Objective: To assess the relationship between body mass index (BMI) and basal LH and the LH-FSH ratio in normally menstruating women.
Design: Cross-sectional analysis.
Setting: A teaching hospital clinic.
Patient(s): Premenopausal women without cancer, not currently using oral contraceptives, selected from a familial ovarian cancer clinic or the general population.
Intervention(s): None.
Main outcome measure(s): Early follicular phase plasma LH and FSH.
Result(s): Luteinizing hormone increased slightly and nonsignificantly (P = 0.44) from the first to the second quintile of BMI and decreased over all subsequent quintiles. Women in the highest quintile of BMI (> 27.1) had significantly lower LH levels than women in the lowest quintile of BMI (< or = 20.4; P = 0.003). Compared with women in the second quintile of BMI who had the highest LH levels, women in the highest quintile of BMI had LH levels that were 40% lower. The relationship between BMI and the LH-FSH ratio was similar, though not as strong.
Conclusion(s): Over most of the range of BMIs observed in this study, BMI was inversely associated with LH. These results suggest that the upper limits of normal for LH may need to be shifted downward for heavier women.