Effect of Kyleena IUD on Testosterone Levels
The Kyleena (levonorgestrel) IUD is unlikely to significantly decrease testosterone levels in most women due to its localized hormone delivery system.
Mechanism of Action and Hormone Effects
- The Kyleena IUD is a levonorgestrel-releasing intrauterine system (LNG-IUS) containing 19.5mg of levonorgestrel, licensed for contraception for up to 5 years 1.
- Unlike oral contraceptives containing levonorgestrel, the LNG-IUD delivers hormones locally to the uterus with minimal systemic absorption 2.
- Levonorgestrel can potentially bind to sex hormone binding globulin (SHBG) and displace testosterone, which could theoretically affect free testosterone levels 3.
Evidence on Testosterone Effects
- Research on the LNG-IUS (including Kyleena) shows that it does not significantly alter SHBG concentrations, unlike oral levonorgestrel contraception which can slightly decrease SHBG 4.
- Studies examining the LNG-IUS found no significant change in serum total testosterone concentrations during use 4.
- In contrast, oral levonorgestrel contraceptives have been shown to decrease total and free testosterone concentrations by approximately 41% and 55% respectively 5.
Comparison with Other Contraceptive Methods
- Oral contraceptives containing levonorgestrel have more pronounced effects on hormone levels due to first-pass metabolism through the liver, which affects protein synthesis including SHBG 5, 3.
- The systemic hormone levels with LNG-IUS are substantially lower than with oral contraceptives, resulting in fewer systemic hormonal effects 2.
- The localized delivery of levonorgestrel with IUDs like Kyleena primarily affects the endometrium rather than causing significant systemic hormonal changes 2.
Clinical Implications
- The LNG-IUD is generally considered to have minimal impact on systemic hormone levels compared to oral contraceptives 2, 4.
- For women concerned about hormonal side effects, the copper IUD remains an option with no hormonal component, though it may increase menstrual bleeding and cramping 2.
- Women with specific medical conditions affected by hormones (such as certain liver diseases) should be evaluated individually before LNG-IUD placement 2.
Monitoring Considerations
- Routine monitoring of testosterone levels is not recommended or necessary for users of the Kyleena IUD 2.
- The primary monitoring for IUD users focuses on ensuring proper placement and checking for complications such as infection or expulsion 2.
The localized action of the Kyleena IUD makes significant systemic hormonal effects, including testosterone reduction, much less likely compared to oral hormonal contraceptives 4, 3.