Objective evidence that placebo and oral medroxyprogesterone acetate therapy diminish menopausal vasomotor flushes

The vasomotor flush (VMF) is the most common reason for menopausal women to seek hormonal therapy, but the evaluation of therapeutic regimens has been hampered by the observation that placebo therapy can decrease VMF and, until recently, by a lack of objective criteria of measurement of the VMF. Using the objective criteria of temperature elevations (TEs) and luteinizing hormone (LH) pulses, we evaluated the effect of placebo and medroxyprogesterone acetate (MPA) on VMF. MPA and possibly also placebo were found to reduce not only the subjectively noted VMF but also the frequency of TEs recorded. In addition, MPA, but not placebo, significantly reduced the frequency and amplitude of LH pulses. Possible mechanisms of action of MPA and placebo therapy are discussed.