Low-Dose Estrogen Spares Bones, Enhances Hormone Replacement Therapy
By Ray Fleming
Giving lower doses of estrogen and progesterone during hormone replacement therapy (HRT), in combination with calcium and vitamin D, spares older women significant osteoporotic bone mass loss while limiting HRT's significant side effects, according to a new NIAMS-supported study.
The randomized, controlled clinical trial (Ann Int Med. 1999; 130:897-904), carried out by Dr. Robert R. Recker and his colleagues at the NIAMS-sponsored Specialized Center of Research on Osteoporosis at Creighton University, tested a continuous daily regimen of 0.3 milligrams of estrogen (and 2.5 milligrams of progesterone) in women over 65 with low bone mass. The test dosage was less than half the HRT estrogen dosage most commonly prescribed to prevent osteoporosis. Calcium and vitamin D were added to ensure adequate patient levels. Over the course of the 3.5-year study, patients showed a 3.5 percent increase in spinal bone mineral density and significant increases in total body and forearm bone density — effects similar or better than higher dose regimens. Perhaps even more importantly, the women's experience of HRT side effects — such as breast tenderness, pelvic discomfort, mood changes and bleeding — was mild and short lived.
"HRT has long been the bedrock of osteoporosis prevention, but for many women, its side effects have been intolerable," says Recker . "Our results could mean that many more postmenopausal women who could benefit from the therapy would be willing to be treated, and with a higher compliance rate."
Dr. Joan McGowan, director of NIAMS' Musculoskeletal Diseases Branch, sees great potential benefits in the study's results. "Since estrogen is the first line of defense against osteoporosis," she says, "it's critical to use the lowest effective dose that will preserve and even add bone. This study provides important proof that low-dose estrogen can be an effective preventive and therapeutic option in older women with adequate calcium and vitamin D intake."
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