A cross-sectional study of the forearm bone density of long-term
users of the levonorgestrel-releasing intrauterine system, Mirena®
C.R.T. Juliato, L. Bahamondes, M.M. Hidalgo, C. Hidalgo-Regina, X. Espejo-Arce, C.A.
Petta
Human Reproduction Unit, Department of Obstetrics and Gynaecology, School
of Medicine, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
Background There are concerns about the effect of hormonal contraceptives on
bone mineral density (BMD) but there is currently no information available on
the effect of the levonorgestrel-releasing intrauterine system (LNG-IUS, Mirena®) on BMD. The objective of this study was to compare the BMD of Mirenaâ
users with that of controls using the TCu380A intrauterine device (IUD).
Materials and methods A cross-sectional study paired 53 women, aged 25 to 51,
who had been using the LNG-IUS for 7 years, with 53 IUD users, according to age
(± 1 year) and body mass index (BMI; kg/m2) (± 1). BMD was evaluated at the
midshaft of the ulna and the distal radius of the nondominant forearm using
double X-ray absorptiometry.
Results Mean age of women was 34 years. BMI was
slightly over 25 in both groups. Estradiol was normal. Mean BMD was 0.469 ±
0.008 and 0.467 ± 0.009 and 0.409 ± 0.009 and 0.411 ± 0.009 at the midshaft
of the ulna and distal radius in Mirena and IUD users, respectively, without
significant differences.
Conclusions Women aged 25 to 51, using the LNG-IUS for
seven years, had a mean BMD similar to that of the control group of TCu380A IUD
users.
KEY WORDS Bone mineral density, levonorgestrel-releasing intrauterine
system, Mirena, contraception.