From the Guidelines
Luteinizing hormone (LH) levels typically surge to approximately 25-40 mIU/mL during ovulation, which is about 4-5 times higher than baseline levels, with baseline LH levels usually ranging from 5-10 mIU/mL during the follicular phase, as indicated by the most recent study 1. The LH surge is a crucial hormonal change for fertility, triggering the release of a mature egg from the ovary. Some key points to consider when evaluating LH levels for ovulation include:
- The LH surge typically occurs 24-36 hours before ovulation and lasts for about 1-2 days.
- Home ovulation predictor kits detect this surge, showing a positive result when LH levels reach this threshold.
- For women trying to conceive, testing should begin a few days before expected ovulation, typically around day 11 of a 28-day cycle.
- Testing once daily is usually sufficient, though some women may benefit from testing twice daily to catch the surge.
- The LH surge is a reliable predictor of ovulation, with ovulation typically occurring within 24-48 hours after the surge begins, as supported by the study 1. It's essential to note that LH levels can vary from woman to woman and even from cycle to cycle, so it's crucial to consider individual factors when interpreting LH levels for ovulation, as discussed in the study 1.
From the Research
LH Level for Ovulation
- The LH peak is a key biochemical marker for predicting ovulation, with a two to four fold increase above baseline levels for a relatively short 24-30 hour preovulatory period 2.
- Ovulation is considered to occur 28-36 hours after the beginning of the LH rise or 8-20 hours after the LH peak 2.
- The ideal thresholds to predict ovulation ranged between 25 and 30 mIU/ml with a positive predictive value (PPV) of 50-60%, negative predictive value (NPV) of 98%, positive likelihood ratio (LR+) of 20-30, and negative likelihood ratio (LR-) of 0.5 3.
- Beginning LH testing earlier in the cycle (day 7) with a threshold of 25-30 mIU/ml may present the best predictive value for ovulation within 24 h 3.
- LH induces a marked reduction in oestrogen production some 12 hours prior to ovulation and at the same time induces a two to three fold increase in progesterone production above baseline levels 2.
Factors Affecting LH Levels
- Clomiphene citrate (CC) treatment increases LH pulse amplitude and enhances estrogen secretion, leading to ovulation in women with polycystic ovary syndrome (PCOS) 4.
- Letrozole, an aromatase inhibitor, can be used as an adjuvant to recombinant follicle-stimulating hormone (rFSH) in controlled ovarian hyperstimulation, with a lower peak serum E(2) level compared to CC + rFSH 5.
- Virgin coconut oil (VCO) may synergize with clomiphene to depress hyperandrogenism and oxidative inflammation in PCOS, with a potential role in enhancing LH levels and reversing endocrine dysregulation 6.