Objective: Human chorionic gonadotropin (hCG) has proliferative effects on uterine smooth muscle and leiomyoma tissue in vitro. We hypothesized that luteinizing hormone (LH) would have the same effect by activating the LH/hCG receptor, and it would follow that premenopausal women with higher basal LH levels would be more likely to have leiomyomata.
Methods: Randomly selected women, aged 35 to 49 years, from a prepaid health plan were screened for leiomyomata with pelvic ultrasound. Urine samples collected during the first or last 5 days of the menstrual cycle were analyzed for LH by immunofluorometric assay, and concentrations were corrected for creatinine (n = 523). Logistic regression and Bayes analyses were used to evaluate the association of LH with presence and size of leiomyomata, adjusting for age, and other risk factors.
Results: Women with higher LH were more likely to have leiomyomata (adjusted odds ratios for second and third tertiles were 1.7 and 2.0 compared with lower tertile; 95% confidence intervals, 1.0 to 2.7 and 1.2 to 3.4, respectively). The association was stronger for large leiomyomata. Bayes analyses designed to estimate LH effects on tumor onset separately from tumor growth showed significantly accelerated tumor onset but little evidence of effects on tumor growth. Age, an independent risk factor for leiomyomata, was not affected by inclusion of LH in the logistic models.
Conclusions: As hypothesized, women with higher LH were more likely to have leiomyomata, but this did not explain the age-related increase in leiomyomata during perimenopausal ages. Determining whether LH is causal or a marker for susceptibility will require further research.