MEDROXYPROGESTERONE INCREASES BASAL TEMPERATURE - A PLACEBO-CONTROLLED CROSSOVER TRIAL IN POSTMENOPAUSAL WOMEN

Objective: To assess whether temperature is increased by medroxyproges terone (MPA) and thus whether basal temperature records could be used to determine ovulation during cyclic MPA therapy. Design: A 2-month do uble-blind placebo-controlled crossover trial in which oral basal temp erature was measured daily. Setting: Normal human volunteers in an aca demic medical environment. Subjects: Eleven postmenopausal women not t aking gonadal hormones. Intervention: Medroxyprogesterone acetate (10 mg/d) or placebo, calendar days 16 to 25, with crossover. Main Outcome Measures: Comparison of mean temperature days 17 to 26 during MPA ver sus placebo; comparison of differences between temperatures days 7 to 16 and 17 to 26 in MPA versus placebo months; and analysis for a signi ficant monthly thermal shift. Results: The mean temperatures during MP A. treatment averaged 0.27 degrees C higher than during the placebo ph ase and showed a significant change from pretreatment to ''treatment'' phases during MPA but not during placebo cycles. Eight of the MPA and one of the placebo cycles showed a shift from lower to higher tempera tures days 16 to 25. Conclusion: Medroxyprogesterone acetate has a phy siological progesterone-like thermal effect. Therefore basal temperatu re data cannot reliably indicate ovulation during cyclic MPA administr ation.