Postmenopausal women who use estrogen replacement supplements may be more likely to develop kidney stones, according to a study published in the journal Archives of Internal Medicine.

In an effort to determine if hormone therapies increased a woman’s risk of this health problem, researchers examined the results of two studies. During the first trial, postmenopausal women who had a hysterectomy were asked to take an estrogen supplement, while a placebo was given to a control group. The same pills were used during the second study, but participants were postmenopausal women who hadn’t undergone a hysterectomy.

The researchers discovered that 335 participants who took the estrogen replacement supplement suffered from kidney stones, while 284 of those who were in the control groups developed the same complication.

The authors concluded that these findings “indicate that estrogen therapy increases the risk of [kidney stones] in healthy postmenopausal women.” They added that “in view of the sizable prevalence of [kidney stones] in this segment of the population, these [results] need to be considered in the decision-making process regarding postmenopausal estrogen use.”

In 2006, an estimated 166,000 people in the United States were hospitalized for kidney stones, according to the National Kidney and Urologic Disease Information Clearinghouse.