Effect of the subdermal contraceptive etonogestrel implant (Implanon) on biochemical and hormonal parameters (three years follow-up).

Objective: To determine whether the use of the subdermal contraceptive implant releasing etonogestrel (Implanon) affects serum hormonal and biochemical indices.

Methods: Seventy women with a mean age of 28.5+/-3.4 years were enrolled into this prospective observational study. After placement of an Implanon rod, they were followed-up for three years. Baseline and end-of-study values of serum low-density lipoprotein (LDL), high-density lipoprotein (HDL), cholesterol, triglycerides, fasting glucose, blood urea nitrogen (BUN), creatinine, SGOT, SGPT, follicle stimulating hormone (FSH), luteinizing hormone (LH), oestradiol, free 3,5,3'-tri-iodothyronine (fT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), and prolactine (PRL) were compared using Student's t-test.

Results: There was no failure of contraception during the three year period. No statistically significant differences were observed between the initial and final levels of fasting blood glucose, BUN, SGOT, SGPT, LDL, HDL, E2, FSH, LH, fT3, fT4 and TSH (p>0.05), but the increase in PRL, cholesterol and triglycerides, and the decrease in creatinine levels at the end of three years were statistically significant (p<0.05) although the values were still within normal ranges.

Conclusion: Our findings confirm data from the literature according to which Implanon does not affect meaningfully reproductive hormonal parameters, thyroid function, hepatic and renal functions, and glucose metabolism. However, further studies are needed to elucidate lipid metabolism changes.