Breast electrical impedance and estrogen use in postmenopausal women.
OBJECTIVES: To examine the potential for using electrical impedance measurements on the breast as an indicator of estrogen activity in breast tissue. METHODS: Eighty-six postmenopausal women were examined with TS2000, a device that measures electrical capacitance and conductance on the breast. Seventy women had undergone natural menopause (NM) and 16 had had a hysterectomy/ovarectomy. Twenty-one women were using estrogen replacement therapy (ERT). Each woman had electrical impedance measured over several frequencies on the nipple sector of both breasts. We analyzed capacitance and conductance at 200 and 1100 Hz and the slopes and intercepts of regression lines relating capacitance and conductance to the natural log of frequency. RESULTS: Type of menopause (natural or induced) was not statistically related to any measured variable. The number of years since the start of menopause was statistically related to all measured variables. Overall, levels of capacitance and conductance decreased as the number of years since the start of menopause increased. Women who used ERT had a statistically higher level of nipple conductance at 200 Hz than did women who did not use ERT. CONCLUSIONS: The pattern of electrical measurements on the nipple (and in particular conductance at 200 Hz) is correlated with the pattern of estrogen changes after menopause. These data indicate that electrical measurements might be a useful, non-invasive assay of estrogen activity in breast tissue.