Kidney Disease Improve Global Outcomes?KDIGO?issued Chronic Kidney Disease–Mineral and Bone Disorder?CKD–MBD?practice guideline in 2009,China has also published guidance for diagnosis and treatment of CKD-MBD.Because the research of CKD-MBD in China is only at the beginning stage and the medical communities update their cognition about CKD-MBD continuously.We still need more Chinese researches to develop our own clinical guideline.In this retrospective study,we aimed to analysis the prevalence and risk factors of low bone mineral density in CKD1⁵ patients.And we also designed to assess the ability of three widely used tools?bone mineral density?BMD?,osteoporosis self-assessment tool for Asians?OSTA?,and fracture risk assessment tool?FRAX??to discriminate fracture status in hemodialysis patients.Moreover,the microstructure of cancellous bone in hemodialysis is compared among three different bone turnover groups.Methods:?1?We selected CKD inpatients from December 2009 to December 2015and estimated glomerular filtration rate?GFR?using MDRD formula for Chinese.All patients were classified into 5 CKD stages according to K/DOQI guideline?2002?and were measured bone mineral density?BMD?at lumbar spine?L1-L4?femoral neck and total hip by dual energy X-ray absorptiometry?DXA?.Osteoporosis was defined by BMD according to the reference values suitable for Chinese population:osteoporosis?T?-2SD?;osteopenia?-2SD<T<-1SD?;normal?T?-1SD?.Clinical characteristics of all patients were also collected,including gender,age,BMI,biochemical parameters,smoking and alcohol taking,diabetes,medical history and fractures.The correlation between BMD and detection indexes was analysed and the independent risk factors for low bone mineral density in CKD patients were also explored.?2?We enrolled maintenance hemodialysis?MHD?patients in this study.BMD was tested using DXA at lumbar spine and hip region.OSTA was calculated from weight and age.FRAX score was obtained through the website.Clinical characteristics were also collected.All patients were divided into fracture group and non-fracture group.The independent risk factors for fractures among hemodialysis patients were analyzed.Discriminative abilities of BMD,OSTA and FRAX in fracture status were assessed with receiver operator characteristic curves analysis.?3?Bone biopsy was performed in MHD patients to obtain cancellous bone. Morphological parameters were measured by histomorphometry and Micro-CT.Bone biopsies were divided into three groups according to bone turnover status:high,low and mixed bone turnover.The differences of trabecular microstructure among the three groups were analyzed.And the correlation between two dimensional structure parameters measured by histomorphometry and three dimensional structure parameters by Micro-CT was studied in high bone turnover group.Results:?1?A total of 429 hemodialysis patients were enrolled in the study.Mean age of the00 hemodialysis patients?221 males and 208 females?was 53.89±16.14 years. Totally 43.59%?187 cases?of all patients were diagnosed as low BMD?including osteopenia 23.31%and osteoporosis 20.28%?.The number of patients in CKD1-5 was 127,72,75,39 and 116,respectively.And the prevalence of low BMD in CKD1-5 were 33.1%?41.7%?40%?38.5%?60.3%?including osteopenia 15.0%?22.2%?28%?12.8%?33.6%,respectively and osteoporosis 18.1%?19.4%?12.0%?25.6%?26.7%,respectively?.The differences of low BMD prevalence among the three groups were significant?P<0.05?. Simple linear regression analysis showed that BMD at femoral neck and total hip?g/cm²?were positively associated with BMI,eGFR,CO2-CP,Ca and 25?OH?D₃,but negatively associated with age,Scr,AKP,iPTH and P.No relationship was found between BMD at hip region?femoral neck or total hip?and UA.The BMD o f lumbar spine?L1-L4?were positively associated with BMI,and negatively associated with age,AKP.Multiple linear regression analysis showed that femoral neck BMD or total hip BMD was independently associated with Scr after adjusting potential confounding factors.Multiple logistic regression analysis revealed that serum creatinine was the independent risk factor for low BMD in CKD.?2?We included 136 hemodialysis patients in this study.Age of the patients?80 males and 56 females?was 59?47⁶6.75?years and duration of their dialysis was 55?26⁸6.75?months.There were total 16 fractures?11.76%?in those hemodialysis patients.BMD at any site?lumbar spine L1-L4,femoral neck and total hip?was independently associated with fracture by multiple logistic regression analysis.Areas under the curves of BMD?lumbar spine L1-L4,femoral neck,total hip?,OSTA,FRAX1?non-BMD model?and FRAX2?BMD model?were 0.669?95%CI,0.583 to 0.747,P=0.0234?,0.708?95%CI,0.624 to 0.783,P=0.0014?,0.736?95%CI,0.654 to 0.808,P=0.0003?,0.686?95%CI,0.601 to 0.763,P=0.0078?,0.715?95%CI,0.631 to 0.789,P=0.0004?,and 0.697 ?95%CI,0.613 to 0.773,P=0.0025?,respectively.The best cutoff were 0.973?0.719?0.859?0.2?3.3?2.8,respectively.The differences of their performance were not significant.?3?Nine cancellous bones were included in this study:3 in high turnover group,3 in low turnover group,and 3 in mixed turnover group.No difference of vBMD?BV/TV?Tb.N?Tb.Th?Tb.Sp?SMI and DA was found among the three groups.Bone histomorphometric measures of Tb.Ar and Tb.Wi did not correlate with Micro-CT measures of BV/TV and Tb.Th.Conclusions:The prevalence of low BMD was high in CKD patients.And the femoral neck BMD and total hip BMD decreased with the decline of renal function.Thus,we need to screen CKD patients for low BMD at early stage and continue to evaluate the specific risk factors.The mechanism by which uremic toxins effect bone metabolism will be investigated in the future study.In hemodialysis patients,all of the three risk assessment tools have the ability to discriminate fracture status.It's really important to find a Chinese suitable method to identify hemodialysis patients with high fracture risk as early as possible.Despite no difference of trabecular microstructure in three bone turnover status is found,the measure of Micro-CT enables us to analyze the spatial conformation of cancellous bone more precisely and covers the shortage of histomorphometry.It has also great significance for us to study the pathophysiology of renal osteodystrophy and evaluate the bone quality with the help of Micro-CT.