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Last Updated: 2001-08-10 14:04:03 EDT (Reuters Health)
By Will Boggs, MD
WESTPORT, CT (Reuters Health) – Lower doses of estrogen and medroxyprogesterone acetate, as part of hormone replacement therapy (HRT) in postmenopausal women have similar therapeutic effects has that seen with standard-dose HRT, according to a report in the July issue of Fertility and Sterility.
HRT with estrogen, alone or in combination with medroxyprogesterone acetate, lowers LDL cholesterol, raises HDL cholesterol, prevents osteoporosis and reduces cardiovascular mortality, the authors explain. Side effects, however, limit its use.
To determine whether HRT at lower doses would result in similar benefits, Dr. Rogerio A. Lobo from Columbia-Presbyterian Medical Center in New York and colleagues studied the effects of low-dose estrogen (0.3 mg, 0.45 mg, and 0.625 mg) with or without medroxyprogesterone (1.5 mg and 2.5 mg) in 749 postmenopausal women with an intact uterus. The subjects were healthy women between the ages of 45 and 65 years old.
All hormone treatment combinations resulted in significant increases in HDL cholesterol (p < 0.001)], the authors report, and all treatments in which the daily estrogen dose exceeded 0.3 mg brought significant declines in total cholesterol (p < 0.05) and LDL cholesterol (p < 0.02).
Treatment was also associated with an increase in triglycerides, apo A-I, and VLDL cholesterol, as well as with decreases in apo B and Lp(a), the report indicates.
Plasminogen activity increased and protein S activity decreased for all active treatment groups, the researchers note, while fibrinogen and antithrombin III activity decreased for all but the lowest combined treatment group.
Carbohydrate metabolism was minimally affected by the treatments, the results indicate.
"This study indicates that lower doses of conjugated equine estrogen alone or combined with lower doses of medroxyprogesterone acetate induce favorable changes in lipoproteins and modest changes in carbohydrate metabolism and hemostatic factors," the authors conclude.
Lower doses should be used as standard HRT and "standard" doses should only be used as necessary for symptoms, Dr. Lobo told Reuters Health. "This is analogous to what happened with oral contraceptives many years ago. And the trend now is to go even lower."
"Although we anticipate that the metabolic benefit observed in this younger postmenopausal population would pertain to older women as well," the researchers suggest, "this supposition will require confirmation in future studies."
"I think the low-dose regimens are most appropriate for women who are older (perhaps over 60)," Dr. Lobo added. "However, the data from the companion studies suggested equal efficacy as with standard doses even in younger women. So I think it is worthwhile starting with a lower dose and monitoring closely for things like bone mass and symptoms."
Fertil Steril 2001;76:13-24.
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