Hormonal replacement therapy does not affect self-estimated pain or experimental pain responses in post-menopausal women suffering from fibromyalgia: a double-blind, randomized, placebo-controlled trial.
OBJECTIVES
FM is a condition that preferentially affects women. Sex hormones, and in particular oestrogens, have been shown to affect pain processing and pain sensitivity, and oestrogen deficit has been considered a potentially promoting factor for FM. However, the effects of oestrogen treatment in patients suffering from FM have not been studied. Here, we examined the effect of transdermal oestrogen substitution treatment on experimental as well as self-estimated pain in women suffering from FM.


METHODS
Twenty-nine post-menopausal women were randomized to either 8 weeks of treatment with transdermal 17β-oestradiol (50 µg/day) or placebo according to a double-blind protocol. A self-estimation of pain, a set of quantitative sensory tests measuring thresholds to temperature, thermal pain, cold pain and pressure pain, and a cold pressor test were performed on three occasions: before treatment, after 8 weeks of treatment and 20 weeks after cessation of treatment.


RESULTS
Hormonal replacement treatment significantly increased serum oestradiol levels as expected (P < 0.01). However, no differences in self-estimated pain were seen between treatment and placebo groups, nor were there any differences between the two groups regarding the results of the quantitative sensory tests or the cold pressor test at any of the examined time points.


CONCLUSION
Eight weeks of transdermal oestradiol treatment does not influence perceived pain, pain thresholds or pain tolerance as compared with placebo treatment in post-menopausal women suffering from FM.


TRIAL REGISTRATION
ClinicalTrials.gov Registration; http://www.clinicaltrials.gov; NCT01087593.