Objective: To explore the bone turnover marker profile during the menstrual cycle of premenopausal women.
Design: This was a noninterventional study. Levels of bone turnover markers, including serum C-terminal telopeptide of type I collagen (sCTX), bone-specific alkaline phosphatase, osteocalcin, procollagen type 1 N propeptide, and urinary N-terminal telopeptide of type I collagen, were measured in blood and urine samples during one menstrual cycle. Levels were expressed as raw test results and percent change from serum luteinizing hormone peak. Differences in mean levels of bone turnover markers between menstrual phases and subphases were examined.
Results: Fifty-five women comprised the per-protocol population. Mean sCTX values were 0.48 ng/mL during the follicular phase (FP), 0.47 ng/mL at serum luteinizing hormone peak, and 0.43 ng/mL during the luteal phase (LP). Additionally, the mean percent change from luteinizing hormone peak varied from +4.35% during the FP to -5.11% during the LP (P = 0.0014). Mean sCTX levels during the early and through mid FP were significantly higher than levels during the mid and late LP. The pattern for urinary N-terminal telopeptide of type I collagen was similar to that of sCTX but not statistically significant. There was a statistically significant tendency for procollagen type I N propeptide levels to be lower during the FP relative to the LP. Levels of osteocalcin and bone-specific alkaline phosphatase did not vary significantly during the menstrual cycle.
Conclusions: Levels of some bone turnover markers varied during the menstrual cycle. A statistically significant change in sCTX (9.46%) occurred between the FP and LP of the menstrual cycle.