Thyroid function during the first year of use of the injectable contraceptive depot medroxyprogesterone acetate

Abstract

Purpose: The aim of the study was to evaluate thyroid function profile as a possible factor influencing weight and body composition variation in new users of depot medroxyprogesterone acetate (DMPA). Materials and methods: A prospective, non-randomised, comparative study was conducted at the University of Campinas, Brazil. Women aged 18–40 years with a body mass index (BMI) less than 30 kg/m2, normal oral glucose tolerance test, no known diseases, and using no medication, who opted to use DMPA were paired by age (±1 year) and BMI (±1 kg/m2) with women initiating copper intrauterine device (IUD) use. The main outcome measures were thyroid function profile, weight, and body composition, as measured by dual-energy X-ray absorptiometry. We used repeated measures ANOVA to perform comparisons between times and groups. Results: We evaluated 28 DMPA users and 24 IUD users who completed the 12-month follow-up. We observed that FT4 levels were higher at 12 months (compared to baseline) in the DMPA group (p < .0001) and that FT4/FT3 ratio had increased in both groups. Additionally, at 12 months, total body mass had increased around 2 kg and lean mass increased in the DMPA group compared to the IUD group; there was also an increase in weight, BMI, total body mass, and fat mass when compared to baseline. Conclusions: No changes in thyroid function occurred that could explain the weight increase observed in DMPA users. Trial registration: ClinicalTrials.gov identifier: NCT01527526.