Researchers Study Diuretics and Fractures in Postmenopausal Women

|

Researchers at UTHSC are helping to lead a national study examining the connection between loop diuretic use and osteoporosis-related fractures in postmenopausal women.

Researchers at the University of Tennessee Health Science Center (UTHSC) are helping to lead a national study examining the connection between loop diuretic use and osteoporosis-related fractures in postmenopausal women. The study is part of the Women’s Health Initiative (WHI), a long-term national effort to explore ways to prevent heart disease, breast and colorectal cancer, and fractures in postmenopausal women.

In the Memphis area, 3,960 postmenopausal women are participating in the WHI research. They are among nearly 162,000 women recruited nationwide for the initiative. Memphis is one of 40 clinical sites of the WHI, which is funded by the National Heart, Lung, and Blood Institute, part of the National Institutes of Health. Participants were identified for the WHI in the 1990s and will be followed until 2010.

The study’s background information notes that osteoporosis and heart failure are concerns for many postmenopausal women. Half will experience fractures caused by osteoporosis, and by age 40, their overall risk for developing heart failure is one in five. Heart failure is often treated with diuretics, sometimes referred to as “water pills,” to remove excess water from the body, making it easier for the heart to pump blood. Physicians commonly prescribe “loop” diuretics, which are more rapid acting than other diuretics, to treat patients with hypertension and congestive heart failure, conditions that occur in many postmenopausal women.

While loop diuretics treat heart-related problems by eliminating excess water, they simultaneously promote elimination of calcium by the kidneys, which can increase bone loss and fracture. In some studies, excessive loss of calcium in urine, or a condition known as “hypercalciuria,” is associated with low bone mineral density, a risk factor for fractures.

Findings from the WHI study over an eight-year period indicate that short-term use of loop diuretics does not appear to be associated with changes in bone mineral density, falls or fractures in postmenopausal women. However, prolonged use — three or more years — may slightly increase fracture risks in this group. These findings were reported in the January 26 issue of Archives of Internal Medicine, a peer-reviewed journal produced by Journal of the American Medical Association.

Lead researchers of the study, Laura Carbone, MD, UTHSC professor of medicine, and Karen C. Johnson, MD, MPH, UTHSC professor of preventive medicine and principal investigator of the WHI study in Memphis, find this news encouraging for women who must take diuretics to treat heart-related problems. Still, they caution that women who are prescribed loop diuretics long term should discuss their bone health with their health care provider.

Falls and fractures of study participants ages 50 to 79 were recorded for an average of 7.7 years. At baseline and at year three of the study, bone mineral density was measured for 300 diuretic users and 9,124 non-users. Women who used loop diuretics at some point in their lives were not found to be at a significant risk for total fractures, hip fractures, clinical vertebral fractures and falls. But, women who had used loop diuretics for three years or longer had a slightly increased risk for fractures.

Dr. Johnson, the WHI principal investigator in Memphis, concludes, “No significant association was found between short-term use of loop diuretics and changes in bone mineral density, falls or fractures in postmenopausal women in the WHI. However, prolonged use (three or more years) is associated with a slightly higher fracture risk in postmenopausal women. Therefore, fracture prevention measures in women who receive loop diuretic therapy are recommended, and women are encouraged to discuss bone health with their primary care providers.”