From the Guidelines
FSH and LH hormone levels should be interpreted based on the most recent and highest quality evidence, which suggests that normal FSH levels in premenopausal women range from 4-13 mIU/mL during the follicular phase, and normal LH levels range from 1-18 mIU/mL during the follicular phase 1. To determine the normal levels of FSH and LH, it's essential to consider the phase of the menstrual cycle and the individual's overall health.
- FSH levels:
- Follicular phase: 4-13 mIU/mL
- Mid-cycle: 5-22 mIU/mL
- Luteal phase: 2-13 mIU/mL
- LH levels:
- Follicular phase: 1-18 mIU/mL
- Mid-cycle: 24-105 mIU/mL
- Luteal phase: 0.4-20 mIU/mL These hormone levels are crucial for reproduction, and abnormal levels may indicate various conditions, such as menopause, primary gonadal failure, or pituitary disorders 1. It's also important to note that FSH and LH levels can be affected by various factors, including stress, excessive exercise, and certain medications, and should be interpreted by a healthcare provider in the context of individual factors and other test results 1. In clinical practice, FSH and LH levels should be measured and interpreted based on the most recent and highest quality evidence to ensure accurate diagnosis and treatment of reproductive disorders 1.
From the Research
FSH and LH Hormone Levels
- FSH (Follicle-Stimulating Hormone) and LH (Luteinizing Hormone) are essential hormones in the reproductive system, with FSH playing a key role in follicle development and LH in ovulation 2.
- The levels of FSH and LH can be used to predict reproductive age in normal women, with higher FSH levels and FSH:LH ratios observed in older women 3.
- FSH levels can be measured using various assays, but it is essential to specify the standard and assay method used for comparison 2.
- Reduced FSH and LH action can have significant implications for medically assisted reproduction, particularly in women with impaired gonadotropin production or action 4.
- The combination of FSH and LH levels on day 1 of the menstrual cycle can be a good predictor of age differences in women 3.
FSH and LH in Polycystic Ovary Syndrome (PCOS)
- In women with PCOS, ovulation induction with FSH is a second-line treatment for those who do not ovulate or conceive on clomiphene citrate or letrozole 5, 6.
- The effectiveness and safety of gonadotropins, including recombinant FSH (rFSH) and human menopausal gonadotropin (HMG), have been compared in women with PCOS, with varying results 5, 6.
- The use of gonadotropins in women with PCOS may result in more live births and clinical pregnancies compared to continued clomiphene citrate, but the evidence is not conclusive 5, 6.
Measurement and Definition of FSH
- FSH was historically defined based on classical in vivo endocrine activity, but subsequent developments in biotechnology have led to the recognition that there is no single molecule that can be uniquely defined as FSH 2.
- The World Health Organization established the first standard for FSH preparations in 1959, and several highly purified standards are now available 2.
- The measurement of FSH levels requires specification of the standard and assay method used for comparison, due to discontinuity and heterogeneity of estimates of FSH activity 2.