While the scientists' results -- reported in the Proceedings of the National Academy of Sciences -- established no definitive link between HRT and hearing loss, they theorized progestogen might alter the levels of the acid GABA, found in the brainstem and auditory system.
Many middle-aged women undergo HRT to help deal with the mood swings, hot flashes and other menopausal symptoms, but the procedure has come under fire in recent years because of its links to heart problems and dementia. Estrogen-only HRT increases womb cancer risk, so it is usually only given to women who have had hysterectomies, but other studies have suggested that both estrogen-only and estrogen and progestogen HRT may increase the risk of breast cancer.
David Sturdee of the Royal College of Obstetricians and Gynaecology disagreed that the situation was that dire, noting the link to hearing loss was "far from established."
"There may be slight risks, but if the symptoms of menopause are severe each individual has to ask themselves if they would be better being off HRT."
The researchers recommend that HRT medications undergo more rigorous testing to make sure they do not negatively affect sensory perception.
"Sensory declines in elderly women can significantly interfere with communication abilities, including speech and hearing, professional and economic productivity, family relations and quality of life," said lead researcher Robert Frisina. "Therefore increased and improved sensory testing in drug and medication development for our elderly population is warranted."