Background: Bone marrow fat is functionally distinct from subcutaneous and visceral fat depots. Bone marrow fat increases with ageing and menopause and is inversely related to bone mass. We previously observed a pronounced variation in bone marrow fat fraction during the menstrual cycle. We hypothesised that this variation is associated with changes in oestrogen levels. Our objective was to determine the effect of 17-β oestradiol administration on the vertebral bone marrow fat fraction.
Methods: We measured vertebral bone marrow fat fraction with MRI using Dixon Quantitative Chemical Shift Imaging (QCSI) every week for 6 consecutive weeks in 6 healthy postmenopausal women before, during and after two weeks of oral 17-β oestradiol administration (2 mg/day). In addition, we determined serum concentrations of bone turnover markers C-terminal crosslinking telopeptides of collagen type I (CTx) and procollagen type I N propeptide (P1NP). Data were analysed by linear mixed model.
Results: The vertebral bone marrow fat fraction decreased during two weeks of 17-β oestradiol administration (p<0.001) and increased after cessation. P1NP concentrations increased (p<0.05) and CTx concentrations decreased (p<0.001) during 17-β oestradiol administration.
Conclusion: We demonstrated that 17-β oestradiol administration rapidly decreases vertebral bone marrow fat fraction, suggesting that 17-β oestradiol affects bone marrow fat independent of bone mass.
Disclosure: The authors declared no competing interests. Peter H. Bisschop is supported by The Netherlands Organization for Health Research and Development (ZonMw) (grant number 90700308).