Women taking the most common form of hormone replacement therapy (HRT) may experience 10% to 30% more hearing loss, compared with similar women not taking HRT, according to a recent study published by the Proceedings of the National Academy of Sciences. Researchers suggested that HRT that included progestin, the synthetic form of the hormone progesterone, possibly accelerated normal age-related hearing loss. The study included 124 women taking progestin and showed that they had the hearing of women 5 to 10 years older. The study team consisting of scientists, nurses, and audiologists tested the hearing of 124 healthy women between the ages of 60 and 86. The women were divided into 3 groups: those who had taken HRT that included only estrogen, those who had taken both estrogen and progestin, and those who had never been on HRT. All the women were tested with a standard "pure tone" test to measure which frequencies they could hear, as well as with more advanced tests to determine how healthy the ears were and how the brain deciphers the signals received from the ears. In all measures, women whose HRT included progestin had worse hearing than the other groups, showing problems not only in the inner ear, but in the portions of the brain used for hearing. Researchers had anticipated that the estrogen group would actually show improved hearing, but that was not the case. Senior author Robert D. Frisina, PhD, said, "In light of these findings, we feel that hearing loss should be added to the list of negative things to keep in mind when talking about HRT." Further studies are under way to determine how progestin affects the ears and brain.

Ms. Farley is a freelance medical writer based in Wakefield, RI.