Harvard Women's Health Watch

In the journals: Hormone therapy: Gallbladder risk is lower with a patch than a pill

In the journals

Hormone therapy: Gallbladder risk is lower with a patch than a pill

When women worry about taking postmenopausal hormone therapy (HT), they're usually thinking of the risks for breast cancer, stroke, and blood clots. A less familiar risk is gallbladder disease — inflammation of the gallbladder, usually caused by gallstones. It generally occurs more often in older women, but the risk is greater for those taking HT. In the Women's Health Initiative trials, estrogen alone or with a progestin raised the risk for gallbladder disease and gallbladder surgery by 60%. Although the risk goes up regardless of how HT is taken, a study published online in the medical journal BMJ (July 10, 2008), suggests that a transdermal gel or patch may be less risky than hormone pills.

These findings come from the United Kingdom's Million Women Study, a long-term investigation of the impact of hormone therapy and other factors on older women's health. Over a six-year period, researchers at the University of Oxford tracked the use of HT and the incidence of gallbladder disease and surgery to remove the gallbladder (cholecystectomy) among more than a million women in their 50s and 60s. (For more on the study, visit www.millionwomenstudy.org.)

About half the women in the study took HT, either currently (32%) or in the past (18%). Of those, 77% took oral estrogen and 18% transdermal estrogen (5% used an implant or other form). Compared with women who had never taken HT, current users were 64% more likely to develop gallbladder disease. Past users had a 27% higher risk, suggesting that estrogen use may cause a lasting change in the gallbladder. Among oral HT users, the risk of gallstones was greater with higher doses, and greater with equine estrogens (Premarin, or, when combined with a progestin, Prempro) than with estradiol. Adding a progestin to estrogen did not appear to affect the risk. The surprise came when researchers compared women taking oral HT with those using transdermal HT: the rate of hospital admissions for gallbladder disease or surgery was about 55% lower among women using the transdermal form.

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