Serum uric acid levels and hormone therapy type: a retrospective cohort study of postmenopausal women

Objective: Serum uric acid levels increase in postmenopausal women, but decrease when hormone therapy (HT) is administered. No study has, however, evaluated the effects of different types of HT on serum uric acid levels. We therefore examined whether estrogen therapy (ET), estrogen plus progestogen therapy (EPT), and tibolone use affected serum uric acid levels in this population. Methods: We performed a retrospective cohort study of postmenopausal women. From 2005 to 2015, postmenopausal women who had undergone blood uric acid-level testing at least twice were enrolled. Participants were grouped according to HT regimen: ET, EPT, or tibolone. The nonhormone therapy group did not receive HT. Differences in serum uric acid levels were examined in each group. Our analysis was adjusted to accommodate different follow-up intervals for individual participants. Multiple variables were adjusted using the Tukey-Kramer method. Age, body mass index, hypertension, diabetes mellitus, dyslipidemia, estimated glomerular filtration rate, alcohol consumption, smoking status, and comedications were also adjusted. Results: After adjusting for multiple variables, the serum uric acid level increased to 0.87 +/- 0.27 mg/dL (least squares mean +/- standard error) in the nonhormone therapy group, and serum uric levels in the EPT group were found to be significantly lower (-0.38 +/- 0.29 mg/dL, P<0.001). The serum uric acid levels in the ET and tibolone groups did not, however, differ significantly from the nonhormone therapy group level. Conclusions: We attribute our findings to the effects of progestogen, rather than estrogen.