replacement increases kidney stone risk
who take hormone replacement after menopause are at increased risk of developing
kidney stones, new research shows.
doesn't mean that women should stop taking hormone therapy based on this
fact, but it does need to be taken into account when deciding to take the
hormones or not," Dr. Naim M. Maalouf of the University of Texas Southwestern
Medical Center in Dallas, one of the study's authors, told Reuters Health.
5 to 7 percent of postmenopausal women in the U.S. suffer from kidney stones,
Maalouf and his colleagues note in the Archives of Internal Medicine. Kidney
stones aren't just extremely painful when they are passed out of the bladder;
"people who have kidney stones over time tend to have more kidney damage,"
to date of the relationship between hormone therapy and kidney stones have
had mixed results. To investigate, Maalouf and his colleagues reviewed data
from the Women's Health Initiative, the largest-ever randomized controlled
trial of hormone therapy for postmenopausal women.
analysis included 10,700 postmenopausal women who had undergone hysterectomy
and were randomly assigned to take estrogen or placebo, and another 16,600
who hadn't had hysterectomies and were put on either estrogen and progestin
or placebo. Women in the first group were followed for nearly six years,
while the women in the second group were followed for seven years.
on estrogen or the estrogen-progestin combination were 21 percent more likely
to develop kidney stones during the follow-up period, the researchers found.
When the researchers limited their analysis to women who didn't quit taking
their medication during the study period, kidney stone risk was 39 percent
greater with the hormones.
a woman's baseline risk for developing kidney stones of 7 percent, the study's
results mean that a postmenopausal woman's risk rises when taking hormone
therapy to between 8.5 percent and 10 percent.
process by which kidney stones form is "complex," the researchers
note, and has both environmental and genetic roots; there are also several
points in this process that could be affected by estrogen, they add.
women are at greater risk of developing kidney stones than women from other
ethnicities, Maalouf noted, while obesity has also been associated with
an increased tendency to form kidney stones. Drinking plenty of fluids can
help prevent kidney stones, while eating too much salt or too much protein
can make them more likely to develop, he added.
link.reuters.com/jar87p Archives of Internal Medicine, October 11, 2010.