Kyleena IUD Does Not Increase SHBG Levels
The Kyleena IUD (levonorgestrel 19.5 mg) does not help increase sex hormone-binding globulin (SHBG) levels. In fact, levonorgestrel-releasing IUDs typically have the opposite effect, causing a decrease in SHBG levels.
Mechanism of Action and Hormonal Effects
Levonorgestrel-releasing IUDs like Kyleena work primarily through local effects on the endometrium, with much less systemic hormonal impact than oral contraceptives. The key differences include:
- Local vs. Systemic Effects: Kyleena releases a small amount of levonorgestrel directly into the uterine cavity, with minimal systemic absorption
- SHBG Impact: Studies have shown that levonorgestrel-containing contraceptives generally decrease SHBG levels rather than increase them 1
- Ovarian Function: After long-term use of levonorgestrel IUDs, over two-thirds of women maintain ovulatory cycles, indicating limited impact on overall hormonal function 1
Comparison with Other Contraceptive Methods
Different hormonal contraceptives have varying effects on SHBG:
- Combined Oral Contraceptives: Estrogen-containing pills typically increase SHBG levels, with the magnitude depending on the specific progestin component 2, 3
- Progestin-Only Methods: Generally associated with decreased SHBG levels
- Levonorgestrel-Specific Effects: Levonorgestrel has been shown to decrease SHBG levels in both oral and implantable forms 4
In one study comparing oral contraceptives, combinations containing desogestrel induced a substantial increase (213%) in SHBG capacity after 3 months, while levonorgestrel combinations showed a smaller increase (80%) due to the counteracting androgenic effects of levonorgestrel 2.
Clinical Implications
For patients specifically looking to increase SHBG levels:
- Kyleena IUD is not recommended as it contains levonorgestrel, which tends to decrease rather than increase SHBG
- Better alternatives would include combined oral contraceptives containing less androgenic progestins like desogestrel, which have been shown to significantly increase SHBG levels 3
- Non-contraceptive benefits of Kyleena IUD include reduction in menstrual bleeding and improvement in dysmenorrhea 5, but these are unrelated to SHBG effects
Important Considerations
- The Kyleena IUD is highly effective for contraception (99% efficacy) 6
- Levonorgestrel IUDs are particularly beneficial for women with heavy menstrual bleeding or dysmenorrhea 7
- After long-term use of levonorgestrel IUDs, serum levels of levonorgestrel are maintained but at lower levels than with systemic hormonal contraceptives 1
If increasing SHBG levels is the primary goal, other contraceptive options containing estrogen components would be more appropriate than the Kyleena IUD.