Correlation Between Organ Iron Overload And Bone Mineral Density And The Effect Of Iron Overload On Lumbar Spine Bone Mineral Density Measured By DXA

Objective:To explore the correlation between T2*values of hepatic and pancreatic iron overload and bone mineral density(BMD)of lumbar and hip and the effect of organ iron overload on lumbar spine BMD measured by dual-energy X-ray absorptiometry(DXA),for further understanding the correlation between iron overload and BMD and the feasibility of DXA in evaluating osteoporosis in patients with iron overload.Materials and methods:34 patients with confirmed diagnosis of iron overload in Peking Union Medical College Hospital from March 2014 to May 2019 were selected.T2*values of liver and pancreas were calculated by multi-echo fast gradient-echo sequence and BMD of lumbar and hip were measured by DXA.All patients were categorized into no-mild iron overload group(hepatic T2*value≥ 3.8ms and pancreatic T2*value≥ 21ms)and moderate-severe iron overload group(hepatic T2*value<3.8ms and/or pancreatic T2*value<21ms)based on hepatic and pancreatic T2*values and were stratified into normal BMD(T-score≥-1)and abnormal BMD group(T-score<-1)based on the lower T-score of lumbar vertebrae or femoral neck,respectively.Statistical analysis was performed with t test,chi-square test,Spearman correlation analysis and ROC curve.Results:Patients with abnormal BMD(n=13)had significantly lower T2*values in liver and pancreas than those with normal BMD(n=21)(p<0.05).Liver T2*values were significantly and positively correlated with BMD and T-scores of L1-4 and L2-4(r=0.362-0.385,P<0.05).Pancreatic T2*values were significantly and positively correlated with BMD and T-scores of L2-4,femoral neck and total hip(r=0.397-0.473,P<0.05).An optimal threshold of Liver T2*value=4 ms was determined for predicting abnormal BMD with a sensitivity of 80.0%and a specificity of 69.2%.A cutoff value for LLR of 34.15ms yielded a sensitivity of 75.0%and a specificity of 100%.of which there were significant differences in BMD of L2-4 and L3-4 and T-scores of L1-4,L2-4,L3-4(p<0.05)and there were no significant differences in BMD of L1-4(P>0.05).Among patients with moderate-severe iron overload(n=16),the T-score of L1-4 was significantly higher than that of L2-4(p<0.05),whereas there were no significant differences between BMD of L1-4 and L2-4(P>0.05).Among patients with no-mild iron overload group(n=18),the BMD and T-score of L1-4 was significantly lower than that of L2-4(p<0.05).Conclusion:Hepatic and pancreatic iron overload are closely related to BMD of lumbar and hip,providing guidance for clinical prevention of osteoporosis and objective basis for treatment of osteoporosis in patients with iron overload.In addition,hepatic and pancreatic iron overload can lead to higher BMD and T-score of L1-4 measured by DXA than the actual values,which is not conducive to early reflect the decrease in BMD of lumbar spine and early diagnosis of osteoporosis.