Correlation between femoral head bone iron content, serum ferritin and bone mineral density of postmenopausal women with femoral neck fragility fracture

Abstract

Objective To explore the correlation between femoral head bone iron content,serum ferritin (SF) and bone mineral density of postmenopausal women with femoral neck fragility fracture.Methods From June 2010 to March 2013,156 postmenopausal women with femoral neck fragility fractures aged from 56 to 92 years old,with an average age of 72.40±8.97 years,were divided into 5 groups based upon the stratification of 10-year age intervals (≤60,61-70,71-80,81-90 and ≥91).Blood samples were collected to determine iron metabolism and bone metabolic markers after overnight fasting.Bone specimens were obtained for detecting bone iron contents and performing iron stain respectively after hip arthroplasty surgery.BMD was measured by dual energy X-ray absorptiometry(DXA)at hip and lumbar spine from L1 to L4 ten days after surgery.Results There were significant differences in the values of bone iron content,SF,transferrin,total iron binding capacity,serum procollagen type Ⅰ N-terminal propeptide,β-carboxy terminal telopeptide of collagen type Ⅰ and BMD at hip and L1 to L4 in all groups.BMD at hip and L1 to L4 decreased while bone iron content and SF increased with age; the peaks of bone iron content and SF were both in 81-90 years group; the average of bone iron content and SF was 96.81 μg/g and 235.66 μg/L respectively.There were 100 patients (100/156,64.1％) whose SF was over 200 μg/L.Bone iron content combined with SF,age and BMI could be put into the regression models of BMD at various proximal femur sites (femoral neck R2=0.443,Wards triangle R2=0.397,greater trochanter R2=0.322 and total femur R2=0.379).After adjustment of age,weight,BMI and other factors,we found that bone iron content and SF were negatively correlated with BMD at proximal femur,but had no significant correlation with BMD at lumbar spine.Conclusion Iron accumulation is prevalent in postmenopausal women with hip fragility fractures.High bone iron content and SF are independent risk factors for low BMD at proximal femur.These results provide clinical evidences that iron accumulation is associated with postmenopausal osteoporosis. Key words: Osteoporosis, postmenopausal; Femur head; Ferritins; Bone density