Effect of Implanon® on lumbar bone mineral density
B. Dilbaz, O. Ozdegirmenci, E. Caliskan, S. Dilbaz, H. Tevrizci, A. Haberal
Department of Obstetrics and Gynaecology, SSK Maternity and Women’s
Health Teaching Hospital, Ankara, Turkey
Objective: To examine the bone mineral density (BMD) changes in
Implanon® users.
Design and methods: Forty-one women who chose Implanon® as a long
term contraception method were recruited to the study. Ethics committee approval
was obtained. Informed consent was given to all women who fulfilled the
inclusion criteria. Inclusion criterias were: age between 18 and 41 years, not
on medication affecting bone metabolism, not have a history of chronic disease
affecting calcium metabolism, not smoking or smoking <5 cigarettes a day. The initial laboratory assessment included serum estradiol levels. Initial estradiol was taken on day 1–5 (day of insertion). Second estradiol was obtained 6 months after insertion if amenorrheic any day, if not on the third day of bleeding. The women whose test results were within the laboratory reference range underwent BMD measurement. Bone mineral density measurements were done in the anteroposterior position at lumbar spine (L1-L4). The dual energy x-ray absorptiometry technique was used for measurements. The reason for selection of lumbar vertebrae for comparison was that, trabecular bone is most sensitive to factors that alter bone mineralization and a high percentage of trabecular bone was found in lumbar vertebraes. The BMD measurements were performed at baseline and after 6 months. Changes in the t, z and total scores of the BMD were compared for statistical significance using paired samples t test.
Results: Mean age of the patients was 27.9+5.03 years. The mean
duration of time from their last pregnancy was 30 months. Three percent of the
patients had no education while 52% of the patients graduated from primary, 20%
from secondary and 25% from high school. Serum estradiol levels at 6 months were
not statistically different from baseline levels. Although t, z and total scores
of the BMD at all levels of lumbar spine tended to increase, only increase in t
(p=0.03) and total (p=0.04) scores of L3 vertebrae were statistically
significant.
Conclusion: This study suggests that Implanon® is associated with
slight increase in all BMD scores but only changes in L3 vertebrae were
statistically significant. Since this study is limited within 6 months of period,
changes in BMD values after longer usage may be more apparent.
