C-reactive protein across the menstrual cycle.

Area of Science:

• Reproductive Endocrinology
• Inflammation Biomarkers
• Women's Health Research

Background:

• C-reactive protein (CRP) is a sensitive inflammation biomarker.
• Conflicting data exist on estrogen and progesterone effects on CRP in women.
• Exogenous hormone use suggests estrogen increases CRP, progesterone decreases it.
• Endogenous hormone effects in normally cycling women appear opposite.

Purpose of the Study:

• To evaluate associations between menstrual cycle hormone changes and CRP.
• To examine relationships between menstrual events (menses, ovulation) and CRP.

Main Methods:

• Eight female subjects provided samples across eleven menstrual cycles.
• Blood samples were analyzed for CRP.
• Urine samples were analyzed for beta-follicle stimulating hormone (betaFSH), pregnanediol 3-glucuronide (PDG), and estrone glucuronide (E1G).
• Ovulation day estimated via hormone levels; menses presence/absence reported.
• Random-effects linear regression used for analysis.

Main Results:

• A ten-fold increase in progesterone correlated with a 23% increase in CRP (P=0.01).
• A ten-fold increase in estrogen correlated with a 29% decrease in CRP (P=0.05).
• Menses showed a non-significant 17% increase in CRP (P=0.18).
• No significant association found between ovulation, FSH, and CRP.

Conclusions:

• Endogenous progesterone positively associates with CRP, while estrogen negatively associates.
• Menstrual cycle hormone fluctuations significantly impact CRP levels.
• Future inflammation studies in reproductive-age women must control for menstrual cycle phase.