Estrogen Therapy Linked to High Prevalence of Kidney Stones
Women who choose estrogen therapy for postmenopausal hormone replacement seem to be at higher risk for kidney stone. In a study, women were either given placebo or the hormone as part of the national Women's Health Initiative study.
Naim M. Maalouf, M.D., of the University of Texas Southwestern Medical Center, Dallas found women receiving estrogen therapy had a higher risk of kidney stone, regardless of age, ethnicity, and prior use of hormone therapy, thiazide diuretics, body mass index, or coffee intake. Dr Maalouf used data from two trials of the study.
The authors write, “Because the process of kidney stone formation is influenced by a variety of lifestyle and other health-related factors, the true impact of estrogen therapy on the risk of kidney stone formation is difficult to infer from observational studies." They note that 5 to 7 percent of women who are postmenopausal suffer from the condition.
Kidney Stone Risk a Consideration for Women Choosing Estrogen Therapy
The findings suggest women should consider the risk found in the study when deciding whether to take estrogen hormone replacement therapy.
The study examined 10,739 postmenopausal women who had hysterectomy ad received either an estrogen-only treatment or matching placebo. The second trial included 16,608 postmenopausal women who had not had surgery and received either a combination of estrogen/progestin treatment or placebo.
Between the two groups, there were 335 cases of kidney stones were reported in the women receiving hormones and 284 cases in the placebo group, leading to the conclusion that is was the estrogen therapy causing kidney stone, also known as nephrolithiasis.
Women with a history of the condition were 5 times more likely to develop kidney stones at the start of the study, but not linked to estrogen. Data was collected for 7.1 years in the estrogen group and 5.6 years for women using combined hormone replacement therapy.
The conclusion that hormones increase kidney stone risk is something the authors say should be further investigated, and needs ”to be considered in the decision-making process regarding postmenopausal estrogen use." The research doesn’t show why hormone replacement therapy leads to kidney stones – something that also needs further study.
Arch Intern Med. 2010;170:1678-1685