Serum Ferritin: Is It an Independent Predictor of Reduced Bone Mineral Density among Elderly Women?

Abstract

Aim: In vitro studies have shown that iron promotes osteoclast differentiation and bone-resorbing activity by enhancing mitochondrial biogenesis, whereas it suppresses osteoblastogenesis. In postmenopausal women, serum ferritin increases by 2-3 times due to the lack of a major mechanism of iron excretion, while menstrual blood decreases. Based on this observation, it has been hypothesized that in addition to estrogen deficiency, increased iron as a result of menopause could contribute to bone loss in postmenopausal women. So our aim was to investigate the association between serum ferritin levels and bone mineral density (BMD) in elderly women at various skeletal sites. Methods: Retrospective analysis of the medical records of 71 postmenopausal women having a mean age of (66 ± 7) years (range 60-83 years) was done. The collected data included age of menopause, past medical history, smoking habits, physical activity, and medication use. BMD was measured at the lumbar spine and femur by dual-energy X-ray absorptiometry, and other biochemical markers including, serum ferritin, 25 hydroxyvitamin D3, serum alkaline phosphatase, and parathyroid hormone were assayed. Results: We found that serum ferritin levels are significantly related to BMD of the total hip and lumbar vertebrae [with a p value of (0.01) and (<0.001) respectively] and T scores for the total hip, femur neck and lumber vertebrae [with a p value of (0.004), (0.036) and (<0.001) respectively] and their major determinants are age of menopause, menopause duration, weight, BMI and physical activity. Conclusion: This study suggests a positive association between serum ferritin levels and BMD in elderly women without hematologic disorders. Further study is warranted to verify the effects of iron on bone metabolism.