Will progesterone serum levels be low with a Kyleena (levonorgestrel-releasing intrauterine device (IUD))?

Effect of Kyleena IUD on Progesterone Serum Levels

Progesterone serum levels will likely appear normal in most women with a Kyleena IUD, as this levonorgestrel-releasing intrauterine device primarily works through local effects on the endometrium rather than by suppressing ovulation or systemic hormone levels.

Mechanism of Action of Levonorgestrel IUDs

Kyleena is a levonorgestrel-releasing intrauterine device (LNG-IUD) that works primarily through local mechanisms:

• The primary contraceptive effect is through local action on the endometrium, causing endometrial suppression and thickening of cervical mucus 1
• Unlike combined hormonal contraceptives, LNG-IUDs do not consistently suppress ovulation 2
• After long-term use of LNG-IUDs, studies show that over two-thirds of women continue to have ovulatory cycles with normal progesterone production 2

Impact on Hormone Levels

• LNG-IUDs release much lower levels of hormones systemically compared to other hormonal contraceptives 3
• Research shows that after 6 years of LNG-IUD use, 78.5% of women had ovulatory cycles with normal hormonal profiles including progesterone 2
• Only 14.3% of women showed anovulatory cycles after long-term LNG-IUD use 2

Specific Considerations for Kyleena

Kyleena contains 19.5mg of levonorgestrel 4, which is:

• Higher than Skyla/Jaydess (13.5mg)
• Lower than Mirena (52mg)

This means:

• Kyleena releases a lower daily dose of levonorgestrel than Mirena
• The systemic effects on hormone levels are likely to be minimal
• Most women will maintain normal ovulatory cycles with normal progesterone production

Clinical Implications

• When interpreting progesterone levels in women with Kyleena IUDs:

  • Expect normal progesterone fluctuations in most women
  • Some women (approximately 14-20%) may have anovulatory cycles with lower progesterone levels
  • Irregular bleeding patterns may occur despite normal progesterone levels due to local endometrial effects 1, 3

• If measuring progesterone levels for clinical purposes:

  • Results should generally be interpreted using standard reference ranges
  • Consider the timing of the measurement in relation to the menstrual cycle
  • Remember that bleeding patterns with LNG-IUDs may not correlate with ovulatory status

Potential Pitfalls

• Do not assume abnormal progesterone levels are due to the Kyleena IUD without ruling out other causes
• Avoid confusing the local endometrial effects (which may cause amenorrhea or irregular bleeding) with systemic hormonal suppression
• Remember that LNG-IUDs like Kyleena have significantly lower systemic hormone effects compared to combined hormonal contraceptives 1

In summary, Kyleena IUD users will typically have normal serum progesterone levels as the device primarily works through local effects rather than by suppressing ovulation or systemic hormone production.