Background: Bone marrow (BM) adiposity is inversely related to bone mineral density and increases with ageing and menopause. We previously observed that the variation in BM fat fraction was more pronounced in premenopausal women compared to men and postmenopausal women. We hypothesized that the variation in BM fat fraction in premenopausal women is associated with hormonal variations during the menstrual cycle.
Objective: To investigate the dynamic changes in BM adiposity during the menstrual cycle.
Methods: In ten healthy premenopausal women, we measured vertebral BM adiposity using Dixons quantitative chemical shift imaging twice a week during one menstrual cycle. In addition, we measured serum concentrations of FSH, LH, progesterone, estradiol and the bone turnover markers C-terminal crosslinking telopeptides of collagen type I (CTx) and procollagen type I N propeptide (P1NP). The study was approved by the Medical Ethics Committee. Data were analyzed by a linear mixed model.
Results: The average change in fat fraction was 5.4% with an increase during the follicular phase (P=0.03) and a decrease during the luteal phase (P=0.09). Progesterone (P=0.03) and LH (P=0.03) had a significant overall association with the fat fraction. During the follicular phase, FSH (P=0.05, effect estimate per unit increase (EE) −0.36, 95% CI (−0.72 to 0.00) and LH (P=0.02, EE 0.3, 95% CI 0.05 to 0.57) were significantly associated with the fat fraction and during the luteal phase progesterone (P=0.01, EE −0.04, 95% CI −0.07 to 0.01), LH (P=0.03, EE 0.09, 95% CI 0.01 to 0.1) and CTx (P<0.01, EE 0.015, 95% CI 0.01 to 0.02) had a significant association.
Conclusion: This study indicates that the BM fat fraction is at least in part determined by the phase of the menstrual cycle, suggesting that BM fat is not merely the reciprocal of bone mineral density and can be regulated independently of bone mass.
17 May 2014 - 20 May 2014