Hearing is less acute in postmenopausal women taking combined estrogen and progestin than in women taking no hormones or estrogen alone, according to a report published online Sept. 7 in the Proceedings of the National Academy of Sciences Early Edition.

Robert Frisina, PhD, of the University of Rochester Medical Center in Rochester, N.Y., and colleagues compared hearing abilities in 124 healthy postmenopausal women aged 60 to 86 who were taking estrogen and progestin (32), estrogen only (30), and who were not taking hormones (62).

The researchers found that pure-tone thresholds in both ears were poorer in women taking estrogen and progestin than in women on estrogen alone or not on hormones.

Women taking estrogen and progestin also had worse levels on distortion-producing otoacoustic emissions tests, and were also less able to discern speech amid background noise or quiet than women on estrogen alone or not on hormones.

"These findings suggest that the presence of progestin as a component of hormone replacement therapy results in poorer hearing abilities in aged women taking hormone replacement therapy, affecting both the peripheral (ear) and central (brain) auditory systems, and it interferes with the perception of speech in background noise," the authors write.

Guimaraes P, Frisina ST, Mapes F, et al. Progestin negatively affects hearing in aged women. Published online before print September 7, 2006, 